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• Lu, J., Dreyer, I., Dickinson, M.S., Panzer, S., Jaslan, D., Navarro-Retamal, C., Geiger, D., Terpitz, U., Becker, D., Stroud, R.M., Marten, I., und Hedrich, R. (2023) „Vicia faba SV channel VfTPC1 is a hyperexcitable variant of plant vacuole Two Pore Channels“, Elife, 12, verfügbar unter: https://doi.org/10.7554/eLife.86384.
  • [ Abstract ]
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  To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca(2+). In our search for species-dependent functional TPC1 channel variants with different luminal Ca(2+) sensitivity, we found in total three acidic residues present in Ca(2+) sensor sites 2 and 3 of the Ca(2+)-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca(2+). When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca(2+) sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca(2+) sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche.

  @article{RN216, abstract = {To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca(2+). In our search for species-dependent functional TPC1 channel variants with different luminal Ca(2+) sensitivity, we found in total three acidic residues present in Ca(2+) sensor sites 2 and 3 of the Ca(2+)-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca(2+). When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca(2+) sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca(2+) sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche.}, author = {Lu, J. and Dreyer, I. and Dickinson, M. S. and Panzer, S. and Jaslan, D. and Navarro-Retamal, C. and Geiger, D. and Terpitz, U. and Becker, D. and Stroud, R. M. and Marten, I. and Hedrich, R.}, journal = {Elife}, keywords = {myOwn}, note = {Lu, Jinping Dreyer, Ingo Dickinson, Miles Sasha Panzer, Sabine Jaslan, Dawid Navarro-Retamal, Carlos Geiger, Dietmar Terpitz, Ulrich Becker, Dirk Stroud, Robert M Marten, Irene Hedrich, Rainer eng Koselleck award HE 1640/42-1/Deutsche Forschungsgemeinschaft/ priority programs 'MAdLand - Molecular Adaptation to Land: Plant Evolution to Change' HE 1640/45-1/Deutsche Forschungsgemeinschaft/ priority programs 'MAdLand - Molecular Adaptation to Land: Plant Evolution to Change' BE1867/9-1/Deutsche Forschungsgemeinschaft/ doctoral fellowship/China Scholarship Council/ STIPET fellowship/Deutscher Akademischer Austauschdienst/ FONDEQUIP EQM160063/Comision Nacional de Investigacion Cientifica y Tecnologica/ ATE220043/Anilio-Anid/ 3170434/Fondo Nacional de Desarrollo Cientifico y Tecnologico/ 1220504/Fondo Nacional de Desarrollo Cientifico y Tecnologico/ England 2023/11/22 Elife. 2023 Nov 22;12:e86384. doi: 10.7554/eLife.86384.}, title = {Vicia faba SV channel VfTPC1 is a hyperexcitable variant of plant vacuole Two Pore Channels}, type = {Journal Article}, volume = 12, year = 2023 }

  %0 Journal Article %1 RN216 %A Lu, J. %A Dreyer, I. %A Dickinson, M. S. %A Panzer, S. %A Jaslan, D. %A Navarro-Retamal, C. %A Geiger, D. %A Terpitz, U. %A Becker, D. %A Stroud, R. M. %A Marten, I. %A Hedrich, R. %D 2023 %J Elife %R 10.7554/eLife.86384 %T Vicia faba SV channel VfTPC1 is a hyperexcitable variant of plant vacuole Two Pore Channels %U https://www.ncbi.nlm.nih.gov/pubmed/37991833 %V 12 %X To fire action-potential-like electrical signals, the vacuole membrane requires the two-pore channel TPC1, formerly called SV channel. The TPC1/SV channel functions as a depolarization-stimulated, non-selective cation channel that is inhibited by luminal Ca(2+). In our search for species-dependent functional TPC1 channel variants with different luminal Ca(2+) sensitivity, we found in total three acidic residues present in Ca(2+) sensor sites 2 and 3 of the Ca(2+)-sensitive AtTPC1 channel from Arabidopsis thaliana that were neutral in its Vicia faba ortholog and also in those of many other Fabaceae. When expressed in the Arabidopsis AtTPC1-loss-of-function background, wild-type VfTPC1 was hypersensitive to vacuole depolarization and only weakly sensitive to blocking luminal Ca(2+). When AtTPC1 was mutated for these VfTPC1-homologous polymorphic residues, two neutral substitutions in Ca(2+) sensor site 3 alone were already sufficient for the Arabidopsis At-VfTPC1 channel mutant to gain VfTPC1-like voltage and luminal Ca(2+) sensitivity that together rendered vacuoles hyperexcitable. Thus, natural TPC1 channel variants exist in plant families which may fine-tune vacuole excitability and adapt it to environmental settings of the particular ecological niche.
• Huang, S., Maierhofer, T., Hashimoto, K., Xu, X., Karimi, S.M., Müller, H., Geringer, M.A., Wang, Y., Kudla, J., De Smet, I., Hedrich, R., Geiger, D., und Roelfsema, M.R.G. (2023) „The CIPK23 protein kinase represses SLAC1-type anion channels in Arabidopsis guard cells and stimulates stomatal opening“, New Phytol, 238(1), 270–282, verfügbar unter: https://doi.org/10.1111/nph.18708.
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  Guard cells control the opening of stomatal pores in the leaf surface, with the use of a network of protein kinases and phosphatases. Loss of function of the CBL-interacting protein kinase 23 (CIPK23) was previously shown to decrease the stomatal conductance, but the molecular mechanisms underlying this response still need to be clarified. CIPK23 was specifically expressed in Arabidopsis guard cells, using an estrogen-inducible system. Stomatal movements were linked to changes in ion channel activity, determined with double-barreled intracellular electrodes in guard cells and with the two-electrode voltage clamp technique in Xenopus oocytes. Expression of the phosphomimetic variant CIPK23

  @article{RN204, abstract = {Guard cells control the opening of stomatal pores in the leaf surface, with the use of a network of protein kinases and phosphatases. Loss of function of the CBL-interacting protein kinase 23 (CIPK23) was previously shown to decrease the stomatal conductance, but the molecular mechanisms underlying this response still need to be clarified. CIPK23 was specifically expressed in Arabidopsis guard cells, using an estrogen-inducible system. Stomatal movements were linked to changes in ion channel activity, determined with double-barreled intracellular electrodes in guard cells and with the two-electrode voltage clamp technique in Xenopus oocytes. Expression of the phosphomimetic variant CIPK23}, author = {Huang, S. and Maierhofer, T. and Hashimoto, K. and Xu, X. and Karimi, S. M. and Müller, H. and Geringer, M. A. and Wang, Y. and Kudla, J. and De Smet, I. and Hedrich, R. and Geiger, D. and Roelfsema, M. R. G.}, journal = {New Phytol}, keywords = {myOwn}, note = {Huang, Shouguang Maierhofer, Tobias Hashimoto, Kenji Xu, Xiangyu Karimi, Sohail M Müller, Heike Geringer, Michael A Wang, Yi Kudla, Jörg De Smet, Ive Hedrich, Rainer Geiger, Dietmar Roelfsema, M Rob G 2023/1/5}, number = 1, pages = {270-282}, title = {The CIPK23 protein kinase represses SLAC1-type anion channels in Arabidopsis guard cells and stimulates stomatal opening}, type = {Journal Article}, volume = 238, year = 2023 }

  %0 Journal Article %1 RN204 %A Huang, S. %A Maierhofer, T. %A Hashimoto, K. %A Xu, X. %A Karimi, S. M. %A Müller, H. %A Geringer, M. A. %A Wang, Y. %A Kudla, J. %A De Smet, I. %A Hedrich, R. %A Geiger, D. %A Roelfsema, M. R. G. %D 2023 %J New Phytol %N 1 %P 270-282 %R 10.1111/nph.18708 %T The CIPK23 protein kinase represses SLAC1-type anion channels in Arabidopsis guard cells and stimulates stomatal opening %U https://www.ncbi.nlm.nih.gov/pubmed/36597715 %V 238 %X Guard cells control the opening of stomatal pores in the leaf surface, with the use of a network of protein kinases and phosphatases. Loss of function of the CBL-interacting protein kinase 23 (CIPK23) was previously shown to decrease the stomatal conductance, but the molecular mechanisms underlying this response still need to be clarified. CIPK23 was specifically expressed in Arabidopsis guard cells, using an estrogen-inducible system. Stomatal movements were linked to changes in ion channel activity, determined with double-barreled intracellular electrodes in guard cells and with the two-electrode voltage clamp technique in Xenopus oocytes. Expression of the phosphomimetic variant CIPK23

• Değirmenci, L., Rogé Ferreira, F.L., Vukosavljevic, A., Heindl, C., Keller, A., Geiger, D., und Scheiner, R. (2022) „Sugar perception in honeybees“, Front Physiol, 13, 1089669, verfügbar unter: https://doi.org/10.3389/fphys.2022.1089669.
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  Honeybees (

  @article{RN214, abstract = {Honeybees (}, author = {Değirmenci, L. and Rogé Ferreira, F. L. and Vukosavljevic, A. and Heindl, C. and Keller, A. and Geiger, D. and Scheiner, R.}, journal = {Front Physiol}, keywords = {myOwn}, note = {Değirmenci, Laura Rogé Ferreira, Fabio Luiz Vukosavljevic, Adrian Heindl, Cornelia Keller, Alexander Geiger, Dietmar Scheiner, Ricarda 2023/1/31}, pages = 1089669, title = {Sugar perception in honeybees}, type = {Journal Article}, volume = 13, year = 2022 }

  %0 Journal Article %1 RN214 %A Değirmenci, L. %A Rogé Ferreira, F. L. %A Vukosavljevic, A. %A Heindl, C. %A Keller, A. %A Geiger, D. %A Scheiner, R. %D 2022 %J Front Physiol %P 1089669 %R 10.3389/fphys.2022.1089669 %T Sugar perception in honeybees %U https://www.ncbi.nlm.nih.gov/pubmed/36714315 %V 13 %X Honeybees (
• Yang, B., Wang, J., Yu, M., Zhang, M., Zhong, Y., Wang, T., Liu, P., Song, W., Zhao, H., Fastner, A., Suter, M., Rentsch, D., Ludewig, U., Jin, W., Geiger, D., Hedrich, R., Braun, D.M., Koch, K.E., McCarty, D.R., Wu, W.H., Li, X., Wang, Y., und Lai, J. (2022) „The sugar transporter ZmSUGCAR1 of the nitrate transporter 1/peptide transporter family is critical for maize grain filling“, Plant Cell, 34(11), 4232–4254, verfügbar unter: https://doi.org/10.1093/plcell/koac256.
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  Maternal-to-filial nutrition transfer is central to grain development and yield. nitrate transporter 1/peptide transporter (NRT1-PTR)-type transporters typically transport nitrate, peptides, and ions. Here, we report the identification of a maize (Zea mays) NRT1-PTR-type transporter that transports sucrose and glucose. The activity of this sugar transporter, named Sucrose and Glucose Carrier 1 (SUGCAR1), was systematically verified by tracer-labeled sugar uptake and serial electrophysiological studies including two-electrode voltage-clamp, non-invasive microelectrode ion flux estimation assays in Xenopus laevis oocytes and patch clamping in HEK293T cells. ZmSUGCAR1 is specifically expressed in the basal endosperm transfer layer and loss-of-function mutation of ZmSUGCAR1 caused significantly decreased sucrose and glucose contents and subsequent shrinkage of maize kernels. Notably, the ZmSUGCAR1 orthologs SbSUGCAR1 (from Sorghum bicolor) and TaSUGCAR1 (from Triticum aestivum) displayed similar sugar transport activities in oocytes, supporting the functional conservation of SUGCAR1 in closely related cereal species. Thus, the discovery of ZmSUGCAR1 uncovers a type of sugar transporter essential for grain development and opens potential avenues for genetic improvement of seed-filling and yield in maize and other grain crops.

  @article{RN205, abstract = {Maternal-to-filial nutrition transfer is central to grain development and yield. nitrate transporter 1/peptide transporter (NRT1-PTR)-type transporters typically transport nitrate, peptides, and ions. Here, we report the identification of a maize (Zea mays) NRT1-PTR-type transporter that transports sucrose and glucose. The activity of this sugar transporter, named Sucrose and Glucose Carrier 1 (SUGCAR1), was systematically verified by tracer-labeled sugar uptake and serial electrophysiological studies including two-electrode voltage-clamp, non-invasive microelectrode ion flux estimation assays in Xenopus laevis oocytes and patch clamping in HEK293T cells. ZmSUGCAR1 is specifically expressed in the basal endosperm transfer layer and loss-of-function mutation of ZmSUGCAR1 caused significantly decreased sucrose and glucose contents and subsequent shrinkage of maize kernels. Notably, the ZmSUGCAR1 orthologs SbSUGCAR1 (from Sorghum bicolor) and TaSUGCAR1 (from Triticum aestivum) displayed similar sugar transport activities in oocytes, supporting the functional conservation of SUGCAR1 in closely related cereal species. Thus, the discovery of ZmSUGCAR1 uncovers a type of sugar transporter essential for grain development and opens potential avenues for genetic improvement of seed-filling and yield in maize and other grain crops.}, author = {Yang, B. and Wang, J. and Yu, M. and Zhang, M. and Zhong, Y. and Wang, T. and Liu, P. and Song, W. and Zhao, H. and Fastner, A. and Suter, M. and Rentsch, D. and Ludewig, U. and Jin, W. and Geiger, D. and Hedrich, R. and Braun, D. M. and Koch, K. E. and McCarty, D. R. and Wu, W. H. and Li, X. and Wang, Y. and Lai, J.}, journal = {Plant Cell}, keywords = {myOwn}, note = {Yang, Bo Wang, Jing Yu, Miao Zhang, Meiling Zhong, Yanting Wang, Tianyi Liu, Peng Song, Weibin Zhao, Haiming Fastner, Astrid Suter, Marianne Rentsch, Doris Ludewig, Uwe Jin, Weiwei Geiger, Dietmar Hedrich, Rainer Braun, David M Koch, Karen E McCarty, Donald R Wu, Wei-Hua Li, Xuexian Wang, Yi Lai, Jinsheng 2022/9/2}, number = 11, pages = {4232-4254}, title = {The sugar transporter ZmSUGCAR1 of the nitrate transporter 1/peptide transporter family is critical for maize grain filling}, type = {Journal Article}, volume = 34, year = 2022 }

  %0 Journal Article %1 RN205 %A Yang, B. %A Wang, J. %A Yu, M. %A Zhang, M. %A Zhong, Y. %A Wang, T. %A Liu, P. %A Song, W. %A Zhao, H. %A Fastner, A. %A Suter, M. %A Rentsch, D. %A Ludewig, U. %A Jin, W. %A Geiger, D. %A Hedrich, R. %A Braun, D. M. %A Koch, K. E. %A McCarty, D. R. %A Wu, W. H. %A Li, X. %A Wang, Y. %A Lai, J. %D 2022 %J Plant Cell %N 11 %P 4232-4254 %R 10.1093/plcell/koac256 %T The sugar transporter ZmSUGCAR1 of the nitrate transporter 1/peptide transporter family is critical for maize grain filling %U https://www.ncbi.nlm.nih.gov/pubmed/36047828 %V 34 %X Maternal-to-filial nutrition transfer is central to grain development and yield. nitrate transporter 1/peptide transporter (NRT1-PTR)-type transporters typically transport nitrate, peptides, and ions. Here, we report the identification of a maize (Zea mays) NRT1-PTR-type transporter that transports sucrose and glucose. The activity of this sugar transporter, named Sucrose and Glucose Carrier 1 (SUGCAR1), was systematically verified by tracer-labeled sugar uptake and serial electrophysiological studies including two-electrode voltage-clamp, non-invasive microelectrode ion flux estimation assays in Xenopus laevis oocytes and patch clamping in HEK293T cells. ZmSUGCAR1 is specifically expressed in the basal endosperm transfer layer and loss-of-function mutation of ZmSUGCAR1 caused significantly decreased sucrose and glucose contents and subsequent shrinkage of maize kernels. Notably, the ZmSUGCAR1 orthologs SbSUGCAR1 (from Sorghum bicolor) and TaSUGCAR1 (from Triticum aestivum) displayed similar sugar transport activities in oocytes, supporting the functional conservation of SUGCAR1 in closely related cereal species. Thus, the discovery of ZmSUGCAR1 uncovers a type of sugar transporter essential for grain development and opens potential avenues for genetic improvement of seed-filling and yield in maize and other grain crops.

• Schartl, M., Kneitz, S., Ormanns, J., Schmidt, C., Anderson, J.L., Amores, A., Catchen, J., Wilson, C., Geiger, D., Du, K., Garcia-Olazábal, M., Sudaram, S., Winkler, C., Hedrich, R., Warren, W.C., Walter, R., Meyer, A., und Postlethwait, J.H. (2021) „The Developmental and Genetic Architecture of the Sexually Selected Male Ornament of Swordtails“, Curr Biol, 31(5), 911–922.e4, verfügbar unter: https://doi.org/10.1016/j.cub.2020.11.028.
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  Sexual selection results in sex-specific characters like the conspicuously pigmented extension of the ventral tip of the caudal fin-the "sword"-in males of several species of Xiphophorus fishes. To uncover the genetic architecture underlying sword formation and to identify genes that are associated with its development, we characterized the sword transcriptional profile and combined it with genetic mapping approaches. Results showed that the male ornament of swordtails develops from a sexually non-dimorphic prepattern of transcription factors in the caudal fin. Among genes that constitute the exclusive sword transcriptome and are located in the genomic region associated with this trait we identify the potassium channel, Kcnh8, as a sword development gene. In addition to its neural function kcnh8 performs a known role in fin growth. These findings indicate that during evolution of swordtails a brain gene has been co-opted for an additional novel function in establishing a male ornament.

  @article{RN208, abstract = {Sexual selection results in sex-specific characters like the conspicuously pigmented extension of the ventral tip of the caudal fin-the "sword"-in males of several species of Xiphophorus fishes. To uncover the genetic architecture underlying sword formation and to identify genes that are associated with its development, we characterized the sword transcriptional profile and combined it with genetic mapping approaches. Results showed that the male ornament of swordtails develops from a sexually non-dimorphic prepattern of transcription factors in the caudal fin. Among genes that constitute the exclusive sword transcriptome and are located in the genomic region associated with this trait we identify the potassium channel, Kcnh8, as a sword development gene. In addition to its neural function kcnh8 performs a known role in fin growth. These findings indicate that during evolution of swordtails a brain gene has been co-opted for an additional novel function in establishing a male ornament.}, author = {Schartl, M. and Kneitz, S. and Ormanns, J. and Schmidt, C. and Anderson, J. L. and Amores, A. and Catchen, J. and Wilson, C. and Geiger, D. and Du, K. and Garcia-Olazábal, M. and Sudaram, S. and Winkler, C. and Hedrich, R. and Warren, W. C. and Walter, R. and Meyer, A. and Postlethwait, J. H.}, journal = {Curr Biol}, keywords = {myOwn}, note = {Schartl, Manfred Kneitz, Susanne Ormanns, Jenny Schmidt, Cornelia Anderson, Jennifer L Amores, Angel Catchen, Julian Wilson, Catherine Geiger, Dietmar Du, Kang Garcia-Olazábal, Mateo Sudaram, Sudha Winkler, Christoph Hedrich, Rainer Warren, Wesley C Walter, Ronald Meyer, Axel Postlethwait, John H 2020/12/5}, number = 5, pages = {911-922.e4}, title = {The Developmental and Genetic Architecture of the Sexually Selected Male Ornament of Swordtails}, type = {Journal Article}, volume = 31, year = 2021 }

  %0 Journal Article %1 RN208 %A Schartl, M. %A Kneitz, S. %A Ormanns, J. %A Schmidt, C. %A Anderson, J. L. %A Amores, A. %A Catchen, J. %A Wilson, C. %A Geiger, D. %A Du, K. %A Garcia-Olazábal, M. %A Sudaram, S. %A Winkler, C. %A Hedrich, R. %A Warren, W. C. %A Walter, R. %A Meyer, A. %A Postlethwait, J. H. %D 2021 %J Curr Biol %N 5 %P 911-922.e4 %R 10.1016/j.cub.2020.11.028 %T The Developmental and Genetic Architecture of the Sexually Selected Male Ornament of Swordtails %U https://www.ncbi.nlm.nih.gov/pubmed/33275891 %V 31 %X Sexual selection results in sex-specific characters like the conspicuously pigmented extension of the ventral tip of the caudal fin-the "sword"-in males of several species of Xiphophorus fishes. To uncover the genetic architecture underlying sword formation and to identify genes that are associated with its development, we characterized the sword transcriptional profile and combined it with genetic mapping approaches. Results showed that the male ornament of swordtails develops from a sexually non-dimorphic prepattern of transcription factors in the caudal fin. Among genes that constitute the exclusive sword transcriptome and are located in the genomic region associated with this trait we identify the potassium channel, Kcnh8, as a sword development gene. In addition to its neural function kcnh8 performs a known role in fin growth. These findings indicate that during evolution of swordtails a brain gene has been co-opted for an additional novel function in establishing a male ornament.
• Lehmann, J., Jørgensen, M.E., Fratz, S., Müller, H.M., Kusch, J., Scherzer, S., Navarro-Retamal, C., Mayer, D., Böhm, J., Konrad, K.R., Terpitz, U., Dreyer, I., Mueller, T.D., Sauer, M., Hedrich, R., Geiger, D., und Maierhofer, T. (2021) „Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis“, Curr Biol, 31(16), 3575–3585.e9, verfügbar unter: https://doi.org/10.1016/j.cub.2021.06.018.
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  Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.

  @article{RN206, abstract = {Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.}, author = {Lehmann, J. and Jørgensen, M. E. and Fratz, S. and Müller, H. M. and Kusch, J. and Scherzer, S. and Navarro-Retamal, C. and Mayer, D. and Böhm, J. and Konrad, K. R. and Terpitz, U. and Dreyer, I. and Mueller, T. D. and Sauer, M. and Hedrich, R. and Geiger, D. and Maierhofer, T.}, journal = {Curr Biol}, keywords = {myOwn}, note = {Lehmann, Julian Jørgensen, Morten E Fratz, Stefanie Müller, Heike M Kusch, Jana Scherzer, Sönke Navarro-Retamal, Carlos Mayer, Dominik Böhm, Jennifer Konrad, Kai R Terpitz, Ulrich Dreyer, Ingo Mueller, Thomas D Sauer, Markus Hedrich, Rainer Geiger, Dietmar Maierhofer, Tobias 2021/7/8}, number = 16, pages = {3575-3585.e9}, title = {Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis}, type = {Journal Article}, volume = 31, year = 2021 }

  %0 Journal Article %1 RN206 %A Lehmann, J. %A Jørgensen, M. E. %A Fratz, S. %A Müller, H. M. %A Kusch, J. %A Scherzer, S. %A Navarro-Retamal, C. %A Mayer, D. %A Böhm, J. %A Konrad, K. R. %A Terpitz, U. %A Dreyer, I. %A Mueller, T. D. %A Sauer, M. %A Hedrich, R. %A Geiger, D. %A Maierhofer, T. %D 2021 %J Curr Biol %N 16 %P 3575-3585.e9 %R 10.1016/j.cub.2021.06.018 %T Acidosis-induced activation of anion channel SLAH3 in the flooding-related stress response of Arabidopsis %U https://www.ncbi.nlm.nih.gov/pubmed/34233161 %V 31 %X Plants, as sessile organisms, gained the ability to sense and respond to biotic and abiotic stressors to survive severe changes in their environments. The change in our climate comes with extreme dry periods but also episodes of flooding. The latter stress condition causes anaerobiosis-triggered cytosolic acidosis and impairs plant function. The molecular mechanism that enables plant cells to sense acidity and convey this signal via membrane depolarization was previously unknown. Here, we show that acidosis-induced anion efflux from Arabidopsis (Arabidopsis thaliana) roots is dependent on the S-type anion channel AtSLAH3. Heterologous expression of SLAH3 in Xenopus oocytes revealed that the anion channel is directly activated by a small, physiological drop in cytosolic pH. Acidosis-triggered activation of SLAH3 is mediated by protonation of histidine 330 and 454. Super-resolution microscopy analysis showed that the increase in cellular proton concentration switches SLAH3 from an electrically silent channel dimer into its active monomeric form. Our results show that, upon acidification, protons directly switch SLAH3 to its open configuration, bypassing kinase-dependent activation. Moreover, under flooding conditions, the stress response of Arabidopsis wild-type (WT) plants was significantly higher compared to SLAH3 loss-of-function mutants. Our genetic evidence of SLAH3 pH sensor function may guide the development of crop varieties with improved stress tolerance.
• Garcia-Maquilon, I., Coego, A., Lozano-Juste, J., Messerer, M., de Ollas, C., Julian, J., Ruiz-Partida, R., Pizzio, G., Belda-Palazón, B., Gomez-Cadenas, A., Mayer, K.F.X., Geiger, D., Alquraishi, S.A., Alrefaei, A.F., Ache, P., Hedrich, R., und Rodriguez, P.L. (2021) „PYL8 ABA receptors of Phoenix dactylifera play a crucial role in response to abiotic stress and are stabilized by ABA“, J Exp Bot, 72(2), 757–774, verfügbar unter: https://doi.org/10.1093/jxb/eraa476.
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  The identification of those prevalent abscisic acid (ABA) receptors and molecular mechanisms that trigger drought adaptation in crops well adapted to harsh conditions such as date palm (Phoenix dactylifera, Pd) sheds light on plant-environment interactions. We reveal that PdPYL8-like receptors are predominantly expressed under abiotic stress, with Pd27 being the most expressed receptor in date palm. Therefore, subfamily I PdPYL8-like receptors have been selected for ABA signaling during abiotic stress response in this crop. Biochemical characterization of PdPYL8-like and PdPYL1-like receptors revealed receptor- and ABA-dependent inhibition of PP2Cs, which triggers activation of the pRD29B-LUC reporter in response to ABA. PdPYLs efficiently abolish PP2C-mediated repression of ABA signaling, but loss of the Trp lock in the seed-specific AHG1-like phosphatase PdPP2C79 markedly impairs its inhibition by ABA receptors. Characterization of Arabidopsis transgenic plants that express PdPYLs shows enhanced ABA signaling in seed, root, and guard cells. Specifically, Pd27-overexpressing plants showed lower ABA content and were more efficient than the wild type in lowering transpiration at negative soil water potential, leading to enhanced drought tolerance. Finally, PdPYL8-like receptors accumulate after ABA treatment, which suggests that ABA-induced stabilization of these receptors operates in date palm for efficient boosting of ABA signaling in response to abiotic stress.

  @article{RN207, abstract = {The identification of those prevalent abscisic acid (ABA) receptors and molecular mechanisms that trigger drought adaptation in crops well adapted to harsh conditions such as date palm (Phoenix dactylifera, Pd) sheds light on plant-environment interactions. We reveal that PdPYL8-like receptors are predominantly expressed under abiotic stress, with Pd27 being the most expressed receptor in date palm. Therefore, subfamily I PdPYL8-like receptors have been selected for ABA signaling during abiotic stress response in this crop. Biochemical characterization of PdPYL8-like and PdPYL1-like receptors revealed receptor- and ABA-dependent inhibition of PP2Cs, which triggers activation of the pRD29B-LUC reporter in response to ABA. PdPYLs efficiently abolish PP2C-mediated repression of ABA signaling, but loss of the Trp lock in the seed-specific AHG1-like phosphatase PdPP2C79 markedly impairs its inhibition by ABA receptors. Characterization of Arabidopsis transgenic plants that express PdPYLs shows enhanced ABA signaling in seed, root, and guard cells. Specifically, Pd27-overexpressing plants showed lower ABA content and were more efficient than the wild type in lowering transpiration at negative soil water potential, leading to enhanced drought tolerance. Finally, PdPYL8-like receptors accumulate after ABA treatment, which suggests that ABA-induced stabilization of these receptors operates in date palm for efficient boosting of ABA signaling in response to abiotic stress.}, author = {Garcia-Maquilon, I. and Coego, A. and Lozano-Juste, J. and Messerer, M. and de Ollas, C. and Julian, J. and Ruiz-Partida, R. and Pizzio, G. and Belda-Palazón, B. and Gomez-Cadenas, A. and Mayer, K. F. X. and Geiger, D. and Alquraishi, S. A. and Alrefaei, A. F. and Ache, P. and Hedrich, R. and Rodriguez, P. L.}, journal = {J Exp Bot}, keywords = {myOwn}, note = {Garcia-Maquilon, Irene Coego, Alberto Lozano-Juste, Jorge Messerer, Maxim de Ollas, Carlos Julian, Jose Ruiz-Partida, Rafael Pizzio, Gaston Belda-Palazón, Borja Gomez-Cadenas, Aurelio Mayer, Klaus F X Geiger, Dietmar Alquraishi, Saleh A Alrefaei, Abdulwahed F Ache, Peter Hedrich, Rainer Rodriguez, Pedro L 2021/2/3}, number = 2, pages = {757-774}, title = {PYL8 ABA receptors of Phoenix dactylifera play a crucial role in response to abiotic stress and are stabilized by ABA}, type = {Journal Article}, volume = 72, year = 2021 }

  %0 Journal Article %1 RN207 %A Garcia-Maquilon, I. %A Coego, A. %A Lozano-Juste, J. %A Messerer, M. %A de Ollas, C. %A Julian, J. %A Ruiz-Partida, R. %A Pizzio, G. %A Belda-Palazón, B. %A Gomez-Cadenas, A. %A Mayer, K. F. X. %A Geiger, D. %A Alquraishi, S. A. %A Alrefaei, A. F. %A Ache, P. %A Hedrich, R. %A Rodriguez, P. L. %D 2021 %J J Exp Bot %N 2 %P 757-774 %R 10.1093/jxb/eraa476 %T PYL8 ABA receptors of Phoenix dactylifera play a crucial role in response to abiotic stress and are stabilized by ABA %U https://www.ncbi.nlm.nih.gov/pubmed/33529339 %V 72 %X The identification of those prevalent abscisic acid (ABA) receptors and molecular mechanisms that trigger drought adaptation in crops well adapted to harsh conditions such as date palm (Phoenix dactylifera, Pd) sheds light on plant-environment interactions. We reveal that PdPYL8-like receptors are predominantly expressed under abiotic stress, with Pd27 being the most expressed receptor in date palm. Therefore, subfamily I PdPYL8-like receptors have been selected for ABA signaling during abiotic stress response in this crop. Biochemical characterization of PdPYL8-like and PdPYL1-like receptors revealed receptor- and ABA-dependent inhibition of PP2Cs, which triggers activation of the pRD29B-LUC reporter in response to ABA. PdPYLs efficiently abolish PP2C-mediated repression of ABA signaling, but loss of the Trp lock in the seed-specific AHG1-like phosphatase PdPP2C79 markedly impairs its inhibition by ABA receptors. Characterization of Arabidopsis transgenic plants that express PdPYLs shows enhanced ABA signaling in seed, root, and guard cells. Specifically, Pd27-overexpressing plants showed lower ABA content and were more efficient than the wild type in lowering transpiration at negative soil water potential, leading to enhanced drought tolerance. Finally, PdPYL8-like receptors accumulate after ABA treatment, which suggests that ABA-induced stabilization of these receptors operates in date palm for efficient boosting of ABA signaling in response to abiotic stress.

• Değirmenci, L., Geiger, D., Rogé Ferreira, F.L., Keller, A., Krischke, B., Beye, M., Steffan-Dewenter, I., und Scheiner, R. (2020) „CRISPR/Cas 9-Mediated Mutations as a New Tool for Studying Taste in Honeybees“, Chem Senses, 45(8), 655–666, verfügbar unter: https://doi.org/10.1093/chemse/bjaa063.
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  Honeybees rely on nectar as their main source of carbohydrates. Sucrose, glucose, and fructose are the main components of plant nectars. Intriguingly, honeybees express only 3 putative sugar receptors (AmGr1, AmGr2, and AmGr3), which is in stark contrast to many other insects and vertebrates. The sugar receptors are only partially characterized. AmGr1 detects different sugars including sucrose and glucose. AmGr2 is assumed to act as a co-receptor only, while AmGr3 is assumedly a fructose receptor. We show that honeybee gustatory receptor AmGr3 is highly specialized for fructose perception when expressed in Xenopus oocytes. When we introduced nonsense mutations to the respective AmGr3 gene using CRISPR/Cas9 in eggs of female workers, the resulting mutants displayed almost a complete loss of responsiveness to fructose. In contrast, responses to sucrose were normal. Nonsense mutations introduced by CRISPR/Cas9 in honeybees can thus induce a measurable behavioral change and serve to characterize the function of taste receptors in vivo. CRISPR/Cas9 is an excellent novel tool for characterizing honeybee taste receptors in vivo. Biophysical receptor characterization in Xenopus oocytes and nonsense mutation of AmGr3 in honeybees unequivocally demonstrate that this receptor is highly specific for fructose.

  @article{RN215, abstract = {Honeybees rely on nectar as their main source of carbohydrates. Sucrose, glucose, and fructose are the main components of plant nectars. Intriguingly, honeybees express only 3 putative sugar receptors (AmGr1, AmGr2, and AmGr3), which is in stark contrast to many other insects and vertebrates. The sugar receptors are only partially characterized. AmGr1 detects different sugars including sucrose and glucose. AmGr2 is assumed to act as a co-receptor only, while AmGr3 is assumedly a fructose receptor. We show that honeybee gustatory receptor AmGr3 is highly specialized for fructose perception when expressed in Xenopus oocytes. When we introduced nonsense mutations to the respective AmGr3 gene using CRISPR/Cas9 in eggs of female workers, the resulting mutants displayed almost a complete loss of responsiveness to fructose. In contrast, responses to sucrose were normal. Nonsense mutations introduced by CRISPR/Cas9 in honeybees can thus induce a measurable behavioral change and serve to characterize the function of taste receptors in vivo. CRISPR/Cas9 is an excellent novel tool for characterizing honeybee taste receptors in vivo. Biophysical receptor characterization in Xenopus oocytes and nonsense mutation of AmGr3 in honeybees unequivocally demonstrate that this receptor is highly specific for fructose.}, author = {Değirmenci, L. and Geiger, D. and Rogé Ferreira, F. L. and Keller, A. and Krischke, B. and Beye, M. and Steffan-Dewenter, I. and Scheiner, R.}, journal = {Chem Senses}, keywords = {myOwn}, note = {Değirmenci, Laura Geiger, Dietmar Rogé Ferreira, Fábio Luiz Keller, Alexander Krischke, Beate Beye, Martin Steffan-Dewenter, Ingolf Scheiner, Ricarda 2020/9/25}, number = 8, pages = {655-666}, title = {CRISPR/Cas 9-Mediated Mutations as a New Tool for Studying Taste in Honeybees}, type = {Journal Article}, volume = 45, year = 2020 }

  %0 Journal Article %1 RN215 %A Değirmenci, L. %A Geiger, D. %A Rogé Ferreira, F. L. %A Keller, A. %A Krischke, B. %A Beye, M. %A Steffan-Dewenter, I. %A Scheiner, R. %D 2020 %J Chem Senses %N 8 %P 655-666 %R 10.1093/chemse/bjaa063 %T CRISPR/Cas 9-Mediated Mutations as a New Tool for Studying Taste in Honeybees %U https://www.ncbi.nlm.nih.gov/pubmed/32968780 %V 45 %X Honeybees rely on nectar as their main source of carbohydrates. Sucrose, glucose, and fructose are the main components of plant nectars. Intriguingly, honeybees express only 3 putative sugar receptors (AmGr1, AmGr2, and AmGr3), which is in stark contrast to many other insects and vertebrates. The sugar receptors are only partially characterized. AmGr1 detects different sugars including sucrose and glucose. AmGr2 is assumed to act as a co-receptor only, while AmGr3 is assumedly a fructose receptor. We show that honeybee gustatory receptor AmGr3 is highly specialized for fructose perception when expressed in Xenopus oocytes. When we introduced nonsense mutations to the respective AmGr3 gene using CRISPR/Cas9 in eggs of female workers, the resulting mutants displayed almost a complete loss of responsiveness to fructose. In contrast, responses to sucrose were normal. Nonsense mutations introduced by CRISPR/Cas9 in honeybees can thus induce a measurable behavioral change and serve to characterize the function of taste receptors in vivo. CRISPR/Cas9 is an excellent novel tool for characterizing honeybee taste receptors in vivo. Biophysical receptor characterization in Xenopus oocytes and nonsense mutation of AmGr3 in honeybees unequivocally demonstrate that this receptor is highly specific for fructose.

• Liu, Y., Maierhofer, T., Rybak, K., Sklenar, J., Breakspear, A., Johnston, M.G., Fliegmann, J., Huang, S., Roelfsema, M.R.G., Felix, G., Faulkner, C., Menke, F.L., Geiger, D., Hedrich, R., und Robatzek, S. (2019) „Anion channel SLAH3 is a regulatory target of chitin receptor-associated kinase PBL27 in microbial stomatal closure“, Elife, 8, verfügbar unter: https://doi.org/10.7554/eLife.44474.
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  In plants, antimicrobial immune responses involve the cellular release of anions and are responsible for the closure of stomatal pores. Detection of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) induces currents mediated via slow-type (S-type) anion channels by a yet not understood mechanism. Here, we show that stomatal closure to fungal chitin is conferred by the major PRRs for chitin recognition, LYK5 and CERK1, the receptor-like cytoplasmic kinase PBL27, and the SLAH3 anion channel. PBL27 has the capacity to phosphorylate SLAH3, of which S127 and S189 are required to activate SLAH3. Full activation of the channel entails CERK1, depending on PBL27. Importantly, both S127 and S189 residues of SLAH3 are required for chitin-induced stomatal closure and anti-fungal immunity at the whole leaf level. Our results demonstrate a short signal transduction module from MAMP recognition to anion channel activation, and independent of ABA-induced SLAH3 activation.

  @article{RN209, abstract = {In plants, antimicrobial immune responses involve the cellular release of anions and are responsible for the closure of stomatal pores. Detection of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) induces currents mediated via slow-type (S-type) anion channels by a yet not understood mechanism. Here, we show that stomatal closure to fungal chitin is conferred by the major PRRs for chitin recognition, LYK5 and CERK1, the receptor-like cytoplasmic kinase PBL27, and the SLAH3 anion channel. PBL27 has the capacity to phosphorylate SLAH3, of which S127 and S189 are required to activate SLAH3. Full activation of the channel entails CERK1, depending on PBL27. Importantly, both S127 and S189 residues of SLAH3 are required for chitin-induced stomatal closure and anti-fungal immunity at the whole leaf level. Our results demonstrate a short signal transduction module from MAMP recognition to anion channel activation, and independent of ABA-induced SLAH3 activation.}, author = {Liu, Y. and Maierhofer, T. and Rybak, K. and Sklenar, J. and Breakspear, A. and Johnston, M. G. and Fliegmann, J. and Huang, S. and Roelfsema, M. R. G. and Felix, G. and Faulkner, C. and Menke, F. L. and Geiger, D. and Hedrich, R. and Robatzek, S.}, journal = {Elife}, keywords = {myOwn}, note = {Liu, Yi Maierhofer, Tobias Rybak, Katarzyna Sklenar, Jan Breakspear, Andy Johnston, Matthew G Fliegmann, Judith Huang, Shouguang Roelfsema, M Rob G Felix, Georg Faulkner, Christine Menke, Frank Lh Geiger, Dietmar Hedrich, Rainer Robatzek, Silke 2019/9/17}, title = {Anion channel SLAH3 is a regulatory target of chitin receptor-associated kinase PBL27 in microbial stomatal closure}, type = {Journal Article}, volume = 8, year = 2019 }

  %0 Journal Article %1 RN209 %A Liu, Y. %A Maierhofer, T. %A Rybak, K. %A Sklenar, J. %A Breakspear, A. %A Johnston, M. G. %A Fliegmann, J. %A Huang, S. %A Roelfsema, M. R. G. %A Felix, G. %A Faulkner, C. %A Menke, F. L. %A Geiger, D. %A Hedrich, R. %A Robatzek, S. %D 2019 %J Elife %R 10.7554/eLife.44474 %T Anion channel SLAH3 is a regulatory target of chitin receptor-associated kinase PBL27 in microbial stomatal closure %U https://www.ncbi.nlm.nih.gov/pubmed/31524595 %V 8 %X In plants, antimicrobial immune responses involve the cellular release of anions and are responsible for the closure of stomatal pores. Detection of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs) induces currents mediated via slow-type (S-type) anion channels by a yet not understood mechanism. Here, we show that stomatal closure to fungal chitin is conferred by the major PRRs for chitin recognition, LYK5 and CERK1, the receptor-like cytoplasmic kinase PBL27, and the SLAH3 anion channel. PBL27 has the capacity to phosphorylate SLAH3, of which S127 and S189 are required to activate SLAH3. Full activation of the channel entails CERK1, depending on PBL27. Importantly, both S127 and S189 residues of SLAH3 are required for chitin-induced stomatal closure and anti-fungal immunity at the whole leaf level. Our results demonstrate a short signal transduction module from MAMP recognition to anion channel activation, and independent of ABA-induced SLAH3 activation.

• Batool, S., Uslu, V.V., Rajab, H., Ahmad, N., Waadt, R., Geiger, D., Malagoli, M., Xiang, C.B., Hedrich, R., Rennenberg, H., Herschbach, C., Hell, R., und Wirtz, M. (2018) „Sulfate is Incorporated into Cysteine to Trigger ABA Production and Stomatal Closure“, Plant Cell, 30(12), 2973–2987, verfügbar unter: https://doi.org/10.1105/tpc.18.00612.
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  Plants close stomata when root water availability becomes limiting. Recent studies have demonstrated that soil-drying induces root-to-shoot sulfate transport via the xylem and that sulfate closes stomata. Here we provide evidence for a physiologically relevant signaling pathway that underlies sulfate-induced stomatal closure in Arabidopsis (

  @article{RN210, abstract = {Plants close stomata when root water availability becomes limiting. Recent studies have demonstrated that soil-drying induces root-to-shoot sulfate transport via the xylem and that sulfate closes stomata. Here we provide evidence for a physiologically relevant signaling pathway that underlies sulfate-induced stomatal closure in Arabidopsis (}, author = {Batool, S. and Uslu, V. V. and Rajab, H. and Ahmad, N. and Waadt, R. and Geiger, D. and Malagoli, M. and Xiang, C. B. and Hedrich, R. and Rennenberg, H. and Herschbach, C. and Hell, R. and Wirtz, M.}, journal = {Plant Cell}, keywords = {myOwn}, note = {Batool, Sundas Uslu, Veli Vural Rajab, Hala Ahmad, Nisar Waadt, Rainer Geiger, Dietmar Malagoli, Mario Xiang, Cheng-Bin Hedrich, Rainer Rennenberg, Heinz Herschbach, Cornelia Hell, Ruediger Wirtz, Markus 2018/12/13}, number = 12, pages = {2973-2987}, title = {Sulfate is Incorporated into Cysteine to Trigger ABA Production and Stomatal Closure}, type = {Journal Article}, volume = 30, year = 2018 }

  %0 Journal Article %1 RN210 %A Batool, S. %A Uslu, V. V. %A Rajab, H. %A Ahmad, N. %A Waadt, R. %A Geiger, D. %A Malagoli, M. %A Xiang, C. B. %A Hedrich, R. %A Rennenberg, H. %A Herschbach, C. %A Hell, R. %A Wirtz, M. %D 2018 %J Plant Cell %N 12 %P 2973-2987 %R 10.1105/tpc.18.00612 %T Sulfate is Incorporated into Cysteine to Trigger ABA Production and Stomatal Closure %U https://www.ncbi.nlm.nih.gov/pubmed/30538155 %V 30 %X Plants close stomata when root water availability becomes limiting. Recent studies have demonstrated that soil-drying induces root-to-shoot sulfate transport via the xylem and that sulfate closes stomata. Here we provide evidence for a physiologically relevant signaling pathway that underlies sulfate-induced stomatal closure in Arabidopsis (
• Schäfer, N., Maierhofer, T., Herrmann, J., Jørgensen, M.E., Lind, C., von Meyer, K., Lautner, S., Fromm, J., Felder, M., Hetherington, A.M., Ache, P., Geiger, D., und Hedrich, R. (2018) „A Tandem Amino Acid Residue Motif in Guard Cell SLAC1 Anion Channel of Grasses Allows for the Control of Stomatal Aperture by Nitrate“, Curr Biol, 28(9), 1370–1379.e5, verfügbar unter: https://doi.org/10.1016/j.cub.2018.03.027.
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  The latest major group of plants to evolve were the grasses. These became important in the mid-Paleogene about 40 million years ago. During evolution, leaf CO

  @article{RN213, abstract = {The latest major group of plants to evolve were the grasses. These became important in the mid-Paleogene about 40 million years ago. During evolution, leaf CO}, author = {Schäfer, N. and Maierhofer, T. and Herrmann, J. and Jørgensen, M. E. and Lind, C. and von Meyer, K. and Lautner, S. and Fromm, J. and Felder, M. and Hetherington, A. M. and Ache, P. and Geiger, D. and Hedrich, R.}, journal = {Curr Biol}, keywords = {myOwn}, note = {Schäfer, Nadine Maierhofer, Tobias Herrmann, Johannes Jørgensen, Morten Egevang Lind, Christof von Meyer, Katharina Lautner, Silke Fromm, Jörg Felder, Marius Hetherington, Alistair M Ache, Peter Geiger, Dietmar Hedrich, Rainer 2018/5/1}, number = 9, pages = {1370-1379.e5}, title = {A Tandem Amino Acid Residue Motif in Guard Cell SLAC1 Anion Channel of Grasses Allows for the Control of Stomatal Aperture by Nitrate}, type = {Journal Article}, volume = 28, year = 2018 }

  %0 Journal Article %1 RN213 %A Schäfer, N. %A Maierhofer, T. %A Herrmann, J. %A Jørgensen, M. E. %A Lind, C. %A von Meyer, K. %A Lautner, S. %A Fromm, J. %A Felder, M. %A Hetherington, A. M. %A Ache, P. %A Geiger, D. %A Hedrich, R. %D 2018 %J Curr Biol %N 9 %P 1370-1379.e5 %R 10.1016/j.cub.2018.03.027 %T A Tandem Amino Acid Residue Motif in Guard Cell SLAC1 Anion Channel of Grasses Allows for the Control of Stomatal Aperture by Nitrate %U https://www.ncbi.nlm.nih.gov/pubmed/29706511 %V 28 %X The latest major group of plants to evolve were the grasses. These became important in the mid-Paleogene about 40 million years ago. During evolution, leaf CO
• Sierla, M., Hõrak, H., Overmyer, K., Waszczak, C., Yarmolinsky, D., Maierhofer, T., Vainonen, J.P., Salojärvi, J., Denessiouk, K., Laanemets, K., Tõldsepp, K., Vahisalu, T., Gauthier, A., Puukko, T., Paulin, L., Auvinen, P., Geiger, D., Hedrich, R., Kollist, H., und Kangasjärvi, J. (2018) „The Receptor-like Pseudokinase GHR1 Is Required for Stomatal Closure“, Plant Cell, 30(11), 2813–2837, verfügbar unter: https://doi.org/10.1105/tpc.18.00441.
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  Guard cells control the aperture of stomatal pores to balance photosynthetic carbon dioxide uptake with evaporative water loss. Stomatal closure is triggered by several stimuli that initiate complex signaling networks to govern the activity of ion channels. Activation of SLOW ANION CHANNEL1 (SLAC1) is central to the process of stomatal closure and requires the leucine-rich repeat receptor-like kinase (LRR-RLK) GUARD CELL HYDROGEN PEROXIDE-RESISTANT1 (GHR1), among other signaling components. Here, based on functional analysis of nine

  @article{RN211, abstract = {Guard cells control the aperture of stomatal pores to balance photosynthetic carbon dioxide uptake with evaporative water loss. Stomatal closure is triggered by several stimuli that initiate complex signaling networks to govern the activity of ion channels. Activation of SLOW ANION CHANNEL1 (SLAC1) is central to the process of stomatal closure and requires the leucine-rich repeat receptor-like kinase (LRR-RLK) GUARD CELL HYDROGEN PEROXIDE-RESISTANT1 (GHR1), among other signaling components. Here, based on functional analysis of nine}, author = {Sierla, M. and Hõrak, H. and Overmyer, K. and Waszczak, C. and Yarmolinsky, D. and Maierhofer, T. and Vainonen, J. P. and Salojärvi, J. and Denessiouk, K. and Laanemets, K. and Tõldsepp, K. and Vahisalu, T. and Gauthier, A. and Puukko, T. and Paulin, L. and Auvinen, P. and Geiger, D. and Hedrich, R. and Kollist, H. and Kangasjärvi, J.}, journal = {Plant Cell}, keywords = {myOwn}, note = {Sierla, Maija Hõrak, Hanna Overmyer, Kirk Waszczak, Cezary Yarmolinsky, Dmitry Maierhofer, Tobias Vainonen, Julia P Salojärvi, Jarkko Denessiouk, Konstantin Laanemets, Kristiina Tõldsepp, Kadri Vahisalu, Triin Gauthier, Adrien Puukko, Tuomas Paulin, Lars Auvinen, Petri Geiger, Dietmar Hedrich, Rainer Kollist, Hannes Kangasjärvi, Jaakko 2018/10/27}, number = 11, pages = {2813-2837}, title = {The Receptor-like Pseudokinase GHR1 Is Required for Stomatal Closure}, type = {Journal Article}, volume = 30, year = 2018 }

  %0 Journal Article %1 RN211 %A Sierla, M. %A Hõrak, H. %A Overmyer, K. %A Waszczak, C. %A Yarmolinsky, D. %A Maierhofer, T. %A Vainonen, J. P. %A Salojärvi, J. %A Denessiouk, K. %A Laanemets, K. %A Tõldsepp, K. %A Vahisalu, T. %A Gauthier, A. %A Puukko, T. %A Paulin, L. %A Auvinen, P. %A Geiger, D. %A Hedrich, R. %A Kollist, H. %A Kangasjärvi, J. %D 2018 %J Plant Cell %N 11 %P 2813-2837 %R 10.1105/tpc.18.00441 %T The Receptor-like Pseudokinase GHR1 Is Required for Stomatal Closure %U https://www.ncbi.nlm.nih.gov/pubmed/30361234 %V 30 %X Guard cells control the aperture of stomatal pores to balance photosynthetic carbon dioxide uptake with evaporative water loss. Stomatal closure is triggered by several stimuli that initiate complex signaling networks to govern the activity of ion channels. Activation of SLOW ANION CHANNEL1 (SLAC1) is central to the process of stomatal closure and requires the leucine-rich repeat receptor-like kinase (LRR-RLK) GUARD CELL HYDROGEN PEROXIDE-RESISTANT1 (GHR1), among other signaling components. Here, based on functional analysis of nine
• Hürter, A.L., Fort, S., Cottaz, S., Hedrich, R., Geiger, D., und Roelfsema, M.R.G. (2018) „Mycorrhizal lipochitinoligosaccharides (LCOs) depolarize root hairs of Medicago truncatula“, PLoS One, 13(5), e0198126, verfügbar unter: https://doi.org/10.1371/journal.pone.0198126.
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  Arbuscular Mycorrhiza and Root Nodule Symbiosis are symbiotic interactions with a high benefit for plant growth and crop production. Thus, it is of great interest to understand the developmental process of these symbioses in detail. We analysed very early symbiotic responses of Medicago truncatula root hair cells, by stimulation with lipochitinoligosaccharides specific for the induction of nodules (Nod-LCOs), or the interaction with mycorrhiza (Myc-LCOs). Intracellular micro electrodes were used, in combination with Ca2+ sensitive reporter dyes, to study the relations between cytosolic Ca2+ signals and membrane potential changes. We found that sulfated Myc- as well as Nod-LCOs initiate a membrane depolarization, which depends on the chemical composition of these signaling molecules, as well as the genotype of the plants that were studied. A successive application of sulfated Myc-LCOs and Nod-LCOs resulted only in a single transient depolarization, indicating that Myc-LCOs can repress plasma membrane responses to Nod-LCOs. In contrast to current models, the Nod-LCO-induced depolarization precedes changes in the cytosolic Ca2+ level of root hair cells. The Nod-LCO induced membrane depolarization thus is most likely independent of cytosolic Ca2+ signals and nuclear Ca2+ spiking.

  @article{RN212, abstract = {Arbuscular Mycorrhiza and Root Nodule Symbiosis are symbiotic interactions with a high benefit for plant growth and crop production. Thus, it is of great interest to understand the developmental process of these symbioses in detail. We analysed very early symbiotic responses of Medicago truncatula root hair cells, by stimulation with lipochitinoligosaccharides specific for the induction of nodules (Nod-LCOs), or the interaction with mycorrhiza (Myc-LCOs). Intracellular micro electrodes were used, in combination with Ca2+ sensitive reporter dyes, to study the relations between cytosolic Ca2+ signals and membrane potential changes. We found that sulfated Myc- as well as Nod-LCOs initiate a membrane depolarization, which depends on the chemical composition of these signaling molecules, as well as the genotype of the plants that were studied. A successive application of sulfated Myc-LCOs and Nod-LCOs resulted only in a single transient depolarization, indicating that Myc-LCOs can repress plasma membrane responses to Nod-LCOs. In contrast to current models, the Nod-LCO-induced depolarization precedes changes in the cytosolic Ca2+ level of root hair cells. The Nod-LCO induced membrane depolarization thus is most likely independent of cytosolic Ca2+ signals and nuclear Ca2+ spiking.}, author = {Hürter, A. L. and Fort, S. and Cottaz, S. and Hedrich, R. and Geiger, D. and Roelfsema, M. R. G.}, journal = {PLoS One}, keywords = {myOwn}, note = {Hürter, Anna-Lena Fort, Sébastien Cottaz, Sylvain Hedrich, Rainer Geiger, Dietmar Roelfsema, M Rob G 2018/6/1}, number = 5, pages = {e0198126}, title = {Mycorrhizal lipochitinoligosaccharides (LCOs) depolarize root hairs of Medicago truncatula}, type = {Journal Article}, volume = 13, year = 2018 }

  %0 Journal Article %1 RN212 %A Hürter, A. L. %A Fort, S. %A Cottaz, S. %A Hedrich, R. %A Geiger, D. %A Roelfsema, M. R. G. %D 2018 %J PLoS One %N 5 %P e0198126 %R 10.1371/journal.pone.0198126 %T Mycorrhizal lipochitinoligosaccharides (LCOs) depolarize root hairs of Medicago truncatula %U https://www.ncbi.nlm.nih.gov/pubmed/29851976 %V 13 %X Arbuscular Mycorrhiza and Root Nodule Symbiosis are symbiotic interactions with a high benefit for plant growth and crop production. Thus, it is of great interest to understand the developmental process of these symbioses in detail. We analysed very early symbiotic responses of Medicago truncatula root hair cells, by stimulation with lipochitinoligosaccharides specific for the induction of nodules (Nod-LCOs), or the interaction with mycorrhiza (Myc-LCOs). Intracellular micro electrodes were used, in combination with Ca2+ sensitive reporter dyes, to study the relations between cytosolic Ca2+ signals and membrane potential changes. We found that sulfated Myc- as well as Nod-LCOs initiate a membrane depolarization, which depends on the chemical composition of these signaling molecules, as well as the genotype of the plants that were studied. A successive application of sulfated Myc-LCOs and Nod-LCOs resulted only in a single transient depolarization, indicating that Myc-LCOs can repress plasma membrane responses to Nod-LCOs. In contrast to current models, the Nod-LCO-induced depolarization precedes changes in the cytosolic Ca2+ level of root hair cells. The Nod-LCO induced membrane depolarization thus is most likely independent of cytosolic Ca2+ signals and nuclear Ca2+ spiking.

• Wittek, A., Dreyer, I., Al-Rasheid, K.A.S., Sauer, N., Hedrich, R., und Geiger, D. (2017) „The fungal UmSrt1 and maize ZmSUT1 sucrose transporters battle for plant sugar resources“, J Integr Plant Biol, 59(6), 422–435, verfügbar unter: https://doi.org/10.1111/jipb.12535.
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  The biotrophic fungus Ustilago maydis causes corn smut disease, inducing tumor formation in its host Zea mays. Upon infection, the fungal hyphae invaginate the plasma membrane of infected maize cells, establishing an interface where pathogen and host are separated only by their plasma membranes. At this interface the fungal and maize sucrose transporters, UmSrt1 and ZmSUT1, compete for extracellular sucrose in the corn smut/maize pathosystem. Here we biophysically characterized ZmSUT1 and UmSrt1 in Xenopus oocytes with respect to their voltage-, pH- and substrate-dependence and determined affinities toward protons and sucrose. In contrast to ZmSUT1, UmSrt1 has a high affinity for sucrose and is relatively pH- and voltage-independent. Using these quantitative parameters, we developed a mathematical model to simulate the competition for extracellular sucrose at the contact zone between the fungus and the host plant. This approach revealed that UmSrt1 exploits the apoplastic sucrose resource, which forces the plant transporter into a sucrose export mode providing the fungus with sugar from the phloem. Importantly, the high sucrose concentration in the phloem appeared disadvantageous for the ZmSUT1, preventing sucrose recovery from the apoplastic space in the fungus/plant interface.

  @article{RN201, abstract = {The biotrophic fungus Ustilago maydis causes corn smut disease, inducing tumor formation in its host Zea mays. Upon infection, the fungal hyphae invaginate the plasma membrane of infected maize cells, establishing an interface where pathogen and host are separated only by their plasma membranes. At this interface the fungal and maize sucrose transporters, UmSrt1 and ZmSUT1, compete for extracellular sucrose in the corn smut/maize pathosystem. Here we biophysically characterized ZmSUT1 and UmSrt1 in Xenopus oocytes with respect to their voltage-, pH- and substrate-dependence and determined affinities toward protons and sucrose. In contrast to ZmSUT1, UmSrt1 has a high affinity for sucrose and is relatively pH- and voltage-independent. Using these quantitative parameters, we developed a mathematical model to simulate the competition for extracellular sucrose at the contact zone between the fungus and the host plant. This approach revealed that UmSrt1 exploits the apoplastic sucrose resource, which forces the plant transporter into a sucrose export mode providing the fungus with sugar from the phloem. Importantly, the high sucrose concentration in the phloem appeared disadvantageous for the ZmSUT1, preventing sucrose recovery from the apoplastic space in the fungus/plant interface.}, author = {Wittek, A. and Dreyer, I. and Al-Rasheid, K. A. S. and Sauer, N. and Hedrich, R. and Geiger, D.}, journal = {J Integr Plant Biol}, keywords = {myOwn}, number = 6, pages = {422-435}, title = {The fungal UmSrt1 and maize ZmSUT1 sucrose transporters battle for plant sugar resources}, type = {Journal Article}, volume = 59, year = 2017 }

  %0 Journal Article %1 RN201 %A Wittek, A. %A Dreyer, I. %A Al-Rasheid, K. A. S. %A Sauer, N. %A Hedrich, R. %A Geiger, D. %D 2017 %J J Integr Plant Biol %N 6 %P 422-435 %R 10.1111/jipb.12535 %T The fungal UmSrt1 and maize ZmSUT1 sucrose transporters battle for plant sugar resources %U https://www.ncbi.nlm.nih.gov/pubmed/28296205 %V 59 %X The biotrophic fungus Ustilago maydis causes corn smut disease, inducing tumor formation in its host Zea mays. Upon infection, the fungal hyphae invaginate the plasma membrane of infected maize cells, establishing an interface where pathogen and host are separated only by their plasma membranes. At this interface the fungal and maize sucrose transporters, UmSrt1 and ZmSUT1, compete for extracellular sucrose in the corn smut/maize pathosystem. Here we biophysically characterized ZmSUT1 and UmSrt1 in Xenopus oocytes with respect to their voltage-, pH- and substrate-dependence and determined affinities toward protons and sucrose. In contrast to ZmSUT1, UmSrt1 has a high affinity for sucrose and is relatively pH- and voltage-independent. Using these quantitative parameters, we developed a mathematical model to simulate the competition for extracellular sucrose at the contact zone between the fungus and the host plant. This approach revealed that UmSrt1 exploits the apoplastic sucrose resource, which forces the plant transporter into a sucrose export mode providing the fungus with sugar from the phloem. Importantly, the high sucrose concentration in the phloem appeared disadvantageous for the ZmSUT1, preventing sucrose recovery from the apoplastic space in the fungus/plant interface.
• Malcheska, F., Ahmad, A., Batool, S., Müller, H.M., Ludwig-Müller, J., Kreuzwieser, J., Randewig, D., Hänsch, R., Mendel, R.R., Hell, R., Wirtz, M., Geiger, D., Ache, P., Hedrich, R., Herschbach, C., und Rennenberg, H. (2017) „Drought-Enhanced Xylem Sap Sulfate Closes Stomata by Affecting ALMT12 and Guard Cell ABA Synthesis“, Plant Physiol, 174(2), 798–814, verfügbar unter: https://doi.org/10.1104/pp.16.01784.
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  Water limitation of plants causes stomatal closure to prevent water loss by transpiration. For this purpose, progressing soil water deficit is communicated from roots to shoots. Abscisic acid (ABA) is the key signal in stress-induced stomatal closure, but ABA as an early xylem-delivered signal is still a matter of debate. In this study, poplar plants (

  @article{RN202, abstract = {Water limitation of plants causes stomatal closure to prevent water loss by transpiration. For this purpose, progressing soil water deficit is communicated from roots to shoots. Abscisic acid (ABA) is the key signal in stress-induced stomatal closure, but ABA as an early xylem-delivered signal is still a matter of debate. In this study, poplar plants (}, author = {Malcheska, F. and Ahmad, A. and Batool, S. and Müller, H. M. and Ludwig-Müller, J. and Kreuzwieser, J. and Randewig, D. and Hänsch, R. and Mendel, R. R. and Hell, R. and Wirtz, M. and Geiger, D. and Ache, P. and Hedrich, R. and Herschbach, C. and Rennenberg, H.}, journal = {Plant Physiol}, keywords = {myOwn}, number = 2, pages = {798-814}, title = {Drought-Enhanced Xylem Sap Sulfate Closes Stomata by Affecting ALMT12 and Guard Cell ABA Synthesis}, type = {Journal Article}, volume = 174, year = 2017 }

  %0 Journal Article %1 RN202 %A Malcheska, F. %A Ahmad, A. %A Batool, S. %A Müller, H. M. %A Ludwig-Müller, J. %A Kreuzwieser, J. %A Randewig, D. %A Hänsch, R. %A Mendel, R. R. %A Hell, R. %A Wirtz, M. %A Geiger, D. %A Ache, P. %A Hedrich, R. %A Herschbach, C. %A Rennenberg, H. %D 2017 %J Plant Physiol %N 2 %P 798-814 %R 10.1104/pp.16.01784 %T Drought-Enhanced Xylem Sap Sulfate Closes Stomata by Affecting ALMT12 and Guard Cell ABA Synthesis %U https://www.ncbi.nlm.nih.gov/pubmed/28446637 %V 174 %X Water limitation of plants causes stomatal closure to prevent water loss by transpiration. For this purpose, progressing soil water deficit is communicated from roots to shoots. Abscisic acid (ABA) is the key signal in stress-induced stomatal closure, but ABA as an early xylem-delivered signal is still a matter of debate. In this study, poplar plants (
• Müller, H.M., Schäfer, N., Bauer, H., Geiger, D., Lautner, S., Fromm, J., Riederer, M., Bueno, A., Nussbaumer, T., Mayer, K., Alquraishi, S.A., Alfarhan, A.H., Neher, E., Al-Rasheid, K.A.S., Ache, P., und Hedrich, R. (2017) „The desert plant Phoenix dactylifera closes stomata via nitrate-regulated SLAC1 anion channel“, New Phytol, 216(1), 150–162, verfügbar unter: https://doi.org/10.1111/nph.14672.
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  Date palm Phoenix dactylifera is a desert crop well adapted to survive and produce fruits under extreme drought and heat. How are palms under such harsh environmental conditions able to limit transpirational water loss? Here, we analysed the cuticular waxes, stomata structure and function, and molecular biology of guard cells from P. dactylifera. To understand the stomatal response to the water stress phytohormone of the desert plant, we cloned the major elements necessary for guard cell fast abscisic acid (ABA) signalling and reconstituted this ABA signalosome in Xenopus oocytes. The PhoenixSLAC1-type anion channel is regulated by ABA kinase PdOST1. Energy-dispersive X-ray analysis (EDXA) demonstrated that date palm guard cells release chloride during stomatal closure. However, in Cl

  @article{RN199, abstract = {Date palm Phoenix dactylifera is a desert crop well adapted to survive and produce fruits under extreme drought and heat. How are palms under such harsh environmental conditions able to limit transpirational water loss? Here, we analysed the cuticular waxes, stomata structure and function, and molecular biology of guard cells from P. dactylifera. To understand the stomatal response to the water stress phytohormone of the desert plant, we cloned the major elements necessary for guard cell fast abscisic acid (ABA) signalling and reconstituted this ABA signalosome in Xenopus oocytes. The PhoenixSLAC1-type anion channel is regulated by ABA kinase PdOST1. Energy-dispersive X-ray analysis (EDXA) demonstrated that date palm guard cells release chloride during stomatal closure. However, in Cl}, author = {Müller, H. M. and Schäfer, N. and Bauer, H. and Geiger, D. and Lautner, S. and Fromm, J. and Riederer, M. and Bueno, A. and Nussbaumer, T. and Mayer, K. and Alquraishi, S. A. and Alfarhan, A. H. and Neher, E. and Al-Rasheid, K. A. S. and Ache, P. and Hedrich, R.}, journal = {New Phytol}, keywords = {myOwn}, number = 1, pages = {150-162}, title = {The desert plant Phoenix dactylifera closes stomata via nitrate-regulated SLAC1 anion channel}, type = {Journal Article}, volume = 216, year = 2017 }

  %0 Journal Article %1 RN199 %A Müller, H. M. %A Schäfer, N. %A Bauer, H. %A Geiger, D. %A Lautner, S. %A Fromm, J. %A Riederer, M. %A Bueno, A. %A Nussbaumer, T. %A Mayer, K. %A Alquraishi, S. A. %A Alfarhan, A. H. %A Neher, E. %A Al-Rasheid, K. A. S. %A Ache, P. %A Hedrich, R. %D 2017 %J New Phytol %N 1 %P 150-162 %R 10.1111/nph.14672 %T The desert plant Phoenix dactylifera closes stomata via nitrate-regulated SLAC1 anion channel %U https://www.ncbi.nlm.nih.gov/pubmed/28670699 %V 216 %X Date palm Phoenix dactylifera is a desert crop well adapted to survive and produce fruits under extreme drought and heat. How are palms under such harsh environmental conditions able to limit transpirational water loss? Here, we analysed the cuticular waxes, stomata structure and function, and molecular biology of guard cells from P. dactylifera. To understand the stomatal response to the water stress phytohormone of the desert plant, we cloned the major elements necessary for guard cell fast abscisic acid (ABA) signalling and reconstituted this ABA signalosome in Xenopus oocytes. The PhoenixSLAC1-type anion channel is regulated by ABA kinase PdOST1. Energy-dispersive X-ray analysis (EDXA) demonstrated that date palm guard cells release chloride during stomatal closure. However, in Cl
• Hedrich, R. und Geiger, D. (2017) „Biology of SLAC1-type anion channels - from nutrient uptake to stomatal closure“, New Phytol, 216(1), 46–61, verfügbar unter: https://doi.org/10.1111/nph.14685.
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  Contents 46 I. 46 II. 47 III. 50 IV. 53 V. 56 VI. 57 58 58 References 58 SUMMARY: Stomatal guard cells control leaf CO

  @article{RN200, abstract = {Contents 46 I. 46 II. 47 III. 50 IV. 53 V. 56 VI. 57 58 58 References 58 SUMMARY: Stomatal guard cells control leaf CO}, author = {Hedrich, R. and Geiger, D.}, journal = {New Phytol}, keywords = {myOwn}, number = 1, pages = {46-61}, title = {Biology of SLAC1-type anion channels - from nutrient uptake to stomatal closure}, type = {Journal Article}, volume = 216, year = 2017 }

  %0 Journal Article %1 RN200 %A Hedrich, R. %A Geiger, D. %D 2017 %J New Phytol %N 1 %P 46-61 %R 10.1111/nph.14685 %T Biology of SLAC1-type anion channels - from nutrient uptake to stomatal closure %U https://www.ncbi.nlm.nih.gov/pubmed/28722226 %V 216 %X Contents 46 I. 46 II. 47 III. 50 IV. 53 V. 56 VI. 57 58 58 References 58 SUMMARY: Stomatal guard cells control leaf CO

• Chintalapati, C., Keller, T., Mueller, T.D., Gorboulev, V., Schäfer, N., Zilkowski, I., Veyhl-Wichmann, M., Geiger, D., Groll, J., und Koepsell, H. (2016) „Protein RS1 (RSC1A1) Downregulates the Exocytotic Pathway of Glucose Transporter SGLT1 at Low Intracellular Glucose via Inhibition of Ornithine Decarboxylase“, Mol Pharmacol, 90(5), 508–521, verfügbar unter: https://doi.org/10.1124/mol.116.104521.
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  Na(+)-d-glucose cotransporter 1 (SGLT1) is rate-limiting for glucose absorption in the small intestine. Shortly after intake of glucose-rich food, SGLT1 abundance in the luminal membrane of the small intestine is increased. This upregulation occurs via glucose-induced acceleration of the release of SGLT1-containing vesicles from the trans-Golgi network (TGN), which is regulated by a domain of protein RS1 (RSC1A1) named RS1-Reg. Dependent on phosphorylation, RS1-Reg blocks release of vesicles containing SGLT1 or concentrative nucleoside transporter 1. The hypothesis has been raised that RS1-Reg binds to different receptor proteins at the TGN, which trigger release of vesicles with different transporters. To identify the presumed receptor proteins, two-hybrid screening was performed. Interaction with ornithine decarboxylase 1 (ODC1), the rate-limiting enzyme of polyamine synthesis, was observed and verified by immunoprecipitation. Binding of RS1-Reg mutants to ODC1 was characterized using surface plasmon resonance. Inhibition of ODC1 activity by RS1-Reg mutants and the ODC1 inhibitor difluoromethylornithine (DFMO) was measured in the absence and presence of glucose. In addition, short-term effects of DFMO, RS1-Reg mutants, the ODC1 product putrescine, and/or glucose on SGLT1 expressed in oocytes of Xenopus laevis were investigated. High-affinity binding of RS1-Reg to ODC1 was demonstrated, and evidence for a glucose binding site in ODC1 was provided. Binding of RS1-Reg to ODC1 inhibits the enzymatic activity at low intracellular glucose, which is blunted at high intracellular glucose. The data suggest that generation of putrescine by ODC1 at the TGN stimulates release of SGLT1-containing vesicles. This indicates a biomedically important role of ODC1 in regulation of glucose homeostasis.

  @article{RN198, abstract = {Na(+)-d-glucose cotransporter 1 (SGLT1) is rate-limiting for glucose absorption in the small intestine. Shortly after intake of glucose-rich food, SGLT1 abundance in the luminal membrane of the small intestine is increased. This upregulation occurs via glucose-induced acceleration of the release of SGLT1-containing vesicles from the trans-Golgi network (TGN), which is regulated by a domain of protein RS1 (RSC1A1) named RS1-Reg. Dependent on phosphorylation, RS1-Reg blocks release of vesicles containing SGLT1 or concentrative nucleoside transporter 1. The hypothesis has been raised that RS1-Reg binds to different receptor proteins at the TGN, which trigger release of vesicles with different transporters. To identify the presumed receptor proteins, two-hybrid screening was performed. Interaction with ornithine decarboxylase 1 (ODC1), the rate-limiting enzyme of polyamine synthesis, was observed and verified by immunoprecipitation. Binding of RS1-Reg mutants to ODC1 was characterized using surface plasmon resonance. Inhibition of ODC1 activity by RS1-Reg mutants and the ODC1 inhibitor difluoromethylornithine (DFMO) was measured in the absence and presence of glucose. In addition, short-term effects of DFMO, RS1-Reg mutants, the ODC1 product putrescine, and/or glucose on SGLT1 expressed in oocytes of Xenopus laevis were investigated. High-affinity binding of RS1-Reg to ODC1 was demonstrated, and evidence for a glucose binding site in ODC1 was provided. Binding of RS1-Reg to ODC1 inhibits the enzymatic activity at low intracellular glucose, which is blunted at high intracellular glucose. The data suggest that generation of putrescine by ODC1 at the TGN stimulates release of SGLT1-containing vesicles. This indicates a biomedically important role of ODC1 in regulation of glucose homeostasis.}, author = {Chintalapati, C. and Keller, T. and Mueller, T. D. and Gorboulev, V. and Schäfer, N. and Zilkowski, I. and Veyhl-Wichmann, M. and Geiger, D. and Groll, J. and Koepsell, H.}, journal = {Mol Pharmacol}, keywords = {myOwn}, number = 5, pages = {508-521}, title = {Protein RS1 (RSC1A1) Downregulates the Exocytotic Pathway of Glucose Transporter SGLT1 at Low Intracellular Glucose via Inhibition of Ornithine Decarboxylase}, type = {Journal Article}, volume = 90, year = 2016 }

  %0 Journal Article %1 RN198 %A Chintalapati, C. %A Keller, T. %A Mueller, T. D. %A Gorboulev, V. %A Schäfer, N. %A Zilkowski, I. %A Veyhl-Wichmann, M. %A Geiger, D. %A Groll, J. %A Koepsell, H. %D 2016 %J Mol Pharmacol %N 5 %P 508-521 %R 10.1124/mol.116.104521 %T Protein RS1 (RSC1A1) Downregulates the Exocytotic Pathway of Glucose Transporter SGLT1 at Low Intracellular Glucose via Inhibition of Ornithine Decarboxylase %U https://www.ncbi.nlm.nih.gov/pubmed/27555600 %V 90 %X Na(+)-d-glucose cotransporter 1 (SGLT1) is rate-limiting for glucose absorption in the small intestine. Shortly after intake of glucose-rich food, SGLT1 abundance in the luminal membrane of the small intestine is increased. This upregulation occurs via glucose-induced acceleration of the release of SGLT1-containing vesicles from the trans-Golgi network (TGN), which is regulated by a domain of protein RS1 (RSC1A1) named RS1-Reg. Dependent on phosphorylation, RS1-Reg blocks release of vesicles containing SGLT1 or concentrative nucleoside transporter 1. The hypothesis has been raised that RS1-Reg binds to different receptor proteins at the TGN, which trigger release of vesicles with different transporters. To identify the presumed receptor proteins, two-hybrid screening was performed. Interaction with ornithine decarboxylase 1 (ODC1), the rate-limiting enzyme of polyamine synthesis, was observed and verified by immunoprecipitation. Binding of RS1-Reg mutants to ODC1 was characterized using surface plasmon resonance. Inhibition of ODC1 activity by RS1-Reg mutants and the ODC1 inhibitor difluoromethylornithine (DFMO) was measured in the absence and presence of glucose. In addition, short-term effects of DFMO, RS1-Reg mutants, the ODC1 product putrescine, and/or glucose on SGLT1 expressed in oocytes of Xenopus laevis were investigated. High-affinity binding of RS1-Reg to ODC1 was demonstrated, and evidence for a glucose binding site in ODC1 was provided. Binding of RS1-Reg to ODC1 inhibits the enzymatic activity at low intracellular glucose, which is blunted at high intracellular glucose. The data suggest that generation of putrescine by ODC1 at the TGN stimulates release of SGLT1-containing vesicles. This indicates a biomedically important role of ODC1 in regulation of glucose homeostasis.
• Cubero-Font, P., Maierhofer, T., Jaslan, J., Rosales, M.A., Espartero, J., Díaz-Rueda, P., Müller, H.M., Hürter, A.L., Al-Rasheid, K.A., Marten, I., Hedrich, R., Colmenero-Flores, J.M., und Geiger, D. (2016) „Silent S-Type Anion Channel Subunit SLAH1 Gates SLAH3 Open for Chloride Root-to-Shoot Translocation“, Curr Biol, 26(16), 2213–20, verfügbar unter: https://doi.org/10.1016/j.cub.2016.06.045.
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  Higher plants take up nutrients via the roots and load them into xylem vessels for translocation to the shoot. After uptake, anions have to be channeled toward the root xylem vessels. Thereby, xylem parenchyma and pericycle cells control the anion composition of the root-shoot xylem sap [1-6]. The fact that salt-tolerant genotypes possess lower xylem-sap Cl(-) contents compared to salt-sensitive genotypes [7-10] indicates that membrane transport proteins at the sites of xylem loading contribute to plant salinity tolerance via selective chloride exclusion. However, the molecular mechanism of xylem loading that lies behind the balance between NO3(-) and Cl(-) loading remains largely unknown. Here we identify two root anion channels in Arabidopsis, SLAH1 and SLAH3, that control the shoot NO3(-)/Cl(-) ratio. The AtSLAH1 gene is expressed in the root xylem-pole pericycle, where it co-localizes with AtSLAH3. Under high soil salinity, AtSLAH1 expression markedly declined and the chloride content of the xylem sap in AtSLAH1 loss-of-function mutants was half of the wild-type level only. SLAH3 anion channels are not active per se but require extracellular nitrate and phosphorylation by calcium-dependent kinases (CPKs) [11-13]. When co-expressed in Xenopus oocytes, however, the electrically silent SLAH1 subunit gates SLAH3 open even in the absence of nitrate- and calcium-dependent kinases. Apparently, SLAH1/SLAH3 heteromerization facilitates SLAH3-mediated chloride efflux from pericycle cells into the root xylem vessels. Our results indicate that under salt stress, plants adjust the distribution of NO3(-) and Cl(-) between root and shoot via differential expression and assembly of SLAH1/SLAH3 anion channel subunits.

  @article{RN196, abstract = {Higher plants take up nutrients via the roots and load them into xylem vessels for translocation to the shoot. After uptake, anions have to be channeled toward the root xylem vessels. Thereby, xylem parenchyma and pericycle cells control the anion composition of the root-shoot xylem sap [1-6]. The fact that salt-tolerant genotypes possess lower xylem-sap Cl(-) contents compared to salt-sensitive genotypes [7-10] indicates that membrane transport proteins at the sites of xylem loading contribute to plant salinity tolerance via selective chloride exclusion. However, the molecular mechanism of xylem loading that lies behind the balance between NO3(-) and Cl(-) loading remains largely unknown. Here we identify two root anion channels in Arabidopsis, SLAH1 and SLAH3, that control the shoot NO3(-)/Cl(-) ratio. The AtSLAH1 gene is expressed in the root xylem-pole pericycle, where it co-localizes with AtSLAH3. Under high soil salinity, AtSLAH1 expression markedly declined and the chloride content of the xylem sap in AtSLAH1 loss-of-function mutants was half of the wild-type level only. SLAH3 anion channels are not active per se but require extracellular nitrate and phosphorylation by calcium-dependent kinases (CPKs) [11-13]. When co-expressed in Xenopus oocytes, however, the electrically silent SLAH1 subunit gates SLAH3 open even in the absence of nitrate- and calcium-dependent kinases. Apparently, SLAH1/SLAH3 heteromerization facilitates SLAH3-mediated chloride efflux from pericycle cells into the root xylem vessels. Our results indicate that under salt stress, plants adjust the distribution of NO3(-) and Cl(-) between root and shoot via differential expression and assembly of SLAH1/SLAH3 anion channel subunits.}, author = {Cubero-Font, P. and Maierhofer, T. and Jaslan, J. and Rosales, M. A. and Espartero, J. and Díaz-Rueda, P. and Müller, H. M. and Hürter, A. L. and Al-Rasheid, K. A. and Marten, I. and Hedrich, R. and Colmenero-Flores, J. M. and Geiger, D.}, journal = {Curr Biol}, keywords = {myOwn}, number = 16, pages = {2213-20}, title = {Silent S-Type Anion Channel Subunit SLAH1 Gates SLAH3 Open for Chloride Root-to-Shoot Translocation}, type = {Journal Article}, volume = 26, year = 2016 }

  %0 Journal Article %1 RN196 %A Cubero-Font, P. %A Maierhofer, T. %A Jaslan, J. %A Rosales, M. A. %A Espartero, J. %A Díaz-Rueda, P. %A Müller, H. M. %A Hürter, A. L. %A Al-Rasheid, K. A. %A Marten, I. %A Hedrich, R. %A Colmenero-Flores, J. M. %A Geiger, D. %D 2016 %J Curr Biol %N 16 %P 2213-20 %R 10.1016/j.cub.2016.06.045 %T Silent S-Type Anion Channel Subunit SLAH1 Gates SLAH3 Open for Chloride Root-to-Shoot Translocation %U https://www.ncbi.nlm.nih.gov/pubmed/27397895 %V 26 %X Higher plants take up nutrients via the roots and load them into xylem vessels for translocation to the shoot. After uptake, anions have to be channeled toward the root xylem vessels. Thereby, xylem parenchyma and pericycle cells control the anion composition of the root-shoot xylem sap [1-6]. The fact that salt-tolerant genotypes possess lower xylem-sap Cl(-) contents compared to salt-sensitive genotypes [7-10] indicates that membrane transport proteins at the sites of xylem loading contribute to plant salinity tolerance via selective chloride exclusion. However, the molecular mechanism of xylem loading that lies behind the balance between NO3(-) and Cl(-) loading remains largely unknown. Here we identify two root anion channels in Arabidopsis, SLAH1 and SLAH3, that control the shoot NO3(-)/Cl(-) ratio. The AtSLAH1 gene is expressed in the root xylem-pole pericycle, where it co-localizes with AtSLAH3. Under high soil salinity, AtSLAH1 expression markedly declined and the chloride content of the xylem sap in AtSLAH1 loss-of-function mutants was half of the wild-type level only. SLAH3 anion channels are not active per se but require extracellular nitrate and phosphorylation by calcium-dependent kinases (CPKs) [11-13]. When co-expressed in Xenopus oocytes, however, the electrically silent SLAH1 subunit gates SLAH3 open even in the absence of nitrate- and calcium-dependent kinases. Apparently, SLAH1/SLAH3 heteromerization facilitates SLAH3-mediated chloride efflux from pericycle cells into the root xylem vessels. Our results indicate that under salt stress, plants adjust the distribution of NO3(-) and Cl(-) between root and shoot via differential expression and assembly of SLAH1/SLAH3 anion channel subunits.
• McAdam, S.A., Brodribb, T.J., Banks, J.A., Hedrich, R., Atallah, N.M., Cai, C., Geringer, M.A., Lind, C., Nichols, D.S., Stachowski, K., Geiger, D., und Sussmilch, F.C. (2016) „Abscisic acid controlled sex before transpiration in vascular plants“, Proc Natl Acad Sci U S A, verfügbar unter: https://doi.org/10.1073/pnas.1606614113.
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  Sexual reproduction in animals and plants shares common elements, including sperm and egg production, but unlike animals, little is known about the regulatory pathways that determine the sex of plants. Here we use mutants and gene silencing in a fern species to identify a core regulatory mechanism in plant sexual differentiation. A key player in fern sex differentiation is the phytohormone abscisic acid (ABA), which regulates the sex ratio of male to hermaphrodite tissues during the reproductive cycle. Our analysis shows that in the fern Ceratopteris richardii, a gene homologous to core ABA transduction genes in flowering plants [SNF1-related kinase2s (SnRK2s)] is primarily responsible for the hormonal control of sex determination. Furthermore, we provide evidence that this ABA-SnRK2 signaling pathway has transitioned from determining the sex of ferns to controlling seed dormancy in the earliest seed plants before being co-opted to control transpiration and CO2 exchange in derived seed plants. By tracing the evolutionary history of this ABA signaling pathway from plant reproduction through to its role in the global regulation of plant-atmosphere gas exchange during the last 450 million years, we highlight the extraordinary effect of the ABA-SnRK2 signaling pathway in plant evolution and vegetation function.

  @article{RN197, abstract = {Sexual reproduction in animals and plants shares common elements, including sperm and egg production, but unlike animals, little is known about the regulatory pathways that determine the sex of plants. Here we use mutants and gene silencing in a fern species to identify a core regulatory mechanism in plant sexual differentiation. A key player in fern sex differentiation is the phytohormone abscisic acid (ABA), which regulates the sex ratio of male to hermaphrodite tissues during the reproductive cycle. Our analysis shows that in the fern Ceratopteris richardii, a gene homologous to core ABA transduction genes in flowering plants [SNF1-related kinase2s (SnRK2s)] is primarily responsible for the hormonal control of sex determination. Furthermore, we provide evidence that this ABA-SnRK2 signaling pathway has transitioned from determining the sex of ferns to controlling seed dormancy in the earliest seed plants before being co-opted to control transpiration and CO2 exchange in derived seed plants. By tracing the evolutionary history of this ABA signaling pathway from plant reproduction through to its role in the global regulation of plant-atmosphere gas exchange during the last 450 million years, we highlight the extraordinary effect of the ABA-SnRK2 signaling pathway in plant evolution and vegetation function.}, author = {McAdam, S. A. and Brodribb, T. J. and Banks, J. A. and Hedrich, R. and Atallah, N. M. and Cai, C. and Geringer, M. A. and Lind, C. and Nichols, D. S. and Stachowski, K. and Geiger, D. and Sussmilch, F. C.}, journal = {Proc Natl Acad Sci U S A}, keywords = {myOwn}, title = {Abscisic acid controlled sex before transpiration in vascular plants}, type = {Journal Article}, year = 2016 }

  %0 Journal Article %1 RN197 %A McAdam, S. A. %A Brodribb, T. J. %A Banks, J. A. %A Hedrich, R. %A Atallah, N. M. %A Cai, C. %A Geringer, M. A. %A Lind, C. %A Nichols, D. S. %A Stachowski, K. %A Geiger, D. %A Sussmilch, F. C. %D 2016 %J Proc Natl Acad Sci U S A %R 10.1073/pnas.1606614113 %T Abscisic acid controlled sex before transpiration in vascular plants %U https://www.ncbi.nlm.nih.gov/pubmed/27791082 %X Sexual reproduction in animals and plants shares common elements, including sperm and egg production, but unlike animals, little is known about the regulatory pathways that determine the sex of plants. Here we use mutants and gene silencing in a fern species to identify a core regulatory mechanism in plant sexual differentiation. A key player in fern sex differentiation is the phytohormone abscisic acid (ABA), which regulates the sex ratio of male to hermaphrodite tissues during the reproductive cycle. Our analysis shows that in the fern Ceratopteris richardii, a gene homologous to core ABA transduction genes in flowering plants [SNF1-related kinase2s (SnRK2s)] is primarily responsible for the hormonal control of sex determination. Furthermore, we provide evidence that this ABA-SnRK2 signaling pathway has transitioned from determining the sex of ferns to controlling seed dormancy in the earliest seed plants before being co-opted to control transpiration and CO2 exchange in derived seed plants. By tracing the evolutionary history of this ABA signaling pathway from plant reproduction through to its role in the global regulation of plant-atmosphere gas exchange during the last 450 million years, we highlight the extraordinary effect of the ABA-SnRK2 signaling pathway in plant evolution and vegetation function.
• Jaborsky, M., Maierhofer, T., Olbrich, A., Escalante-Pérez, M., Müller, H.M., Simon, J., Krol, E., Cuin, T.A., Fromm, J., Ache, P., Geiger, D., und Hedrich, R. (2016) „SLAH3-type anion channel expressed in poplar secretory epithelia operates in calcium kinase CPK-autonomous manner“, New Phytol, 210(3), 922–33, verfügbar unter: https://doi.org/10.1111/nph.13841.
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  Extrafloral nectaries secrete a sweet sugar cocktail that lures predator insects for protection from foraging herbivores. Apart from sugars and amino acids, the nectar contains the anions chloride and nitrate. Recent studies with Populus have identified a type of nectary covered by apical bipolar epidermal cells, reminiscent of the secretory brush border epithelium in animals. Border epithelia operate transepithelial anion transport, which is required for membrane potential and/or osmotic adjustment of the secretory cells. In search of anion transporters expressed in extrafloral nectaries, we identified PttSLAH3 (Populus tremula × Populus tremuloides SLAC1 Homologue3), an anion channel of the SLAC/SLAH family. When expressed in Xenopus oocytes, PttSLAH3 displayed the features of a voltage-dependent anion channel, permeable to both nitrate and chloride. In contrast to the Arabidopsis SLAC/SLAH family members, the poplar isoform PttSLAH3 is independent of phosphorylation activation by protein kinases. To understand the basis for the autonomous activity of the poplar SLAH3, we generated and expressed chimera between kinase-independent PttSLAH3 and kinase-dependent Arabidopsis AtSLAH3. We identified the N-terminal tail and, to a lesser extent, the C-terminal tail as responsible for PttSLAH3 kinase-(in)dependent action. This feature of PttSLAH3 may provide the secretory cell with a channel probably controlling long-term nectar secretion.

  @article{RN203, abstract = {Extrafloral nectaries secrete a sweet sugar cocktail that lures predator insects for protection from foraging herbivores. Apart from sugars and amino acids, the nectar contains the anions chloride and nitrate. Recent studies with Populus have identified a type of nectary covered by apical bipolar epidermal cells, reminiscent of the secretory brush border epithelium in animals. Border epithelia operate transepithelial anion transport, which is required for membrane potential and/or osmotic adjustment of the secretory cells. In search of anion transporters expressed in extrafloral nectaries, we identified PttSLAH3 (Populus tremula × Populus tremuloides SLAC1 Homologue3), an anion channel of the SLAC/SLAH family. When expressed in Xenopus oocytes, PttSLAH3 displayed the features of a voltage-dependent anion channel, permeable to both nitrate and chloride. In contrast to the Arabidopsis SLAC/SLAH family members, the poplar isoform PttSLAH3 is independent of phosphorylation activation by protein kinases. To understand the basis for the autonomous activity of the poplar SLAH3, we generated and expressed chimera between kinase-independent PttSLAH3 and kinase-dependent Arabidopsis AtSLAH3. We identified the N-terminal tail and, to a lesser extent, the C-terminal tail as responsible for PttSLAH3 kinase-(in)dependent action. This feature of PttSLAH3 may provide the secretory cell with a channel probably controlling long-term nectar secretion.}, author = {Jaborsky, M. and Maierhofer, T. and Olbrich, A. and Escalante-Pérez, M. and Müller, H. M. and Simon, J. and Krol, E. and Cuin, T. A. and Fromm, J. and Ache, P. and Geiger, D. and Hedrich, R.}, journal = {New Phytol}, keywords = {myOwn}, number = 3, pages = {922-33}, title = {SLAH3-type anion channel expressed in poplar secretory epithelia operates in calcium kinase CPK-autonomous manner}, type = {Journal Article}, volume = 210, year = 2016 }

  %0 Journal Article %1 RN203 %A Jaborsky, M. %A Maierhofer, T. %A Olbrich, A. %A Escalante-Pérez, M. %A Müller, H. M. %A Simon, J. %A Krol, E. %A Cuin, T. A. %A Fromm, J. %A Ache, P. %A Geiger, D. %A Hedrich, R. %D 2016 %J New Phytol %N 3 %P 922-33 %R 10.1111/nph.13841 %T SLAH3-type anion channel expressed in poplar secretory epithelia operates in calcium kinase CPK-autonomous manner %U https://www.ncbi.nlm.nih.gov/pubmed/26831448 %V 210 %X Extrafloral nectaries secrete a sweet sugar cocktail that lures predator insects for protection from foraging herbivores. Apart from sugars and amino acids, the nectar contains the anions chloride and nitrate. Recent studies with Populus have identified a type of nectary covered by apical bipolar epidermal cells, reminiscent of the secretory brush border epithelium in animals. Border epithelia operate transepithelial anion transport, which is required for membrane potential and/or osmotic adjustment of the secretory cells. In search of anion transporters expressed in extrafloral nectaries, we identified PttSLAH3 (Populus tremula × Populus tremuloides SLAC1 Homologue3), an anion channel of the SLAC/SLAH family. When expressed in Xenopus oocytes, PttSLAH3 displayed the features of a voltage-dependent anion channel, permeable to both nitrate and chloride. In contrast to the Arabidopsis SLAC/SLAH family members, the poplar isoform PttSLAH3 is independent of phosphorylation activation by protein kinases. To understand the basis for the autonomous activity of the poplar SLAH3, we generated and expressed chimera between kinase-independent PttSLAH3 and kinase-dependent Arabidopsis AtSLAH3. We identified the N-terminal tail and, to a lesser extent, the C-terminal tail as responsible for PttSLAH3 kinase-(in)dependent action. This feature of PttSLAH3 may provide the secretory cell with a channel probably controlling long-term nectar secretion.

• ME, J., CE, O., D, G., BA, H., und HH, N.-E. (2015) „A Functional EXXEK Motif is Essential for Proton-Coupling and Active Glucosinolate Transport by NPF2.11.“, verfügbar unter: http://europepmc.org/abstract/med/26443378.
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  @article{RN195, author = {ME, Jørgensen and CE, Olsen and D, Geiger and BA, Halkier and HH, Nour-Eldin}, keywords = {myOwn}, note = {ORCID Reference type: [formatted-unspecified]; ORCID Reference: [Jørgensen ME, Olsen CE, Geiger D, Halkier BA, Nour-Eldin HH, Plant & cell physiology, 2015]}, title = {A Functional EXXEK Motif is Essential for Proton-Coupling and Active Glucosinolate Transport by NPF2.11.}, type = {Journal Article}, year = 2015 }

  %0 Journal Article %1 RN195 %A ME, Jørgensen %A CE, Olsen %A D, Geiger %A BA, Halkier %A HH, Nour-Eldin %D 2015 %T A Functional EXXEK Motif is Essential for Proton-Coupling and Active Glucosinolate Transport by NPF2.11. %U http://europepmc.org/abstract/med/26443378
• C, L., I, D., EJ, L.-S., K, von M., K, I., T, K., D, L., Y, Z., I, K., KA, A.-R., H, R., R, R., JK, Z., D, G., und R, H. (2015) „Stomatal Guard Cells Co-opted an Ancient ABA-Dependent Desiccation Survival System to Regulate Stomatal Closure.“, verfügbar unter: https://doi.org/10.1016/j.cub.2015.01.067.
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  @article{RN194, author = {C, Lind and I, Dreyer and EJ, López-Sanjurjo and K, von Meyer and K, Ishizaki and T, Kohchi and D, Lang and Y, Zhao and I, Kreuzer and KA, Al-Rasheid and H, Ronne and R, Reski and JK, Zhu and D, Geiger and R, Hedrich}, keywords = {myOwn}, note = {ORCID Reference type: [formatted-unspecified]; ORCID Reference: [Lind C, Dreyer I, López-Sanjurjo EJ, von Meyer K, Ishizaki K, Kohchi T, Lang D, Zhao Y, Kreuzer I, Al-Rasheid KA, Ronne H, Reski R, Zhu JK, Geiger D, Hedrich R, Current biology : CB, 2015, vol. 25, no. 7, pp. 928-935]}, title = {Stomatal Guard Cells Co-opted an Ancient ABA-Dependent Desiccation Survival System to Regulate Stomatal Closure.}, type = {Journal Article}, year = 2015 }

  %0 Journal Article %1 RN194 %A C, Lind %A I, Dreyer %A EJ, López-Sanjurjo %A K, von Meyer %A K, Ishizaki %A T, Kohchi %A D, Lang %A Y, Zhao %A I, Kreuzer %A KA, Al-Rasheid %A H, Ronne %A R, Reski %A JK, Zhu %A D, Geiger %A R, Hedrich %D 2015 %R 10.1016/j.cub.2015.01.067 %T Stomatal Guard Cells Co-opted an Ancient ABA-Dependent Desiccation Survival System to Regulate Stomatal Closure. %U http://europepmc.org/abstract/med/25802151

• Maierhofer, T., Diekmann, M., Offenborn, J.N., Lind, C., Bauer, H., Hashimoto, K., S Al-Rasheid, K.A., Luan, S., Kudla, J., Geiger, D., und Hedrich, R. (2014) „Site- and kinase-specific phosphorylation-mediated activation of SLAC1, a guard cell anion channel stimulated by abscisic acid“, Sci Signal, 7(342), ra86, verfügbar unter: https://doi.org/10.1126/scisignal.2005703.
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  Under drought stress, abscisic acid (ABA) triggers closure of leaf cell pores called stomata, which are formed by two specialized cells called guard cells in plant epidermis. Two pathways downstream of ABA stimulate phosphorylation of the S-type anion channels SLAC1 (slow anion channel associated 1) and SLAH3 (SLAC1 homolog 3), which causes these channels to open, reducing guard cell volume and triggering stomatal closure. One branch involves OST1 (open stomata 1), a calcium-independent SnRK2-type kinase, and the other branch involves calcium-dependent protein kinases of the CPK (calcium-dependent protein kinase) family. We used coexpression analyses in Xenopus oocytes to show that the calcineurin B-like (CBL) calcium sensors CBL1 and CBL9 and their interacting protein kinase CIPK23 also triggered SLAC1 and SLAH3 opening. We analyzed whether regulation of SLAC1 opening by these different families of kinases involved the same or different sites on SLAC1 by measuring channel conductance of SLAC1 with mutations in the putative phosphorylation sites in the amino or carboxyl termini coexpressed with specific kinases in Xenopus oocytes. SLAC1 mutants lacking the OST1-phosphorylated site were still activated by CPK or by CBL/CIPK complexes. Phosphorylation and activation of SLAC1 by any of the kinases were inhibited by the phosphatase ABI1 (ABA insensitive 1), which is inactivated in response to ABA signaling. These findings identified CBL/CIPK complexes as potential regulators of stomatal aperture through S-type anion channels and indicated that phosphorylation at distinct sites enables SLAC1 activation by both calcium-dependent and calcium-independent pathways downstream of ABA.

  @article{RN181, abstract = {Under drought stress, abscisic acid (ABA) triggers closure of leaf cell pores called stomata, which are formed by two specialized cells called guard cells in plant epidermis. Two pathways downstream of ABA stimulate phosphorylation of the S-type anion channels SLAC1 (slow anion channel associated 1) and SLAH3 (SLAC1 homolog 3), which causes these channels to open, reducing guard cell volume and triggering stomatal closure. One branch involves OST1 (open stomata 1), a calcium-independent SnRK2-type kinase, and the other branch involves calcium-dependent protein kinases of the CPK (calcium-dependent protein kinase) family. We used coexpression analyses in Xenopus oocytes to show that the calcineurin B-like (CBL) calcium sensors CBL1 and CBL9 and their interacting protein kinase CIPK23 also triggered SLAC1 and SLAH3 opening. We analyzed whether regulation of SLAC1 opening by these different families of kinases involved the same or different sites on SLAC1 by measuring channel conductance of SLAC1 with mutations in the putative phosphorylation sites in the amino or carboxyl termini coexpressed with specific kinases in Xenopus oocytes. SLAC1 mutants lacking the OST1-phosphorylated site were still activated by CPK or by CBL/CIPK complexes. Phosphorylation and activation of SLAC1 by any of the kinases were inhibited by the phosphatase ABI1 (ABA insensitive 1), which is inactivated in response to ABA signaling. These findings identified CBL/CIPK complexes as potential regulators of stomatal aperture through S-type anion channels and indicated that phosphorylation at distinct sites enables SLAC1 activation by both calcium-dependent and calcium-independent pathways downstream of ABA.}, author = {Maierhofer, T. and Diekmann, M. and Offenborn, J. N. and Lind, C. and Bauer, H. and Hashimoto, K. and S Al-Rasheid, K. A. and Luan, S. and Kudla, J. and Geiger, D. and Hedrich, R.}, journal = {Sci Signal}, keywords = {myOwn}, number = 342, pages = {ra86}, title = {Site- and kinase-specific phosphorylation-mediated activation of SLAC1, a guard cell anion channel stimulated by abscisic acid}, type = {Journal Article}, volume = 7, year = 2014 }

  %0 Journal Article %1 RN181 %A Maierhofer, T. %A Diekmann, M. %A Offenborn, J. N. %A Lind, C. %A Bauer, H. %A Hashimoto, K. %A S Al-Rasheid, K. A. %A Luan, S. %A Kudla, J. %A Geiger, D. %A Hedrich, R. %D 2014 %J Sci Signal %N 342 %P ra86 %R 10.1126/scisignal.2005703 %T Site- and kinase-specific phosphorylation-mediated activation of SLAC1, a guard cell anion channel stimulated by abscisic acid %U http://www.ncbi.nlm.nih.gov/pubmed/25205850 %V 7 %X Under drought stress, abscisic acid (ABA) triggers closure of leaf cell pores called stomata, which are formed by two specialized cells called guard cells in plant epidermis. Two pathways downstream of ABA stimulate phosphorylation of the S-type anion channels SLAC1 (slow anion channel associated 1) and SLAH3 (SLAC1 homolog 3), which causes these channels to open, reducing guard cell volume and triggering stomatal closure. One branch involves OST1 (open stomata 1), a calcium-independent SnRK2-type kinase, and the other branch involves calcium-dependent protein kinases of the CPK (calcium-dependent protein kinase) family. We used coexpression analyses in Xenopus oocytes to show that the calcineurin B-like (CBL) calcium sensors CBL1 and CBL9 and their interacting protein kinase CIPK23 also triggered SLAC1 and SLAH3 opening. We analyzed whether regulation of SLAC1 opening by these different families of kinases involved the same or different sites on SLAC1 by measuring channel conductance of SLAC1 with mutations in the putative phosphorylation sites in the amino or carboxyl termini coexpressed with specific kinases in Xenopus oocytes. SLAC1 mutants lacking the OST1-phosphorylated site were still activated by CPK or by CBL/CIPK complexes. Phosphorylation and activation of SLAC1 by any of the kinases were inhibited by the phosphatase ABI1 (ABA insensitive 1), which is inactivated in response to ABA signaling. These findings identified CBL/CIPK complexes as potential regulators of stomatal aperture through S-type anion channels and indicated that phosphorylation at distinct sites enables SLAC1 activation by both calcium-dependent and calcium-independent pathways downstream of ABA.
• Léran, S., Varala, K., Boyer, J.C., Chiurazzi, M., Crawford, N., Daniel-Vedele, F., David, L., Dickstein, R., Fernandez, E., Forde, B., Gassmann, W., Geiger, D., Gojon, A., Gong, J.M., Halkier, B.A., Harris, J.M., Hedrich, R., Limami, A.M., Rentsch, D., Seo, M., Tsay, Y.F., Zhang, M., Coruzzi, G., und Lacombe, B. (2014) „A unified nomenclature of NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER family members in plants“, Trends Plant Sci, 19(1), 5–9, verfügbar unter: https://doi.org/10.1016/j.tplants.2013.08.008.
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  Members of the plant NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER (NRT1/PTR) family display protein sequence homology with the SLC15/PepT/PTR/POT family of peptide transporters in animals. In comparison to their animal and bacterial counterparts, these plant proteins transport a wide variety of substrates: nitrate, peptides, amino acids, dicarboxylates, glucosinolates, IAA, and ABA. The phylogenetic relationship of the members of the NRT1/PTR family in 31 fully sequenced plant genomes allowed the identification of unambiguous clades, defining eight subfamilies. The phylogenetic tree was used to determine a unified nomenclature of this family named NPF, for NRT1/PTR FAMILY. We propose that the members should be named accordingly: NPFX.Y, where X denotes the subfamily and Y the individual member within the species.

  @article{RN183, abstract = {Members of the plant NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER (NRT1/PTR) family display protein sequence homology with the SLC15/PepT/PTR/POT family of peptide transporters in animals. In comparison to their animal and bacterial counterparts, these plant proteins transport a wide variety of substrates: nitrate, peptides, amino acids, dicarboxylates, glucosinolates, IAA, and ABA. The phylogenetic relationship of the members of the NRT1/PTR family in 31 fully sequenced plant genomes allowed the identification of unambiguous clades, defining eight subfamilies. The phylogenetic tree was used to determine a unified nomenclature of this family named NPF, for NRT1/PTR FAMILY. We propose that the members should be named accordingly: NPFX.Y, where X denotes the subfamily and Y the individual member within the species.}, author = {Léran, S. and Varala, K. and Boyer, J. C. and Chiurazzi, M. and Crawford, N. and Daniel-Vedele, F. and David, L. and Dickstein, R. and Fernandez, E. and Forde, B. and Gassmann, W. and Geiger, D. and Gojon, A. and Gong, J. M. and Halkier, B. A. and Harris, J. M. and Hedrich, R. and Limami, A. M. and Rentsch, D. and Seo, M. and Tsay, Y. F. and Zhang, M. and Coruzzi, G. and Lacombe, B.}, journal = {Trends Plant Sci}, keywords = {myOwn}, number = 1, pages = {5-9}, title = {A unified nomenclature of NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER family members in plants}, type = {Journal Article}, volume = 19, year = 2014 }

  %0 Journal Article %1 RN183 %A Léran, S. %A Varala, K. %A Boyer, J. C. %A Chiurazzi, M. %A Crawford, N. %A Daniel-Vedele, F. %A David, L. %A Dickstein, R. %A Fernandez, E. %A Forde, B. %A Gassmann, W. %A Geiger, D. %A Gojon, A. %A Gong, J. M. %A Halkier, B. A. %A Harris, J. M. %A Hedrich, R. %A Limami, A. M. %A Rentsch, D. %A Seo, M. %A Tsay, Y. F. %A Zhang, M. %A Coruzzi, G. %A Lacombe, B. %D 2014 %J Trends Plant Sci %N 1 %P 5-9 %R 10.1016/j.tplants.2013.08.008 %T A unified nomenclature of NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER family members in plants %U http://www.ncbi.nlm.nih.gov/pubmed/24055139 %V 19 %X Members of the plant NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER (NRT1/PTR) family display protein sequence homology with the SLC15/PepT/PTR/POT family of peptide transporters in animals. In comparison to their animal and bacterial counterparts, these plant proteins transport a wide variety of substrates: nitrate, peptides, amino acids, dicarboxylates, glucosinolates, IAA, and ABA. The phylogenetic relationship of the members of the NRT1/PTR family in 31 fully sequenced plant genomes allowed the identification of unambiguous clades, defining eight subfamilies. The phylogenetic tree was used to determine a unified nomenclature of this family named NPF, for NRT1/PTR FAMILY. We propose that the members should be named accordingly: NPFX.Y, where X denotes the subfamily and Y the individual member within the species.
• Maierhofer, T., Lind, C., Hüttl, S., Scherzer, S., Papenfuß, M., Simon, J., Al-Rasheid, K.A., Ache, P., Rennenberg, H., Hedrich, R., Müller, T.D., und Geiger, D. (2014) „A Single-Pore Residue Renders the Arabidopsis Root Anion Channel SLAH2 Highly Nitrate Selective“, Plant Cell, 26(6), 2554–2567, verfügbar unter: https://doi.org/10.1105/tpc.114.125849.
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  In contrast to animal cells, plants use nitrate as a major source of nitrogen. Following the uptake of nitrate, this major macronutrient is fed into the vasculature for long-distance transport. The Arabidopsis thaliana shoot expresses the anion channel SLOW ANION CHANNEL1 (SLAC1) and its homolog SLAC1 HOMOLOGOUS3 (SLAH3), which prefer nitrate as substrate but cannot exclude chloride ions. By contrast, we identified SLAH2 as a nitrate-specific channel that is impermeable for chloride. To understand the molecular basis for nitrate selection in the SLAH2 channel, SLAC1 and SLAH2 were modeled to the structure of HiTehA, a distantly related bacterial member. Structure-guided site-directed mutations converted SLAC1 into a SLAH2-like nitrate-specific anion channel and vice versa. Our findings indicate that two pore-occluding phenylalanines constrict the pore. The selectivity filter of SLAC/SLAH anion channels is determined by the polarity of pore-lining residues located on alpha helix 3. Changing the polar character of a single amino acid side chain (Ser-228) to a nonpolar residue turned the nitrate-selective SLAH2 into a chloride/nitrate-permeable anion channel. Thus, the molecular basis of the anion specificity of SLAC/SLAH anion channels seems to be determined by the presence and constellation of polar side chains that act in concert with the two pore-occluding phenylalanines.

  @article{RN182, abstract = {In contrast to animal cells, plants use nitrate as a major source of nitrogen. Following the uptake of nitrate, this major macronutrient is fed into the vasculature for long-distance transport. The Arabidopsis thaliana shoot expresses the anion channel SLOW ANION CHANNEL1 (SLAC1) and its homolog SLAC1 HOMOLOGOUS3 (SLAH3), which prefer nitrate as substrate but cannot exclude chloride ions. By contrast, we identified SLAH2 as a nitrate-specific channel that is impermeable for chloride. To understand the molecular basis for nitrate selection in the SLAH2 channel, SLAC1 and SLAH2 were modeled to the structure of HiTehA, a distantly related bacterial member. Structure-guided site-directed mutations converted SLAC1 into a SLAH2-like nitrate-specific anion channel and vice versa. Our findings indicate that two pore-occluding phenylalanines constrict the pore. The selectivity filter of SLAC/SLAH anion channels is determined by the polarity of pore-lining residues located on alpha helix 3. Changing the polar character of a single amino acid side chain (Ser-228) to a nonpolar residue turned the nitrate-selective SLAH2 into a chloride/nitrate-permeable anion channel. Thus, the molecular basis of the anion specificity of SLAC/SLAH anion channels seems to be determined by the presence and constellation of polar side chains that act in concert with the two pore-occluding phenylalanines.}, author = {Maierhofer, T. and Lind, C. and Hüttl, S. and Scherzer, S. and Papenfuß, M. and Simon, J. and Al-Rasheid, K. A. and Ache, P. and Rennenberg, H. and Hedrich, R. and Müller, T. D. and Geiger, D.}, journal = {Plant Cell}, keywords = {myOwn}, number = 6, pages = {2554-2567}, title = {A Single-Pore Residue Renders the Arabidopsis Root Anion Channel SLAH2 Highly Nitrate Selective}, type = {Journal Article}, volume = 26, year = 2014 }

  %0 Journal Article %1 RN182 %A Maierhofer, T. %A Lind, C. %A Hüttl, S. %A Scherzer, S. %A Papenfuß, M. %A Simon, J. %A Al-Rasheid, K. A. %A Ache, P. %A Rennenberg, H. %A Hedrich, R. %A Müller, T. D. %A Geiger, D. %D 2014 %J Plant Cell %N 6 %P 2554-2567 %R 10.1105/tpc.114.125849 %T A Single-Pore Residue Renders the Arabidopsis Root Anion Channel SLAH2 Highly Nitrate Selective %U http://www.ncbi.nlm.nih.gov/pubmed/24938289 %V 26 %X In contrast to animal cells, plants use nitrate as a major source of nitrogen. Following the uptake of nitrate, this major macronutrient is fed into the vasculature for long-distance transport. The Arabidopsis thaliana shoot expresses the anion channel SLOW ANION CHANNEL1 (SLAC1) and its homolog SLAC1 HOMOLOGOUS3 (SLAH3), which prefer nitrate as substrate but cannot exclude chloride ions. By contrast, we identified SLAH2 as a nitrate-specific channel that is impermeable for chloride. To understand the molecular basis for nitrate selection in the SLAH2 channel, SLAC1 and SLAH2 were modeled to the structure of HiTehA, a distantly related bacterial member. Structure-guided site-directed mutations converted SLAC1 into a SLAH2-like nitrate-specific anion channel and vice versa. Our findings indicate that two pore-occluding phenylalanines constrict the pore. The selectivity filter of SLAC/SLAH anion channels is determined by the polarity of pore-lining residues located on alpha helix 3. Changing the polar character of a single amino acid side chain (Ser-228) to a nonpolar residue turned the nitrate-selective SLAH2 into a chloride/nitrate-permeable anion channel. Thus, the molecular basis of the anion specificity of SLAC/SLAH anion channels seems to be determined by the presence and constellation of polar side chains that act in concert with the two pore-occluding phenylalanines.
• Gavrin, A., Kaiser, B.N., Geiger, D., Tyerman, S.D., Wen, Z., Bisseling, T., und Fedorova, E.E. (2014) „Adjustment of Host Cells for Accommodation of Symbiotic Bacteria: Vacuole Defunctionalization, HOPS Suppression, and TIP1g Retargeting in Medicago“, The Plant Cell Online, verfügbar unter: https://doi.org/10.1105/tpc.114.128736.
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  In legume–rhizobia symbioses, the bacteria in infected cells are enclosed in a plant membrane, forming organelle-like compartments called symbiosomes. Symbiosomes remain as individual units and avoid fusion with lytic vacuoles of host cells. We observed changes in the vacuole volume of infected cells and thus hypothesized that microsymbionts may cause modifications in vacuole formation or function. To examine this, we quantified the volumes and surface areas of plant cells, vacuoles, and symbiosomes in root nodules of Medicago truncatula and analyzed the expression and localization of VPS11 and VPS39, members of the HOPS vacuole-tethering complex. During the maturation of symbiosomes to become N2-fixing organelles, a developmental switch occurs and changes in vacuole features are induced. For example, we found that expression of VPS11 and VPS39 in infected cells is suppressed and host cell vacuoles contract, permitting the expansion of symbiosomes. Trafficking of tonoplast-targeted proteins in infected symbiotic cells is also altered, as shown by retargeting of the aquaporin TIP1g from the tonoplast membrane to the symbiosome membrane. This retargeting appears to be essential for the maturation of symbiosomes. We propose that these alterations in the function of the vacuole are key events in the adaptation of the plant cell to host intracellular symbiotic bacteria.

  @article{RN180, abstract = {In legume–rhizobia symbioses, the bacteria in infected cells are enclosed in a plant membrane, forming organelle-like compartments called symbiosomes. Symbiosomes remain as individual units and avoid fusion with lytic vacuoles of host cells. We observed changes in the vacuole volume of infected cells and thus hypothesized that microsymbionts may cause modifications in vacuole formation or function. To examine this, we quantified the volumes and surface areas of plant cells, vacuoles, and symbiosomes in root nodules of Medicago truncatula and analyzed the expression and localization of VPS11 and VPS39, members of the HOPS vacuole-tethering complex. During the maturation of symbiosomes to become N2-fixing organelles, a developmental switch occurs and changes in vacuole features are induced. For example, we found that expression of VPS11 and VPS39 in infected cells is suppressed and host cell vacuoles contract, permitting the expansion of symbiosomes. Trafficking of tonoplast-targeted proteins in infected symbiotic cells is also altered, as shown by retargeting of the aquaporin TIP1g from the tonoplast membrane to the symbiosome membrane. This retargeting appears to be essential for the maturation of symbiosomes. We propose that these alterations in the function of the vacuole are key events in the adaptation of the plant cell to host intracellular symbiotic bacteria.}, author = {Gavrin, Aleksandr and Kaiser, Brent N. and Geiger, Dietmar and Tyerman, Stephen D. and Wen, Zhenqyu and Bisseling, Ton and Fedorova, Elena E.}, journal = {The Plant Cell Online}, keywords = {myOwn}, title = {Adjustment of Host Cells for Accommodation of Symbiotic Bacteria: Vacuole Defunctionalization, HOPS Suppression, and TIP1g Retargeting in Medicago}, type = {Journal Article}, year = 2014 }

  %0 Journal Article %1 RN180 %A Gavrin, Aleksandr %A Kaiser, Brent N. %A Geiger, Dietmar %A Tyerman, Stephen D. %A Wen, Zhenqyu %A Bisseling, Ton %A Fedorova, Elena E. %D 2014 %J The Plant Cell Online %R 10.1105/tpc.114.128736 %T Adjustment of Host Cells for Accommodation of Symbiotic Bacteria: Vacuole Defunctionalization, HOPS Suppression, and TIP1g Retargeting in Medicago %U http://www.plantcell.org/content/early/2014/09/09/tpc.114.128736.abstract %X In legume–rhizobia symbioses, the bacteria in infected cells are enclosed in a plant membrane, forming organelle-like compartments called symbiosomes. Symbiosomes remain as individual units and avoid fusion with lytic vacuoles of host cells. We observed changes in the vacuole volume of infected cells and thus hypothesized that microsymbionts may cause modifications in vacuole formation or function. To examine this, we quantified the volumes and surface areas of plant cells, vacuoles, and symbiosomes in root nodules of Medicago truncatula and analyzed the expression and localization of VPS11 and VPS39, members of the HOPS vacuole-tethering complex. During the maturation of symbiosomes to become N2-fixing organelles, a developmental switch occurs and changes in vacuole features are induced. For example, we found that expression of VPS11 and VPS39 in infected cells is suppressed and host cell vacuoles contract, permitting the expansion of symbiosomes. Trafficking of tonoplast-targeted proteins in infected symbiotic cells is also altered, as shown by retargeting of the aquaporin TIP1g from the tonoplast membrane to the symbiosome membrane. This retargeting appears to be essential for the maturation of symbiosomes. We propose that these alterations in the function of the vacuole are key events in the adaptation of the plant cell to host intracellular symbiotic bacteria.

• Imes, D., Mumm, P., Böhm, J., Al-Rasheid, K., Marten, I., Geiger, D., und Hedrich, R. (2013) „Open stomata 1 (OST1) kinase controls R-type anion channel QUAC1 in Arabidopsis guard cells“, Plant Journal, 74(3), 372–382, verfügbar unter: https://doi.org/10.1111/tpj.12133.
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  @article{RN179, author = {Imes, D. and Mumm, P. and Böhm, J. and Al-Rasheid, K.A.S. and Marten, I. and Geiger, D. and Hedrich, R.}, journal = {Plant Journal}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2013,title = {Open stomata 1 (OST1) kinase controls R-type anion channel QUAC1 in Arabidopsis guard cells},journal = {Plant Journal},year = {2013},volume = {74},number = {3},pages = {372-382},author = {Imes, D. and Mumm, P. and Böhm, J. and Al-Rasheid, K.A.S. and Marten, I. and Geiger, D. and Hedrich, R.}}]}, number = 3, pages = {372-382}, title = {Open stomata 1 (OST1) kinase controls R-type anion channel QUAC1 in Arabidopsis guard cells}, type = {Journal Article}, volume = 74, year = 2013 }

  %0 Journal Article %1 RN179 %A Imes, D. %A Mumm, P. %A Böhm, J. %A Al-Rasheid, K.A.S. %A Marten, I. %A Geiger, D. %A Hedrich, R. %D 2013 %J Plant Journal %N 3 %P 372-382 %R 10.1111/tpj.12133 %T Open stomata 1 (OST1) kinase controls R-type anion channel QUAC1 in Arabidopsis guard cells %U http://www.scopus.com/inward/record.url?eid=2-s2.0-84876677899&partnerID=MN8TOARS %V 74
• Derrer, C., Wittek, A., Bamberg, E., Carpaneto, A., Dreyer, I., und Geiger, D. (2013) „Conformational changes represent the rate-limiting step in the transport cycle of maize sucrose transporter1“, Plant Cell, 25(8), 3010–3021, verfügbar unter: https://doi.org/10.1105/tpc.113.113621.
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  @article{RN175, author = {Derrer, C. and Wittek, A. and Bamberg, E. and Carpaneto, A. and Dreyer, I. and Geiger, D.}, journal = {Plant Cell}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2013,title = {Conformational changes represent the rate-limiting step in the transport cycle of maize sucrose transporter1},journal = {Plant Cell},year = {2013},volume = {25},number = {8},pages = {3010-3021},author = {Derrer, C. and Wittek, A. and Bamberg, E. and Carpaneto, A. and Dreyer, I. and Geiger, D.}}]}, number = 8, pages = {3010-3021}, title = {Conformational changes represent the rate-limiting step in the transport cycle of maize sucrose transporter1}, type = {Journal Article}, volume = 25, year = 2013 }

  %0 Journal Article %1 RN175 %A Derrer, C. %A Wittek, A. %A Bamberg, E. %A Carpaneto, A. %A Dreyer, I. %A Geiger, D. %D 2013 %J Plant Cell %N 8 %P 3010-3021 %R 10.1105/tpc.113.113621 %T Conformational changes represent the rate-limiting step in the transport cycle of maize sucrose transporter1 %U http://www.scopus.com/inward/record.url?eid=2-s2.0-84884686545&partnerID=MN8TOARS %V 25
• Demir, F., Horntrich, C., Blachutzik, J., Scherzer, S., Reinders, Y., Kierszniowska, S., Schulze, W., Harms, G., Hedrich, R., Geiger, D., und Kreuzer, I. (2013) „Arabidopsis nanodomain-delimited ABA signaling pathway regulates the anion channel SLAH3“, Proceedings of the National Academy of Sciences of the United States of America, 110(20), 8296–8301, verfügbar unter: https://doi.org/10.1073/pnas.1211667110.
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  @article{RN161, author = {Demir, F. and Horntrich, C. and Blachutzik, J.O. and Scherzer, S. and Reinders, Y. and Kierszniowska, S. and Schulze, W.X. and Harms, G.S. and Hedrich, R. and Geiger, D. and Kreuzer, I.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2013,title = {Arabidopsis nanodomain-delimited ABA signaling pathway regulates the anion channel SLAH3},journal = {Proceedings of the National Academy of Sciences of the United States of America},year = {2013},volume = {110},number = {20},pages = {8296-8301},author = {Demir, F. and Horntrich, C. and Blachutzik, J.O. and Scherzer, S. and Reinders, Y. and Kierszniowska, S. and Schulze, W.X. and Harms, G.S. and Hedrich, R. and Geiger, D. and Kreuzer, I.}}]}, number = 20, pages = {8296-8301}, title = {Arabidopsis nanodomain-delimited ABA signaling pathway regulates the anion channel SLAH3}, type = {Journal Article}, volume = 110, year = 2013 }

  %0 Journal Article %1 RN161 %A Demir, F. %A Horntrich, C. %A Blachutzik, J.O. %A Scherzer, S. %A Reinders, Y. %A Kierszniowska, S. %A Schulze, W.X. %A Harms, G.S. %A Hedrich, R. %A Geiger, D. %A Kreuzer, I. %D 2013 %J Proceedings of the National Academy of Sciences of the United States of America %N 20 %P 8296-8301 %R 10.1073/pnas.1211667110 %T Arabidopsis nanodomain-delimited ABA signaling pathway regulates the anion channel SLAH3 %U http://www.scopus.com/inward/record.url?eid=2-s2.0-84877860081&partnerID=MN8TOARS %V 110
• Mumm, P., Imes, D., Martinoia, E., Al-Rasheid, K.A., Geiger, D., Marten, I., und Hedrich, R. (2013) „C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1“, Mol Plant, 6(5), 1550–63, verfügbar unter: https://doi.org/10.1093/mp/sst008.
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  Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al(3+)-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al(3+)-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activation–deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.

  @article{RN184, abstract = {Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al(3+)-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al(3+)-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activation–deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.}, author = {Mumm, P. and Imes, D. and Martinoia, E. and Al-Rasheid, K. A. and Geiger, D. and Marten, I. and Hedrich, R.}, journal = {Mol Plant}, keywords = {myOwn}, number = 5, pages = {1550-63}, title = {C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1}, type = {Journal Article}, volume = 6, year = 2013 }

  %0 Journal Article %1 RN184 %A Mumm, P. %A Imes, D. %A Martinoia, E. %A Al-Rasheid, K. A. %A Geiger, D. %A Marten, I. %A Hedrich, R. %D 2013 %J Mol Plant %N 5 %P 1550-63 %R 10.1093/mp/sst008 %T C-terminus-mediated voltage gating of Arabidopsis guard cell anion channel QUAC1 %U http://www.ncbi.nlm.nih.gov/pubmed/23314055 %V 6 %X Anion transporters in plants play a fundamental role in volume regulation and signaling. Currently, two plasma membrane-located anion channel families—SLAC/SLAH and ALMT—are known. Among the ALMT family, the root-expressed ALuminium-activated Malate Transporter 1 was identified by comparison of aluminum-tolerant and Al(3+)-sensitive wheat cultivars and was subsequently shown to mediate voltage-independent malate currents. In contrast, ALMT12/QUAC1 (QUickly activating Anion Channel1) is expressed in guard cells transporting malate in an Al(3+)-insensitive and highly voltage-dependent manner. So far, no information is available about the structure and mechanism of voltage-dependent gating with the QUAC1 channel protein. Here, we analyzed gating of QUAC1-type currents in the plasma membrane of guard cells and QUAC1-expressing oocytes revealing similar voltage dependencies and activation–deactivation kinetics. In the heterologous expression system, QUAC1 was electrophysiologically characterized at increasing extra- and intracellular malate concentrations. Thereby, malate additively stimulated the voltage-dependent QUAC1 activity. In search of structural determinants of the gating process, we could not identify transmembrane domains common for voltage-sensitive channels. However, site-directed mutations and deletions at the C-terminus of QUAC1 resulted in altered voltage-dependent channel activity. Interestingly, the replacement of a single glutamate residue, which is conserved in ALMT channels from different clades, by an alanine disrupted QUAC1 activity. Together with C- and N-terminal tagging, these results indicate that the cytosolic C-terminus is involved in the voltage-dependent gating mechanism of QUAC1.

• Egenberger, B., Gorboulev, V., Keller, T., Gorbunov, D., Gottlieb, N., Geiger, D., Mueller, T., und Koepsell, H. (2012) „A substrate binding hinge domain is critical for transport-related structural changes of organic cation transporter 1“, Journal of Biological Chemistry, 287(37), 31561–31573, verfügbar unter: https://doi.org/10.1074/jbc.M112.388793.
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  @article{RN169, author = {Egenberger, B. and Gorboulev, V. and Keller, T. and Gorbunov, D. and Gottlieb, N. and Geiger, D. and Mueller, T.D. and Koepsell, H.}, journal = {Journal of Biological Chemistry}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2012,title = {A substrate binding hinge domain is critical for transport-related structural changes of organic cation transporter 1},journal = {Journal of Biological Chemistry},year = {2012},volume = {287},number = {37},pages = {31561-31573},author = {Egenberger, B. and Gorboulev, V. and Keller, T. and Gorbunov, D. and Gottlieb, N. and Geiger, D. and Mueller, T.D. and Koepsell, H.}}]}, number = 37, pages = {31561-31573}, title = {A substrate binding hinge domain is critical for transport-related structural changes of organic cation transporter 1}, type = {Journal Article}, volume = 287, year = 2012 }

  %0 Journal Article %1 RN169 %A Egenberger, B. %A Gorboulev, V. %A Keller, T. %A Gorbunov, D. %A Gottlieb, N. %A Geiger, D. %A Mueller, T.D. %A Koepsell, H. %D 2012 %J Journal of Biological Chemistry %N 37 %P 31561-31573 %R 10.1074/jbc.M112.388793 %T A substrate binding hinge domain is critical for transport-related structural changes of organic cation transporter 1 %U http://www.scopus.com/inward/record.url?eid=2-s2.0-84866133123&partnerID=MN8TOARS %V 287
• Dreyer, I., Gomez-Porras, J.L., Riaño-Pachón, D.M., Hedrich, R., und Geiger, D. (2012) „Molecular Evolution of Slow and Quick Anion Channels (SLACs and QUACs/ALMTs)“, Front Plant Sci, 3, 263, verfügbar unter: https://doi.org/10.3389/fpls.2012.00263.
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  Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant) SLAC-like and 422 (402 non-redundant) ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.

  @article{RN185, abstract = {Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant) SLAC-like and 422 (402 non-redundant) ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.}, author = {Dreyer, I. and Gomez-Porras, J. L. and Riaño-Pachón, D. M. and Hedrich, R. and Geiger, D.}, journal = {Front Plant Sci}, keywords = {myOwn}, pages = 263, title = {Molecular Evolution of Slow and Quick Anion Channels (SLACs and QUACs/ALMTs)}, type = {Journal Article}, volume = 3, year = 2012 }

  %0 Journal Article %1 RN185 %A Dreyer, I. %A Gomez-Porras, J. L. %A Riaño-Pachón, D. M. %A Hedrich, R. %A Geiger, D. %D 2012 %J Front Plant Sci %P 263 %R 10.3389/fpls.2012.00263 %T Molecular Evolution of Slow and Quick Anion Channels (SLACs and QUACs/ALMTs) %U http://www.ncbi.nlm.nih.gov/pubmed/23226151 %V 3 %X Electrophysiological analyses conducted about 25 years ago detected two types of anion channels in the plasma membrane of guard cells. One type of channel responds slowly to changes in membrane voltage while the other responds quickly. Consequently, they were named SLAC, for SLow Anion Channel, and QUAC, for QUick Anion Channel. Recently, genes SLAC1 and QUAC1/ALMT12, underlying the two different anion current components, could be identified in the model plant Arabidopsis thaliana. Expression of the gene products in Xenopus oocytes confirmed the quick and slow current kinetics. In this study we provide an overview on our current knowledge on slow and quick anion channels in plants and analyze the molecular evolution of ALMT/QUAC-like and SLAC-like channels. We discovered fingerprints that allow screening databases for these channel types and were able to identify 192 (177 non-redundant) SLAC-like and 422 (402 non-redundant) ALMT/QUAC-like proteins in the fully sequenced genomes of 32 plant species. Phylogenetic analyses provided new insights into the molecular evolution of these channel types. We also combined sequence alignment and clustering with predictions of protein features, leading to the identification of known conserved phosphorylation sites in SLAC1-like channels along with potential sites that have not been yet experimentally confirmed. Using a similar strategy to analyze the hydropathicity of ALMT/QUAC-like channels, we propose a modified topology with additional transmembrane regions that integrates structure and function of these membrane proteins. Our results suggest that cross-referencing phylogenetic analyses with position-specific protein properties and functional data could be a very powerful tool for genome research approaches in general.
• Scherzer, S., Maierhofer, T., Al-Rasheid, K.A., Geiger, D., und Hedrich, R. (2012) „Multiple calcium-dependent kinases modulate ABA-activated guard cell anion channels“, Mol Plant, 5(6), 1409–12, verfügbar unter: https://doi.org/10.1093/mp/sss084.
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  @article{RN186, author = {Scherzer, S. and Maierhofer, T. and Al-Rasheid, K. A. and Geiger, D. and Hedrich, R.}, journal = {Mol Plant}, keywords = {myOwn}, number = 6, pages = {1409-12}, title = {Multiple calcium-dependent kinases modulate ABA-activated guard cell anion channels}, type = {Journal Article}, volume = 5, year = 2012 }

  %0 Journal Article %1 RN186 %A Scherzer, S. %A Maierhofer, T. %A Al-Rasheid, K. A. %A Geiger, D. %A Hedrich, R. %D 2012 %J Mol Plant %N 6 %P 1409-12 %R 10.1093/mp/sss084 %T Multiple calcium-dependent kinases modulate ABA-activated guard cell anion channels %U http://www.ncbi.nlm.nih.gov/pubmed/22933711 %V 5
• Nour-Eldin, H., Andersen, T., Burow, M., Madsen, S., Jørgensen, M., Olsen, C., Dreyer, I., Hedrich, R., Geiger, D., und Halkier, B. (2012) „NRT/PTR transporters are essential for translocation of glucosinolate defence compounds to seeds“, Nature, 488(7412), 531–534, verfügbar unter: https://doi.org/10.1038/nature11285.
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  @article{RN172, author = {Nour-Eldin, H.H. and Andersen, T.G. and Burow, M. and Madsen, S.R. and Jørgensen, M.E. and Olsen, C.E. and Dreyer, I. and Hedrich, R. and Geiger, D. and Halkier, B.A.}, journal = {Nature}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2012,title = {NRT/PTR transporters are essential for translocation of glucosinolate defence compounds to seeds},journal = {Nature},year = {2012},volume = {488},number = {7412},pages = {531-534},author = {Nour-Eldin, H.H. and Andersen, T.G. and Burow, M. and Madsen, S.R. and Jørgensen, M.E. and Olsen, C.E. and Dreyer, I. and Hedrich, R. and Geiger, D. and Halkier, B.A.}}]}, number = 7412, pages = {531-534}, title = {NRT/PTR transporters are essential for translocation of glucosinolate defence compounds to seeds}, type = {Journal Article}, volume = 488, year = 2012 }

  %0 Journal Article %1 RN172 %A Nour-Eldin, H.H. %A Andersen, T.G. %A Burow, M. %A Madsen, S.R. %A Jørgensen, M.E. %A Olsen, C.E. %A Dreyer, I. %A Hedrich, R. %A Geiger, D. %A Halkier, B.A. %D 2012 %J Nature %N 7412 %P 531-534 %R 10.1038/nature11285 %T NRT/PTR transporters are essential for translocation of glucosinolate defence compounds to seeds %U http://www.scopus.com/inward/record.url?eid=2-s2.0-84865206069&partnerID=MN8TOARS %V 488
• Roelfsema, M.R., Hedrich, R., und Geiger, D. (2012) „Anion channels: master switches of stress responses“, Trends Plant Sci, 17(4), 221–9, verfügbar unter: https://doi.org/10.1016/j.tplants.2012.01.009.
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  During stress, plant cells activate anion channels and trigger the release of anions across the plasma membrane. Recently, two new gene families have been identified that encode major groups of anion channels. The SLAC/SLAH channels are characterized by slow voltage-dependent activation (S-type), whereas ALMT genes encode rapid-activating channels (R-type). Both S- and R-type channels are stimulated in guard cells by the stress hormone ABA, which leads to stomatal closure. Besides their role in ABA-dependent stomatal movement, anion channels are also activated by biotic stress factors such as microbe-associated molecular patterns (MAMPs). Given that anion channels occur throughout the plant kingdom, they are likely to serve a general function as master switches of stress responses.

  @article{RN187, abstract = {During stress, plant cells activate anion channels and trigger the release of anions across the plasma membrane. Recently, two new gene families have been identified that encode major groups of anion channels. The SLAC/SLAH channels are characterized by slow voltage-dependent activation (S-type), whereas ALMT genes encode rapid-activating channels (R-type). Both S- and R-type channels are stimulated in guard cells by the stress hormone ABA, which leads to stomatal closure. Besides their role in ABA-dependent stomatal movement, anion channels are also activated by biotic stress factors such as microbe-associated molecular patterns (MAMPs). Given that anion channels occur throughout the plant kingdom, they are likely to serve a general function as master switches of stress responses.}, author = {Roelfsema, M. R. and Hedrich, R. and Geiger, D.}, journal = {Trends Plant Sci}, keywords = {myOwn}, number = 4, pages = {221-9}, title = {Anion channels: master switches of stress responses}, type = {Journal Article}, volume = 17, year = 2012 }

  %0 Journal Article %1 RN187 %A Roelfsema, M. R. %A Hedrich, R. %A Geiger, D. %D 2012 %J Trends Plant Sci %N 4 %P 221-9 %R 10.1016/j.tplants.2012.01.009 %T Anion channels: master switches of stress responses %U http://www.ncbi.nlm.nih.gov/pubmed/22381565 %V 17 %X During stress, plant cells activate anion channels and trigger the release of anions across the plasma membrane. Recently, two new gene families have been identified that encode major groups of anion channels. The SLAC/SLAH channels are characterized by slow voltage-dependent activation (S-type), whereas ALMT genes encode rapid-activating channels (R-type). Both S- and R-type channels are stimulated in guard cells by the stress hormone ABA, which leads to stomatal closure. Besides their role in ABA-dependent stomatal movement, anion channels are also activated by biotic stress factors such as microbe-associated molecular patterns (MAMPs). Given that anion channels occur throughout the plant kingdom, they are likely to serve a general function as master switches of stress responses.

• Wingenter, K., Trentmann, O., Winschuh, I., Hörmiller, I., Heyer, A., Reinders, J., Schulz, A., Geiger, D., Hedrich, R., und Neuhaus, H. (2011) „A member of the mitogen-activated protein 3-kinase family is involved in the regulation of plant vacuolar glucose uptake“, Plant Journal, 68(5), 890–900, verfügbar unter: https://doi.org/10.1111/j.1365-313X.2011.04739.x.
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  @article{RN177, author = {Wingenter, K. and Trentmann, O. and Winschuh, I. and Hörmiller, I.I. and Heyer, A.G. and Reinders, J. and Schulz, A. and Geiger, D. and Hedrich, R. and Neuhaus, H.E.}, journal = {Plant Journal}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2011,title = {A member of the mitogen-activated protein 3-kinase family is involved in the regulation of plant vacuolar glucose uptake},journal = {Plant Journal},year = {2011},volume = {68},number = {5},pages = {890-900},author = {Wingenter, K. and Trentmann, O. and Winschuh, I. and Hörmiller, I.I. and Heyer, A.G. and Reinders, J. and Schulz, A. and Geiger, D. and Hedrich, R. and Neuhaus, H.E.}}]}, number = 5, pages = {890-900}, title = {A member of the mitogen-activated protein 3-kinase family is involved in the regulation of plant vacuolar glucose uptake}, type = {Journal Article}, volume = 68, year = 2011 }

  %0 Journal Article %1 RN177 %A Wingenter, K. %A Trentmann, O. %A Winschuh, I. %A Hörmiller, I.I. %A Heyer, A.G. %A Reinders, J. %A Schulz, A. %A Geiger, D. %A Hedrich, R. %A Neuhaus, H.E. %D 2011 %J Plant Journal %N 5 %P 890-900 %R 10.1111/j.1365-313X.2011.04739.x %T A member of the mitogen-activated protein 3-kinase family is involved in the regulation of plant vacuolar glucose uptake %U http://www.scopus.com/inward/record.url?eid=2-s2.0-82355169008&partnerID=MN8TOARS %V 68
• Geiger, D., Maierhofer, T., Al-Rasheid, K.A., Scherzer, S., Mumm, P., Liese, A., Ache, P., Wellmann, C., Marten, I., Grill, E., Romeis, T., und Hedrich, R. (2011) „Stomatal closure by fast abscisic acid signaling is mediated by the guard cell anion channel SLAH3 and the receptor RCAR1“, Sci Signal, 4(173), ra32, verfügbar unter: https://doi.org/10.1126/scisignal.2001346.
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  S-type anion channels are direct targets of abscisic acid (ABA) signaling and contribute to chloride and nitrate release from guard cells, which in turn initiates stomatal closure. SLAC1 was the first component of the guard cell S-type anion channel identified. However, we found that guard cells of Arabidopsis SLAC1 mutants exhibited nitrate conductance. SLAH3 (SLAC1 homolog 3) was also present in guard cells, and coexpression of SLAH3 with the calcium ion (Ca2+)-dependent kinase CPK21 in Xenopus oocytes mediated nitrate-induced anion currents. Nitrate, calcium, and phosphorylation regulated SLAH3 activity. CPK21-dependent SLAH3 phosphorylation and activation were blocked by ABI1, a PP2C-type protein phosphatase that is inhibited by ABA and inhibits the ABA signaling pathway in guard cells. We reconstituted the ABA-stimulated phosphorylation of the SLAH3 amino-terminal domain by CPK21 in vitro by including the ABA receptor-phosphatase complex RCAR1-ABI1 in the reactions. We propose that ABA perception by the complex consisting of ABA receptors of the RCAR/PYR/PYL family and ABI1 releases CPK21 from inhibition by ABI1, and then CPK21 is further activated by an increase in the cytosolic Ca2+ concentration, leading to its phosphorylation of SLAH3. Thus, the identification of SLAH3 as the nitrate-, calcium-, and ABA-sensitive guard cell anion channel provides insights into the relationship among stomatal response to drought, signaling by nitrate, and nitrate metabolism.

  @article{RN189, abstract = {S-type anion channels are direct targets of abscisic acid (ABA) signaling and contribute to chloride and nitrate release from guard cells, which in turn initiates stomatal closure. SLAC1 was the first component of the guard cell S-type anion channel identified. However, we found that guard cells of Arabidopsis SLAC1 mutants exhibited nitrate conductance. SLAH3 (SLAC1 homolog 3) was also present in guard cells, and coexpression of SLAH3 with the calcium ion (Ca2+)-dependent kinase CPK21 in Xenopus oocytes mediated nitrate-induced anion currents. Nitrate, calcium, and phosphorylation regulated SLAH3 activity. CPK21-dependent SLAH3 phosphorylation and activation were blocked by ABI1, a PP2C-type protein phosphatase that is inhibited by ABA and inhibits the ABA signaling pathway in guard cells. We reconstituted the ABA-stimulated phosphorylation of the SLAH3 amino-terminal domain by CPK21 in vitro by including the ABA receptor-phosphatase complex RCAR1-ABI1 in the reactions. We propose that ABA perception by the complex consisting of ABA receptors of the RCAR/PYR/PYL family and ABI1 releases CPK21 from inhibition by ABI1, and then CPK21 is further activated by an increase in the cytosolic Ca2+ concentration, leading to its phosphorylation of SLAH3. Thus, the identification of SLAH3 as the nitrate-, calcium-, and ABA-sensitive guard cell anion channel provides insights into the relationship among stomatal response to drought, signaling by nitrate, and nitrate metabolism.}, author = {Geiger, D. and Maierhofer, T. and Al-Rasheid, K. A. and Scherzer, S. and Mumm, P. and Liese, A. and Ache, P. and Wellmann, C. and Marten, I. and Grill, E. and Romeis, T. and Hedrich, R.}, journal = {Sci Signal}, keywords = {myOwn}, number = 173, pages = {ra32}, title = {Stomatal closure by fast abscisic acid signaling is mediated by the guard cell anion channel SLAH3 and the receptor RCAR1}, type = {Journal Article}, volume = 4, year = 2011 }

  %0 Journal Article %1 RN189 %A Geiger, D. %A Maierhofer, T. %A Al-Rasheid, K. A. %A Scherzer, S. %A Mumm, P. %A Liese, A. %A Ache, P. %A Wellmann, C. %A Marten, I. %A Grill, E. %A Romeis, T. %A Hedrich, R. %D 2011 %J Sci Signal %N 173 %P ra32 %R 10.1126/scisignal.2001346 %T Stomatal closure by fast abscisic acid signaling is mediated by the guard cell anion channel SLAH3 and the receptor RCAR1 %U http://www.ncbi.nlm.nih.gov/pubmed/21586729 %V 4 %X S-type anion channels are direct targets of abscisic acid (ABA) signaling and contribute to chloride and nitrate release from guard cells, which in turn initiates stomatal closure. SLAC1 was the first component of the guard cell S-type anion channel identified. However, we found that guard cells of Arabidopsis SLAC1 mutants exhibited nitrate conductance. SLAH3 (SLAC1 homolog 3) was also present in guard cells, and coexpression of SLAH3 with the calcium ion (Ca2+)-dependent kinase CPK21 in Xenopus oocytes mediated nitrate-induced anion currents. Nitrate, calcium, and phosphorylation regulated SLAH3 activity. CPK21-dependent SLAH3 phosphorylation and activation were blocked by ABI1, a PP2C-type protein phosphatase that is inhibited by ABA and inhibits the ABA signaling pathway in guard cells. We reconstituted the ABA-stimulated phosphorylation of the SLAH3 amino-terminal domain by CPK21 in vitro by including the ABA receptor-phosphatase complex RCAR1-ABI1 in the reactions. We propose that ABA perception by the complex consisting of ABA receptors of the RCAR/PYR/PYL family and ABI1 releases CPK21 from inhibition by ABI1, and then CPK21 is further activated by an increase in the cytosolic Ca2+ concentration, leading to its phosphorylation of SLAH3. Thus, the identification of SLAH3 as the nitrate-, calcium-, and ABA-sensitive guard cell anion channel provides insights into the relationship among stomatal response to drought, signaling by nitrate, and nitrate metabolism.
• Escalante-Pérez, M., Krol, E., Stange, A., Geiger, D., Al-Rasheid, K.A., Hause, B., Neher, E., und Hedrich, R. (2011) „A special pair of phytohormones controls excitability, slow closure, and external stomach formation in the Venus flytrap“, Proc Natl Acad Sci U S A, 108(37), 15492–7, verfügbar unter: https://doi.org/10.1073/pnas.1112535108.
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  Venus flytrap's leaves can catch an insect in a fraction of a second. Since the time of Charles Darwin, scientists have struggled to understand the sensory biology and biomechanics of this plant, Dionaea muscipula. Here we show that insect-capture of Dionaea traps is modulated by the phytohormone abscisic acid (ABA) and jasmonates. Water-stressed Dionaea, as well as those exposed to the drought-stress hormone ABA, are less sensitive to mechanical stimulation. In contrast, application of 12-oxo-phytodienoic acid (OPDA), a precursor of the phytohormone jasmonic acid (JA), the methyl ester of JA (Me-JA), and coronatine (COR), the molecular mimic of the isoleucine conjugate of JA (JA-Ile), triggers secretion of digestive enzymes without any preceding mechanical stimulus. Such secretion is accompanied by slow trap closure. Under physiological conditions, insect-capture is associated with Ca(2+) signaling and a rise in OPDA, Apparently, jasmonates bypass hapto-electric processes associated with trap closure. However, ABA does not affect OPDA-dependent gland activity. Therefore, signals for trap movement and secretion seem to involve separate pathways. Jasmonates are systemically active because application to a single trap induces secretion and slow closure not only in the given trap but also in all others. Furthermore, formerly touch-insensitive trap sectors are converted into mechanosensitive ones. These findings demonstrate that prey-catching Dionaea combines plant-specific signaling pathways, involving OPDA and ABA with a rapidly acting trigger, which uses ion channels, action potentials, and Ca(2+) signals.

  @article{RN188, abstract = {Venus flytrap's leaves can catch an insect in a fraction of a second. Since the time of Charles Darwin, scientists have struggled to understand the sensory biology and biomechanics of this plant, Dionaea muscipula. Here we show that insect-capture of Dionaea traps is modulated by the phytohormone abscisic acid (ABA) and jasmonates. Water-stressed Dionaea, as well as those exposed to the drought-stress hormone ABA, are less sensitive to mechanical stimulation. In contrast, application of 12-oxo-phytodienoic acid (OPDA), a precursor of the phytohormone jasmonic acid (JA), the methyl ester of JA (Me-JA), and coronatine (COR), the molecular mimic of the isoleucine conjugate of JA (JA-Ile), triggers secretion of digestive enzymes without any preceding mechanical stimulus. Such secretion is accompanied by slow trap closure. Under physiological conditions, insect-capture is associated with Ca(2+) signaling and a rise in OPDA, Apparently, jasmonates bypass hapto-electric processes associated with trap closure. However, ABA does not affect OPDA-dependent gland activity. Therefore, signals for trap movement and secretion seem to involve separate pathways. Jasmonates are systemically active because application to a single trap induces secretion and slow closure not only in the given trap but also in all others. Furthermore, formerly touch-insensitive trap sectors are converted into mechanosensitive ones. These findings demonstrate that prey-catching Dionaea combines plant-specific signaling pathways, involving OPDA and ABA with a rapidly acting trigger, which uses ion channels, action potentials, and Ca(2+) signals.}, author = {Escalante-Pérez, M. and Krol, E. and Stange, A. and Geiger, D. and Al-Rasheid, K. A. and Hause, B. and Neher, E. and Hedrich, R.}, journal = {Proc Natl Acad Sci U S A}, keywords = {myOwn}, number = 37, pages = {15492-7}, title = {A special pair of phytohormones controls excitability, slow closure, and external stomach formation in the Venus flytrap}, type = {Journal Article}, volume = 108, year = 2011 }

  %0 Journal Article %1 RN188 %A Escalante-Pérez, M. %A Krol, E. %A Stange, A. %A Geiger, D. %A Al-Rasheid, K. A. %A Hause, B. %A Neher, E. %A Hedrich, R. %D 2011 %J Proc Natl Acad Sci U S A %N 37 %P 15492-7 %R 10.1073/pnas.1112535108 %T A special pair of phytohormones controls excitability, slow closure, and external stomach formation in the Venus flytrap %U http://www.ncbi.nlm.nih.gov/pubmed/21896747 %V 108 %X Venus flytrap's leaves can catch an insect in a fraction of a second. Since the time of Charles Darwin, scientists have struggled to understand the sensory biology and biomechanics of this plant, Dionaea muscipula. Here we show that insect-capture of Dionaea traps is modulated by the phytohormone abscisic acid (ABA) and jasmonates. Water-stressed Dionaea, as well as those exposed to the drought-stress hormone ABA, are less sensitive to mechanical stimulation. In contrast, application of 12-oxo-phytodienoic acid (OPDA), a precursor of the phytohormone jasmonic acid (JA), the methyl ester of JA (Me-JA), and coronatine (COR), the molecular mimic of the isoleucine conjugate of JA (JA-Ile), triggers secretion of digestive enzymes without any preceding mechanical stimulus. Such secretion is accompanied by slow trap closure. Under physiological conditions, insect-capture is associated with Ca(2+) signaling and a rise in OPDA, Apparently, jasmonates bypass hapto-electric processes associated with trap closure. However, ABA does not affect OPDA-dependent gland activity. Therefore, signals for trap movement and secretion seem to involve separate pathways. Jasmonates are systemically active because application to a single trap induces secretion and slow closure not only in the given trap but also in all others. Furthermore, formerly touch-insensitive trap sectors are converted into mechanosensitive ones. These findings demonstrate that prey-catching Dionaea combines plant-specific signaling pathways, involving OPDA and ABA with a rapidly acting trigger, which uses ion channels, action potentials, and Ca(2+) signals.
• Geiger, D. (2011) „Plant sucrose transporters from a biophysical point of view“, Molecular Plant, 4(3), 395–406, verfügbar unter: https://doi.org/10.1093/mp/ssr029.
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  @article{RN173, author = {Geiger, D.}, journal = {Molecular Plant}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2011,title = {Plant sucrose transporters from a biophysical point of view},journal = {Molecular Plant},year = {2011},volume = {4},number = {3},pages = {395-406},author = {Geiger, D.}}]}, number = 3, pages = {395-406}, title = {Plant sucrose transporters from a biophysical point of view}, type = {Journal Article}, volume = 4, year = 2011 }

  %0 Journal Article %1 RN173 %A Geiger, D. %D 2011 %J Molecular Plant %N 3 %P 395-406 %R 10.1093/mp/ssr029 %T Plant sucrose transporters from a biophysical point of view %U http://www.scopus.com/inward/record.url?eid=2-s2.0-79957528276&partnerID=MN8TOARS %V 4

• Amien, S., Kliwer, I., Márton, M., Debener, T., Geiger, D., Becker, D., und Dresselhaus, T. (2010) „Defensin-like ZmES4 mediates pollen tube burst in maize via opening of the potassium channel KZM1“, PLoS Biology, 8(6), verfügbar unter: https://doi.org/10.1371/journal.pbio.1000388.
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  @article{RN174, author = {Amien, S. and Kliwer, I. and Márton, M.L. and Debener, T. and Geiger, D. and Becker, D. and Dresselhaus, T.}, journal = {PLoS Biology}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2010,title = {Defensin-like ZmES4 mediates pollen tube burst in maize via opening of the potassium channel KZM1},journal = {PLoS Biology},year = {2010},volume = {8},number = {6},author = {Amien, S. and Kliwer, I. and Márton, M.L. and Debener, T. and Geiger, D. and Becker, D. and Dresselhaus, T.}}]}, number = 6, title = {Defensin-like ZmES4 mediates pollen tube burst in maize via opening of the potassium channel KZM1}, type = {Journal Article}, volume = 8, year = 2010 }

  %0 Journal Article %1 RN174 %A Amien, S. %A Kliwer, I. %A Márton, M.L. %A Debener, T. %A Geiger, D. %A Becker, D. %A Dresselhaus, T. %D 2010 %J PLoS Biology %N 6 %R 10.1371/journal.pbio.1000388 %T Defensin-like ZmES4 mediates pollen tube burst in maize via opening of the potassium channel KZM1 %U http://www.scopus.com/inward/record.url?eid=2-s2.0-77954697561&partnerID=MN8TOARS %V 8
• Meyer, S., Mumm, P., Imes, D., Endler, A., Weder, B., Al-Rasheid, K.A., Geiger, D., Marten, I., Martinoia, E., und Hedrich, R. (2010) „AtALMT12 represents an R-type anion channel required for stomatal movement in Arabidopsis guard cells“, Plant J, 63(6), 1054–62, verfügbar unter: https://doi.org/10.1111/j.1365-313X.2010.04302.x.
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  Stomatal pores formed by a pair of guard cells in the leaf epidermis control gas exchange and transpirational water loss. Stomatal closure is mediated by the release of potassium and anions from guard cells. Anion efflux from guard cells involves slow (S-type) and rapid (R-type) anion channels. Recently the SLAC1 gene has been shown to encode the slow, voltage-independent anion channel component in guard cells. In contrast, the R-type channel still awaits identification. Here, we show that AtALMT12, a member of the aluminum activated malate transporter family in Arabidopsis, represents a guard cell R-type anion channel. AtALMT12 is highly expressed in guard cells and is targeted to the plasma membrane. Plants lacking AtALMT12 are impaired in dark- and CO₂ -induced stomatal closure, as well as in response to the drought-stress hormone abscisic acid. Patch-clamp studies on guard cell protoplasts isolated from atalmt12 mutants revealed reduced R-type currents compared with wild-type plants when malate is present in the bath media. Following expression of AtALMT12 in Xenopus oocytes, voltage-dependent anion currents reminiscent to R-type channels could be activated. In line with the features of the R-type channel, the activity of heterologously expressed AtALMT12 depends on extracellular malate. Thereby this key metabolite and osmolite of guard cells shifts the threshold for voltage activation of AtALMT12 towards more hyperpolarized potentials. R-Type channels, like voltage-dependent cation channels in nerve cells, are capable of transiently depolarizing guard cells, and thus could trigger membrane potential oscillations, action potentials and initiate long-term anion and K(+) efflux via SLAC1 and GORK, respectively.

  @article{RN190, abstract = {Stomatal pores formed by a pair of guard cells in the leaf epidermis control gas exchange and transpirational water loss. Stomatal closure is mediated by the release of potassium and anions from guard cells. Anion efflux from guard cells involves slow (S-type) and rapid (R-type) anion channels. Recently the SLAC1 gene has been shown to encode the slow, voltage-independent anion channel component in guard cells. In contrast, the R-type channel still awaits identification. Here, we show that AtALMT12, a member of the aluminum activated malate transporter family in Arabidopsis, represents a guard cell R-type anion channel. AtALMT12 is highly expressed in guard cells and is targeted to the plasma membrane. Plants lacking AtALMT12 are impaired in dark- and CO₂ -induced stomatal closure, as well as in response to the drought-stress hormone abscisic acid. Patch-clamp studies on guard cell protoplasts isolated from atalmt12 mutants revealed reduced R-type currents compared with wild-type plants when malate is present in the bath media. Following expression of AtALMT12 in Xenopus oocytes, voltage-dependent anion currents reminiscent to R-type channels could be activated. In line with the features of the R-type channel, the activity of heterologously expressed AtALMT12 depends on extracellular malate. Thereby this key metabolite and osmolite of guard cells shifts the threshold for voltage activation of AtALMT12 towards more hyperpolarized potentials. R-Type channels, like voltage-dependent cation channels in nerve cells, are capable of transiently depolarizing guard cells, and thus could trigger membrane potential oscillations, action potentials and initiate long-term anion and K(+) efflux via SLAC1 and GORK, respectively.}, author = {Meyer, S. and Mumm, P. and Imes, D. and Endler, A. and Weder, B. and Al-Rasheid, K. A. and Geiger, D. and Marten, I. and Martinoia, E. and Hedrich, R.}, journal = {Plant J}, keywords = {myOwn}, number = 6, pages = {1054-62}, title = {AtALMT12 represents an R-type anion channel required for stomatal movement in Arabidopsis guard cells}, type = {Journal Article}, volume = 63, year = 2010 }

  %0 Journal Article %1 RN190 %A Meyer, S. %A Mumm, P. %A Imes, D. %A Endler, A. %A Weder, B. %A Al-Rasheid, K. A. %A Geiger, D. %A Marten, I. %A Martinoia, E. %A Hedrich, R. %D 2010 %J Plant J %N 6 %P 1054-62 %R 10.1111/j.1365-313X.2010.04302.x %T AtALMT12 represents an R-type anion channel required for stomatal movement in Arabidopsis guard cells %U http://www.ncbi.nlm.nih.gov/pubmed/20626656 %V 63 %X Stomatal pores formed by a pair of guard cells in the leaf epidermis control gas exchange and transpirational water loss. Stomatal closure is mediated by the release of potassium and anions from guard cells. Anion efflux from guard cells involves slow (S-type) and rapid (R-type) anion channels. Recently the SLAC1 gene has been shown to encode the slow, voltage-independent anion channel component in guard cells. In contrast, the R-type channel still awaits identification. Here, we show that AtALMT12, a member of the aluminum activated malate transporter family in Arabidopsis, represents a guard cell R-type anion channel. AtALMT12 is highly expressed in guard cells and is targeted to the plasma membrane. Plants lacking AtALMT12 are impaired in dark- and CO₂ -induced stomatal closure, as well as in response to the drought-stress hormone abscisic acid. Patch-clamp studies on guard cell protoplasts isolated from atalmt12 mutants revealed reduced R-type currents compared with wild-type plants when malate is present in the bath media. Following expression of AtALMT12 in Xenopus oocytes, voltage-dependent anion currents reminiscent to R-type channels could be activated. In line with the features of the R-type channel, the activity of heterologously expressed AtALMT12 depends on extracellular malate. Thereby this key metabolite and osmolite of guard cells shifts the threshold for voltage activation of AtALMT12 towards more hyperpolarized potentials. R-Type channels, like voltage-dependent cation channels in nerve cells, are capable of transiently depolarizing guard cells, and thus could trigger membrane potential oscillations, action potentials and initiate long-term anion and K(+) efflux via SLAC1 and GORK, respectively.
• Carpaneto, A., Koepsell, H., Bamberg, E., Hedrich, R., und Geiger, D. (2010) „Sucrose- and H+-Dependent charge movements associated with the gating of sucrose transporter ZmSUT1“, PLoS ONE, 5(9), 1–10, verfügbar unter: https://doi.org/10.1371/journal.pone.0012605.
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  @article{RN164, author = {Carpaneto, A. and Koepsell, H. and Bamberg, E. and Hedrich, R. and Geiger, D.}, journal = {PLoS ONE}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2010,title = {Sucrose- and H+-Dependent charge movements associated with the gating of sucrose transporter ZmSUT1},journal = {PLoS ONE},year = {2010},volume = {5},number = {9},pages = {1-10},author = {Carpaneto, A. and Koepsell, H. and Bamberg, E. and Hedrich, R. and Geiger, D.}}]}, number = 9, pages = {1-10}, title = {Sucrose- and H+-Dependent charge movements associated with the gating of sucrose transporter ZmSUT1}, type = {Journal Article}, volume = 5, year = 2010 }

  %0 Journal Article %1 RN164 %A Carpaneto, A. %A Koepsell, H. %A Bamberg, E. %A Hedrich, R. %A Geiger, D. %D 2010 %J PLoS ONE %N 9 %P 1-10 %R 10.1371/journal.pone.0012605 %T Sucrose- and H+-Dependent charge movements associated with the gating of sucrose transporter ZmSUT1 %U http://www.scopus.com/inward/record.url?eid=2-s2.0-77958589601&partnerID=MN8TOARS %V 5
• Marcel, D., Müller, T., Hedrich, R., und Geiger, D. (2010) „K+ transport characteristics of the plasma membrane tandem-pore channel TPK4 and pore chimeras with its vacuolar homologs“, FEBS Letters, 584(11), 2433–2439, verfügbar unter: https://doi.org/10.1016/j.febslet.2010.04.038.
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  @article{RN162, author = {Marcel, D. and Müller, T. and Hedrich, R. and Geiger, D.}, journal = {FEBS Letters}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2010,title = {K+ transport characteristics of the plasma membrane tandem-pore channel TPK4 and pore chimeras with its vacuolar homologs},journal = {FEBS Letters},year = {2010},volume = {584},number = {11},pages = {2433-2439},author = {Marcel, D. and Müller, T. and Hedrich, R. and Geiger, D.}}]}, number = 11, pages = {2433-2439}, title = {K+ transport characteristics of the plasma membrane tandem-pore channel TPK4 and pore chimeras with its vacuolar homologs}, type = {Journal Article}, volume = 584, year = 2010 }

  %0 Journal Article %1 RN162 %A Marcel, D. %A Müller, T. %A Hedrich, R. %A Geiger, D. %D 2010 %J FEBS Letters %N 11 %P 2433-2439 %R 10.1016/j.febslet.2010.04.038 %T K+ transport characteristics of the plasma membrane tandem-pore channel TPK4 and pore chimeras with its vacuolar homologs %U http://www.scopus.com/inward/record.url?eid=2-s2.0-77952955264&partnerID=MN8TOARS %V 584
• Geiger, D., Scherzer, S., Mumm, P., Marten, I., Ache, P., Matschi, S., Liese, A., Wellmann, C., Al-Rasheid, K., Grill, E., Romeis, T., und Hedrich, R. (2010) „Guard cell anion channel SLAC1 is regulated by CDPK protein kinases with distinct Ca2+ affinities“, Proceedings of the National Academy of Sciences of the United States of America, 107(17), 8023–8028, verfügbar unter: https://doi.org/10.1073/pnas.0912030107.
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  @article{RN167, author = {Geiger, D. and Scherzer, S. and Mumm, P. and Marten, I. and Ache, P. and Matschi, S. and Liese, A. and Wellmann, C. and Al-Rasheid, K.A.S. and Grill, E. and Romeis, T. and Hedrich, R.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2010,title = {Guard cell anion channel SLAC1 is regulated by CDPK protein kinases with distinct Ca2+ affinities},journal = {Proceedings of the National Academy of Sciences of the United States of America},year = {2010},volume = {107},number = {17},pages = {8023-8028},author = {Geiger, D. and Scherzer, S. and Mumm, P. and Marten, I. and Ache, P. and Matschi, S. and Liese, A. and Wellmann, C. and Al-Rasheid, K.A.S. and Grill, E. and Romeis, T. and Hedrich, R.}}]}, number = 17, pages = {8023-8028}, title = {Guard cell anion channel SLAC1 is regulated by CDPK protein kinases with distinct Ca2+ affinities}, type = {Journal Article}, volume = 107, year = 2010 }

  %0 Journal Article %1 RN167 %A Geiger, D. %A Scherzer, S. %A Mumm, P. %A Marten, I. %A Ache, P. %A Matschi, S. %A Liese, A. %A Wellmann, C. %A Al-Rasheid, K.A.S. %A Grill, E. %A Romeis, T. %A Hedrich, R. %D 2010 %J Proceedings of the National Academy of Sciences of the United States of America %N 17 %P 8023-8028 %R 10.1073/pnas.0912030107 %T Guard cell anion channel SLAC1 is regulated by CDPK protein kinases with distinct Ca2+ affinities %U http://www.scopus.com/inward/record.url?eid=2-s2.0-77952399249&partnerID=MN8TOARS %V 107

• Geiger, D., Scherzer, S., Mumm, P., Stange, A., Marten, I., Bauer, H., Ache, P., Matschi, S., Liese, A., Al-Rasheid, K.A., Romeis, T., und Hedrich, R. (2009) „Activity of guard cell anion channel SLAC1 is controlled by drought-stress signaling kinase-phosphatase pair“, Proc Natl Acad Sci U S A, 106(50), 21425–30, verfügbar unter: https://doi.org/10.1073/pnas.0912021106.
  • [ Abstract ]
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  In response to drought stress the phytohormone ABA (abscisic acid) induces stomatal closure and, therein, activates guard cell anion channels in a calcium-dependent as well as-independent manner. Two key components of the ABA signaling pathway are the protein kinase OST1 (open stomata 1) and the protein phosphatase ABI1 (ABA insensitive 1). The recently identified guard cell anion channel SLAC1 appeared to be the key ion channel in this signaling pathway but remained electrically silent when expressed heterologously. Using split YFP assays, we identified OST1 as an interaction partner of SLAC1 and ABI1. Upon coexpression of SLAC1 with OST1 in Xenopus oocytes, SLAC1-related anion currents appeared similar to those observed in guard cells. Integration of ABI1 into the SLAC1/OST1 complex, however, prevented SLAC1 activation. Our studies demonstrate that SLAC1 represents the slow, deactivating, weak voltage-dependent anion channel of guard cells controlled by phosphorylation/dephosphorylation.

  @article{RN191, abstract = {In response to drought stress the phytohormone ABA (abscisic acid) induces stomatal closure and, therein, activates guard cell anion channels in a calcium-dependent as well as-independent manner. Two key components of the ABA signaling pathway are the protein kinase OST1 (open stomata 1) and the protein phosphatase ABI1 (ABA insensitive 1). The recently identified guard cell anion channel SLAC1 appeared to be the key ion channel in this signaling pathway but remained electrically silent when expressed heterologously. Using split YFP assays, we identified OST1 as an interaction partner of SLAC1 and ABI1. Upon coexpression of SLAC1 with OST1 in Xenopus oocytes, SLAC1-related anion currents appeared similar to those observed in guard cells. Integration of ABI1 into the SLAC1/OST1 complex, however, prevented SLAC1 activation. Our studies demonstrate that SLAC1 represents the slow, deactivating, weak voltage-dependent anion channel of guard cells controlled by phosphorylation/dephosphorylation.}, author = {Geiger, D. and Scherzer, S. and Mumm, P. and Stange, A. and Marten, I. and Bauer, H. and Ache, P. and Matschi, S. and Liese, A. and Al-Rasheid, K. A. and Romeis, T. and Hedrich, R.}, journal = {Proc Natl Acad Sci U S A}, keywords = {myOwn}, number = 50, pages = {21425-30}, title = {Activity of guard cell anion channel SLAC1 is controlled by drought-stress signaling kinase-phosphatase pair}, type = {Journal Article}, volume = 106, year = 2009 }

  %0 Journal Article %1 RN191 %A Geiger, D. %A Scherzer, S. %A Mumm, P. %A Stange, A. %A Marten, I. %A Bauer, H. %A Ache, P. %A Matschi, S. %A Liese, A. %A Al-Rasheid, K. A. %A Romeis, T. %A Hedrich, R. %D 2009 %J Proc Natl Acad Sci U S A %N 50 %P 21425-30 %R 10.1073/pnas.0912021106 %T Activity of guard cell anion channel SLAC1 is controlled by drought-stress signaling kinase-phosphatase pair %U http://www.ncbi.nlm.nih.gov/pubmed/19955405 %V 106 %X In response to drought stress the phytohormone ABA (abscisic acid) induces stomatal closure and, therein, activates guard cell anion channels in a calcium-dependent as well as-independent manner. Two key components of the ABA signaling pathway are the protein kinase OST1 (open stomata 1) and the protein phosphatase ABI1 (ABA insensitive 1). The recently identified guard cell anion channel SLAC1 appeared to be the key ion channel in this signaling pathway but remained electrically silent when expressed heterologously. Using split YFP assays, we identified OST1 as an interaction partner of SLAC1 and ABI1. Upon coexpression of SLAC1 with OST1 in Xenopus oocytes, SLAC1-related anion currents appeared similar to those observed in guard cells. Integration of ABI1 into the SLAC1/OST1 complex, however, prevented SLAC1 activation. Our studies demonstrate that SLAC1 represents the slow, deactivating, weak voltage-dependent anion channel of guard cells controlled by phosphorylation/dephosphorylation.
• Geiger, D., Becker, D., Vosloh, D., Gambale, F., Palme, K., Rehers, M., Anschuetz, U., Dreyer, I., Kudla, J., und Hedrich, R. (2009) „Heteromeric AtKC1·AKT1 channels in Arabidopsis roots facilitate growth under K+-limiting conditions“, Journal of Biological Chemistry, 284(32), 21288–21295, verfügbar unter: https://doi.org/10.1074/jbc.M109.017574.
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  @article{RN159, author = {Geiger, D. and Becker, D. and Vosloh, D. and Gambale, F. and Palme, K. and Rehers, M. and Anschuetz, U. and Dreyer, I. and Kudla, J. and Hedrich, R.}, journal = {Journal of Biological Chemistry}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2009,title = {Heteromeric AtKC1·AKT1 channels in Arabidopsis roots facilitate growth under K+-limiting conditions},journal = {Journal of Biological Chemistry},year = {2009},volume = {284},number = {32},pages = {21288-21295},author = {Geiger, D. and Becker, D. and Vosloh, D. and Gambale, F. and Palme, K. and Rehers, M. and Anschuetz, U. and Dreyer, I. and Kudla, J. and Hedrich, R.}}]}, number = 32, pages = {21288-21295}, title = {Heteromeric AtKC1·AKT1 channels in Arabidopsis roots facilitate growth under K+-limiting conditions}, type = {Journal Article}, volume = 284, year = 2009 }

  %0 Journal Article %1 RN159 %A Geiger, D. %A Becker, D. %A Vosloh, D. %A Gambale, F. %A Palme, K. %A Rehers, M. %A Anschuetz, U. %A Dreyer, I. %A Kudla, J. %A Hedrich, R. %D 2009 %J Journal of Biological Chemistry %N 32 %P 21288-21295 %R 10.1074/jbc.M109.017574 %T Heteromeric AtKC1·AKT1 channels in Arabidopsis roots facilitate growth under K+-limiting conditions %U http://www.scopus.com/inward/record.url?eid=2-s2.0-69249120225&partnerID=MN8TOARS %V 284

• Carpaneto, A., Geiger, D., Bamberg, E., Sauer, N., Fromm, J., und Hedrich, R. (2005) „Phloem-localized, proton-coupled sucrose carrier ZmSUT1 mediates sucrose efflux under the control of the sucrose gradient and the proton motive force“, Journal of Biological Chemistry, 280(22), 21437–21443, verfügbar unter: https://doi.org/10.1074/jbc.M501785200.
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  @article{RN163, author = {Carpaneto, A. and Geiger, D. and Bamberg, E. and Sauer, N. and Fromm, J. and Hedrich, R.}, journal = {Journal of Biological Chemistry}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2005,title = {Phloem-localized, proton-coupled sucrose carrier ZmSUT1 mediates sucrose efflux under the control of the sucrose gradient and the proton motive force},journal = {Journal of Biological Chemistry},year = {2005},volume = {280},number = {22},pages = {21437-21443},author = {Carpaneto, A. and Geiger, D. and Bamberg, E. and Sauer, N. and Fromm, J. and Hedrich, R.}}]}, number = 22, pages = {21437-21443}, title = {Phloem-localized, proton-coupled sucrose carrier ZmSUT1 mediates sucrose efflux under the control of the sucrose gradient and the proton motive force}, type = {Journal Article}, volume = 280, year = 2005 }

  %0 Journal Article %1 RN163 %A Carpaneto, A. %A Geiger, D. %A Bamberg, E. %A Sauer, N. %A Fromm, J. %A Hedrich, R. %D 2005 %J Journal of Biological Chemistry %N 22 %P 21437-21443 %R 10.1074/jbc.M501785200 %T Phloem-localized, proton-coupled sucrose carrier ZmSUT1 mediates sucrose efflux under the control of the sucrose gradient and the proton motive force %U http://www.scopus.com/inward/record.url?eid=2-s2.0-20444427207&partnerID=MN8TOARS %V 280
• Klepek, Y.S., Geiger, D., Stadler, R., Klebl, F., Landouar-Arsivaud, L., Lemoine, R., Hedrich, R., und Sauer, N. (2005) „Arabidopsis POLYOL TRANSPORTER5, a new member of the monosaccharide transporter-like superfamily, mediates H+-Symport of numerous substrates, including myo-inositol, glycerol, and ribose“, Plant Cell, 17(1), 204–18, verfügbar unter: https://doi.org/10.1105/tpc.104.026641.
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  Six genes of the Arabidopsis thaliana monosaccharide transporter-like (MST-like) superfamily share significant homology with polyol transporter genes previously identified in plants translocating polyols (mannitol or sorbitol) in their phloem (celery [Apium graveolens], common plantain [Plantago major], or sour cherry [Prunus cerasus]). The physiological role and the functional properties of this group of proteins were unclear in Arabidopsis, which translocates sucrose and small amounts of raffinose rather than polyols. Here, we describe POLYOL TRANSPORTER5 (AtPLT5), the first member of this subgroup of Arabidopsis MST-like transporters. Transient expression of an AtPLT5-green fluorescent protein fusion in plant cells and functional analyses of the AtPLT5 protein in yeast and Xenopus oocytes demonstrate that AtPLT5 is located in the plasma membrane and characterize this protein as a broad-spectrum H+-symporter for linear polyols, such as sorbitol, xylitol, erythritol, or glycerol. Unexpectedly, however, AtPLT5 catalyzes also the transport of the cyclic polyol myo-inositol and of different hexoses and pentoses, including ribose, a sugar that is not transported by any of the previously characterized plant sugar transporters. RT-PCR analyses and AtPLT5 promoter-reporter gene plants revealed that AtPLT5 is most strongly expressed in Arabidopsis roots, but also in the vascular tissue of leaves and in specific floral organs. The potential physiological role of AtPLT5 is discussed.

  @article{RN192, abstract = {Six genes of the Arabidopsis thaliana monosaccharide transporter-like (MST-like) superfamily share significant homology with polyol transporter genes previously identified in plants translocating polyols (mannitol or sorbitol) in their phloem (celery [Apium graveolens], common plantain [Plantago major], or sour cherry [Prunus cerasus]). The physiological role and the functional properties of this group of proteins were unclear in Arabidopsis, which translocates sucrose and small amounts of raffinose rather than polyols. Here, we describe POLYOL TRANSPORTER5 (AtPLT5), the first member of this subgroup of Arabidopsis MST-like transporters. Transient expression of an AtPLT5-green fluorescent protein fusion in plant cells and functional analyses of the AtPLT5 protein in yeast and Xenopus oocytes demonstrate that AtPLT5 is located in the plasma membrane and characterize this protein as a broad-spectrum H+-symporter for linear polyols, such as sorbitol, xylitol, erythritol, or glycerol. Unexpectedly, however, AtPLT5 catalyzes also the transport of the cyclic polyol myo-inositol and of different hexoses and pentoses, including ribose, a sugar that is not transported by any of the previously characterized plant sugar transporters. RT-PCR analyses and AtPLT5 promoter-reporter gene plants revealed that AtPLT5 is most strongly expressed in Arabidopsis roots, but also in the vascular tissue of leaves and in specific floral organs. The potential physiological role of AtPLT5 is discussed.}, author = {Klepek, Y. S. and Geiger, D. and Stadler, R. and Klebl, F. and Landouar-Arsivaud, L. and Lemoine, R. and Hedrich, R. and Sauer, N.}, journal = {Plant Cell}, keywords = {myOwn}, number = 1, pages = {204-18}, title = {Arabidopsis POLYOL TRANSPORTER5, a new member of the monosaccharide transporter-like superfamily, mediates H+-Symport of numerous substrates, including myo-inositol, glycerol, and ribose}, type = {Journal Article}, volume = 17, year = 2005 }

  %0 Journal Article %1 RN192 %A Klepek, Y. S. %A Geiger, D. %A Stadler, R. %A Klebl, F. %A Landouar-Arsivaud, L. %A Lemoine, R. %A Hedrich, R. %A Sauer, N. %D 2005 %J Plant Cell %N 1 %P 204-18 %R 10.1105/tpc.104.026641 %T Arabidopsis POLYOL TRANSPORTER5, a new member of the monosaccharide transporter-like superfamily, mediates H+-Symport of numerous substrates, including myo-inositol, glycerol, and ribose %U http://www.ncbi.nlm.nih.gov/pubmed/15598803 %V 17 %X Six genes of the Arabidopsis thaliana monosaccharide transporter-like (MST-like) superfamily share significant homology with polyol transporter genes previously identified in plants translocating polyols (mannitol or sorbitol) in their phloem (celery [Apium graveolens], common plantain [Plantago major], or sour cherry [Prunus cerasus]). The physiological role and the functional properties of this group of proteins were unclear in Arabidopsis, which translocates sucrose and small amounts of raffinose rather than polyols. Here, we describe POLYOL TRANSPORTER5 (AtPLT5), the first member of this subgroup of Arabidopsis MST-like transporters. Transient expression of an AtPLT5-green fluorescent protein fusion in plant cells and functional analyses of the AtPLT5 protein in yeast and Xenopus oocytes demonstrate that AtPLT5 is located in the plasma membrane and characterize this protein as a broad-spectrum H+-symporter for linear polyols, such as sorbitol, xylitol, erythritol, or glycerol. Unexpectedly, however, AtPLT5 catalyzes also the transport of the cyclic polyol myo-inositol and of different hexoses and pentoses, including ribose, a sugar that is not transported by any of the previously characterized plant sugar transporters. RT-PCR analyses and AtPLT5 promoter-reporter gene plants revealed that AtPLT5 is most strongly expressed in Arabidopsis roots, but also in the vascular tissue of leaves and in specific floral organs. The potential physiological role of AtPLT5 is discussed.

• Langer, K., Levchenko, V., Fromm, J., Geiger, D., Steinmeyer, R., Lautner, S., Ache, P., und Hedrich, R. (2004) „The poplar K+ channel KPT1 is associated with K+ uptake during stomatal opening and bud development“, Plant Journal, 37(6), 828–838, verfügbar unter: https://doi.org/10.1111/j.0960-7412.2003.02008.x.
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  @article{RN160, author = {Langer, K. and Levchenko, V. and Fromm, J. and Geiger, D. and Steinmeyer, R. and Lautner, S. and Ache, P. and Hedrich, R.}, journal = {Plant Journal}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2004,title = {The poplar K+ channel KPT1 is associated with K+ uptake during stomatal opening and bud development},journal = {Plant Journal},year = {2004},volume = {37},number = {6},pages = {828-838},author = {Langer, K. and Levchenko, V. and Fromm, J. and Geiger, D. and Steinmeyer, R. and Lautner, S. and Ache, P. and Hedrich, R.}}]}, number = 6, pages = {828-838}, title = {The poplar K+ channel KPT1 is associated with K+ uptake during stomatal opening and bud development}, type = {Journal Article}, volume = 37, year = 2004 }

  %0 Journal Article %1 RN160 %A Langer, K. %A Levchenko, V. %A Fromm, J. %A Geiger, D. %A Steinmeyer, R. %A Lautner, S. %A Ache, P. %A Hedrich, R. %D 2004 %J Plant Journal %N 6 %P 828-838 %R 10.1111/j.0960-7412.2003.02008.x %T The poplar K+ channel KPT1 is associated with K+ uptake during stomatal opening and bud development %U http://www.scopus.com/inward/record.url?eid=2-s2.0-1642310581&partnerID=MN8TOARS %V 37
• Becker, D., Geiger, D., Dunkel, M., Roller, A., Bertl, A., Latz, A., Carpaneto, A., Dietrich, P., Roelfsema, M., Voelker, C., Schmidt, D., Mueller-Roeber, B., Czempinski, K., und Hedrich, R. (2004) „AtTPK4, an Arabidopsis tandem-pore K+ channel, poised to control the pollen membrane voltage in a pH- and Ca2+-dependent manner“, Proceedings of the National Academy of Sciences of the United States of America, 101(44), 15621–15626, verfügbar unter: https://doi.org/10.1073/pnas.0401502101.
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  @article{RN166, author = {Becker, D. and Geiger, D. and Dunkel, M. and Roller, A. and Bertl, A. and Latz, A. and Carpaneto, A. and Dietrich, P. and Roelfsema, M.R.G. and Voelker, C. and Schmidt, D. and Mueller-Roeber, B. and Czempinski, K. and Hedrich, R.}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2004,title = {AtTPK4, an Arabidopsis tandem-pore K+ channel, poised to control the pollen membrane voltage in a pH- and Ca2+-dependent manner},journal = {Proceedings of the National Academy of Sciences of the United States of America},year = {2004},volume = {101},number = {44},pages = {15621-15626},author = {Becker, D. and Geiger, D. and Dunkel, M. and Roller, A. and Bertl, A. and Latz, A. and Carpaneto, A. and Dietrich, P. and Roelfsema, M.R.G. and Voelker, C. and Schmidt, D. and Mueller-Roeber, B. and Czempinski, K. and Hedrich, R.}}]}, number = 44, pages = {15621-15626}, title = {AtTPK4, an Arabidopsis tandem-pore K+ channel, poised to control the pollen membrane voltage in a pH- and Ca2+-dependent manner}, type = {Journal Article}, volume = 101, year = 2004 }

  %0 Journal Article %1 RN166 %A Becker, D. %A Geiger, D. %A Dunkel, M. %A Roller, A. %A Bertl, A. %A Latz, A. %A Carpaneto, A. %A Dietrich, P. %A Roelfsema, M.R.G. %A Voelker, C. %A Schmidt, D. %A Mueller-Roeber, B. %A Czempinski, K. %A Hedrich, R. %D 2004 %J Proceedings of the National Academy of Sciences of the United States of America %N 44 %P 15621-15626 %R 10.1073/pnas.0401502101 %T AtTPK4, an Arabidopsis tandem-pore K+ channel, poised to control the pollen membrane voltage in a pH- and Ca2+-dependent manner %U http://www.scopus.com/inward/record.url?eid=2-s2.0-8144228134&partnerID=MN8TOARS %V 101
• Diatloff, E., Geiger, D., Shang, L., Hedrich, R., und Roberts, S. (2004) „Differential regulation of K+ channels in Arabidopsis epidermal and stelar root cells“, Plant, Cell and Environment, 27(8), 980–990, verfügbar unter: https://doi.org/10.1111/j.1365-3040.2004.01201.x.
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  @article{RN170, author = {Diatloff, E. and Geiger, D. and Shang, L. and Hedrich, R. and Roberts, S.K.}, journal = {Plant, Cell and Environment}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2004,title = {Differential regulation of K+ channels in Arabidopsis epidermal and stelar root cells},journal = {Plant, Cell and Environment},year = {2004},volume = {27},number = {8},pages = {980-990},author = {Diatloff, E. and Geiger, D. and Shang, L. and Hedrich, R. and Roberts, S.K.}}]}, number = 8, pages = {980-990}, title = {Differential regulation of K+ channels in Arabidopsis epidermal and stelar root cells}, type = {Journal Article}, volume = 27, year = 2004 }

  %0 Journal Article %1 RN170 %A Diatloff, E. %A Geiger, D. %A Shang, L. %A Hedrich, R. %A Roberts, S.K. %D 2004 %J Plant, Cell and Environment %N 8 %P 980-990 %R 10.1111/j.1365-3040.2004.01201.x %T Differential regulation of K+ channels in Arabidopsis epidermal and stelar root cells %U http://www.scopus.com/inward/record.url?eid=2-s2.0-3843094793&partnerID=MN8TOARS %V 27
• Ramsperger-Gleixner, M., Geiger, D., Hedrich, R., und Sauer, N. (2004) „Differential Expression of Sucrose Transporter and Polyol Transporter Genes during Maturation of Common Plantain Companion Cells“, Plant Physiology, 134(1), 147–160, verfügbar unter: https://doi.org/10.1104/pp.103.027136.
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  @article{RN176, author = {Ramsperger-Gleixner, M. and Geiger, D. and Hedrich, R. and Sauer, N.}, journal = {Plant Physiology}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2004,title = {Differential Expression of Sucrose Transporter and Polyol Transporter Genes during Maturation of Common Plantain Companion Cells},journal = {Plant Physiology},year = {2004},volume = {134},number = {1},pages = {147-160},author = {Ramsperger-Gleixner, M. and Geiger, D. and Hedrich, R. and Sauer, N.}}]}, number = 1, pages = {147-160}, title = {Differential Expression of Sucrose Transporter and Polyol Transporter Genes during Maturation of Common Plantain Companion Cells}, type = {Journal Article}, volume = 134, year = 2004 }

  %0 Journal Article %1 RN176 %A Ramsperger-Gleixner, M. %A Geiger, D. %A Hedrich, R. %A Sauer, N. %D 2004 %J Plant Physiology %N 1 %P 147-160 %R 10.1104/pp.103.027136 %T Differential Expression of Sucrose Transporter and Polyol Transporter Genes during Maturation of Common Plantain Companion Cells %U http://www.scopus.com/inward/record.url?eid=2-s2.0-0842285689&partnerID=MN8TOARS %V 134

• Philippar, K., Büchsenschutz, K., Abshagen, M., Fuchs, I., Geiger, D., Lacombe, B., und Hedrich, R. (2003) „The K+ channel KZM1 mediates potassium uptake into the phloem and guard cells of the C4 grass Zea mays“, J Biol Chem, 278(19), 16973–81, verfügbar unter: https://doi.org/10.1074/jbc.M212720200.
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  In search of K(+) channel genes expressed in the leaf of the C(4) plant Zea mays, we isolated the cDNA of KZM1 (for K(+) channel Zea mays 1). KZM1 showed highest similarity to the Arabidopsis K(+) channels KAT1 and KAT2, which are localized in guard cells and phloem. When expressed in Xenopus oocytes, KZM1 exhibited the characteristic features of an inward-rectifying, potassium-selective channel. In contrast to KAT1- and KAT2-type K(+) channels, however, KZM1 currents were insensitive to external pH changes. Northern blot analyses identified the leaf, nodes, and silks as sites of KZM1 expression. Following the separation of maize leaves into epidermal, mesophyll, and vascular fractions, quantitative real-time reverse transcriptase-PCR allowed us to localize KZM1 transcripts predominantly in vascular strands and the epidermis. Cell tissue separation and KZM1 localization were followed with marker genes such as the bundle sheath-specific ribulose-1,5-bisphosphate carboxylase, the phloem K(+) channel ZMK2, and the putative sucrose transporter ZmSUT1. When expressed in Xenopus oocytes, ZmSUT1 mediated proton-coupled sucrose symport. Coexpression of ZmSUT1 with the phloem K(+) channels KZM1 and ZMK2 revealed that ZMK2 is able to stabilize the membrane potential during phloem loading/unloading processes and KZM1 to mediate K(+) uptake. During leaf development, sink-source transitions, and diurnal changes, KZM1 is constitutively expressed, pointing to a housekeeping function of this channel in K(+) homeostasis of the maize leaf. Therefore, the voltage-dependent K(+)-uptake channel KZM1 seems to mediate K(+) retrieval and K(+) loading into the phloem as well as K(+)-dependent stomatal opening.

  @article{RN193, abstract = {In search of K(+) channel genes expressed in the leaf of the C(4) plant Zea mays, we isolated the cDNA of KZM1 (for K(+) channel Zea mays 1). KZM1 showed highest similarity to the Arabidopsis K(+) channels KAT1 and KAT2, which are localized in guard cells and phloem. When expressed in Xenopus oocytes, KZM1 exhibited the characteristic features of an inward-rectifying, potassium-selective channel. In contrast to KAT1- and KAT2-type K(+) channels, however, KZM1 currents were insensitive to external pH changes. Northern blot analyses identified the leaf, nodes, and silks as sites of KZM1 expression. Following the separation of maize leaves into epidermal, mesophyll, and vascular fractions, quantitative real-time reverse transcriptase-PCR allowed us to localize KZM1 transcripts predominantly in vascular strands and the epidermis. Cell tissue separation and KZM1 localization were followed with marker genes such as the bundle sheath-specific ribulose-1,5-bisphosphate carboxylase, the phloem K(+) channel ZMK2, and the putative sucrose transporter ZmSUT1. When expressed in Xenopus oocytes, ZmSUT1 mediated proton-coupled sucrose symport. Coexpression of ZmSUT1 with the phloem K(+) channels KZM1 and ZMK2 revealed that ZMK2 is able to stabilize the membrane potential during phloem loading/unloading processes and KZM1 to mediate K(+) uptake. During leaf development, sink-source transitions, and diurnal changes, KZM1 is constitutively expressed, pointing to a housekeeping function of this channel in K(+) homeostasis of the maize leaf. Therefore, the voltage-dependent K(+)-uptake channel KZM1 seems to mediate K(+) retrieval and K(+) loading into the phloem as well as K(+)-dependent stomatal opening.}, author = {Philippar, K. and Büchsenschutz, K. and Abshagen, M. and Fuchs, I. and Geiger, D. and Lacombe, B. and Hedrich, R.}, journal = {J Biol Chem}, keywords = {myOwn}, number = 19, pages = {16973-81}, title = {The K+ channel KZM1 mediates potassium uptake into the phloem and guard cells of the C4 grass Zea mays}, type = {Journal Article}, volume = 278, year = 2003 }

  %0 Journal Article %1 RN193 %A Philippar, K. %A Büchsenschutz, K. %A Abshagen, M. %A Fuchs, I. %A Geiger, D. %A Lacombe, B. %A Hedrich, R. %D 2003 %J J Biol Chem %N 19 %P 16973-81 %R 10.1074/jbc.M212720200 %T The K+ channel KZM1 mediates potassium uptake into the phloem and guard cells of the C4 grass Zea mays %U http://www.ncbi.nlm.nih.gov/pubmed/12611901 %V 278 %X In search of K(+) channel genes expressed in the leaf of the C(4) plant Zea mays, we isolated the cDNA of KZM1 (for K(+) channel Zea mays 1). KZM1 showed highest similarity to the Arabidopsis K(+) channels KAT1 and KAT2, which are localized in guard cells and phloem. When expressed in Xenopus oocytes, KZM1 exhibited the characteristic features of an inward-rectifying, potassium-selective channel. In contrast to KAT1- and KAT2-type K(+) channels, however, KZM1 currents were insensitive to external pH changes. Northern blot analyses identified the leaf, nodes, and silks as sites of KZM1 expression. Following the separation of maize leaves into epidermal, mesophyll, and vascular fractions, quantitative real-time reverse transcriptase-PCR allowed us to localize KZM1 transcripts predominantly in vascular strands and the epidermis. Cell tissue separation and KZM1 localization were followed with marker genes such as the bundle sheath-specific ribulose-1,5-bisphosphate carboxylase, the phloem K(+) channel ZMK2, and the putative sucrose transporter ZmSUT1. When expressed in Xenopus oocytes, ZmSUT1 mediated proton-coupled sucrose symport. Coexpression of ZmSUT1 with the phloem K(+) channels KZM1 and ZMK2 revealed that ZMK2 is able to stabilize the membrane potential during phloem loading/unloading processes and KZM1 to mediate K(+) uptake. During leaf development, sink-source transitions, and diurnal changes, KZM1 is constitutively expressed, pointing to a housekeeping function of this channel in K(+) homeostasis of the maize leaf. Therefore, the voltage-dependent K(+)-uptake channel KZM1 seems to mediate K(+) retrieval and K(+) loading into the phloem as well as K(+)-dependent stomatal opening.

• Langer, K., Ache, P., Geiger, D., Stinzing, A., Arend, M., Wind, C., Regan, S., Fromm, J., und Hedrich, R. (2002) „Poplar potassium transporters capable of controlling K+ homeostasis and K+-dependent xylogenesis“, Plant Journal, 32(6), 997–1009, verfügbar unter: https://doi.org/10.1046/j.1365-313X.2002.01487.x.
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  @article{RN165, author = {Langer, K. and Ache, P. and Geiger, D. and Stinzing, A. and Arend, M. and Wind, C. and Regan, S. and Fromm, J. and Hedrich, R.}, journal = {Plant Journal}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2002,title = {Poplar potassium transporters capable of controlling K+ homeostasis and K+-dependent xylogenesis},journal = {Plant Journal},year = {2002},volume = {32},number = {6},pages = {997-1009},author = {Langer, K. and Ache, P. and Geiger, D. and Stinzing, A. and Arend, M. and Wind, C. and Regan, S. and Fromm, J. and Hedrich, R.}}]}, number = 6, pages = {997-1009}, title = {Poplar potassium transporters capable of controlling K+ homeostasis and K+-dependent xylogenesis}, type = {Journal Article}, volume = 32, year = 2002 }

  %0 Journal Article %1 RN165 %A Langer, K. %A Ache, P. %A Geiger, D. %A Stinzing, A. %A Arend, M. %A Wind, C. %A Regan, S. %A Fromm, J. %A Hedrich, R. %D 2002 %J Plant Journal %N 6 %P 997-1009 %R 10.1046/j.1365-313X.2002.01487.x %T Poplar potassium transporters capable of controlling K+ homeostasis and K+-dependent xylogenesis %U http://www.scopus.com/inward/record.url?eid=2-s2.0-0036949467&partnerID=MN8TOARS %V 32
• Geiger, D., Becker, D., Lacombe, B., und Hedrich, R. (2002) „Outer pore residues control the H+ and K+ sensitivity of the Arabidopsis potassium channel AKT3“, Plant Cell, 14(8), 1859–1868, verfügbar unter: https://doi.org/10.1105/tpc.003244.
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  @article{RN168, author = {Geiger, D. and Becker, D. and Lacombe, B. and Hedrich, R.}, journal = {Plant Cell}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2002,title = {Outer pore residues control the H+ and K+ sensitivity of the Arabidopsis potassium channel AKT3},journal = {Plant Cell},year = {2002},volume = {14},number = {8},pages = {1859-1868},author = {Geiger, D. and Becker, D. and Lacombe, B. and Hedrich, R.}}]}, number = 8, pages = {1859-1868}, title = {Outer pore residues control the H+ and K+ sensitivity of the Arabidopsis potassium channel AKT3}, type = {Journal Article}, volume = 14, year = 2002 }

  %0 Journal Article %1 RN168 %A Geiger, D. %A Becker, D. %A Lacombe, B. %A Hedrich, R. %D 2002 %J Plant Cell %N 8 %P 1859-1868 %R 10.1105/tpc.003244 %T Outer pore residues control the H+ and K+ sensitivity of the Arabidopsis potassium channel AKT3 %U http://www.scopus.com/inward/record.url?eid=2-s2.0-0036671321&partnerID=MN8TOARS %V 14
• Deeken, R., Geiger, D., Fromm, J., Koroleva, O., Ache, P., Langenfeld-Heyser, R., Sauer, N., May, S., und Hedrich, R. (2002) „Loss of the AKT2/3 potassium channel affects sugar loading into the phloem of Arabidopsis“, Planta, 216(2), 334–344, verfügbar unter: https://doi.org/10.1007/s00425-002-0895-1.
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  @article{RN171, author = {Deeken, R. and Geiger, D. and Fromm, J. and Koroleva, O. and Ache, P. and Langenfeld-Heyser, R. and Sauer, N. and May, S.T. and Hedrich, R.}, journal = {Planta}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2002,title = {Loss of the AKT2/3 potassium channel affects sugar loading into the phloem of Arabidopsis},journal = {Planta},year = {2002},volume = {216},number = {2},pages = {334-344},author = {Deeken, R. and Geiger, D. and Fromm, J. and Koroleva, O. and Ache, P. and Langenfeld-Heyser, R. and Sauer, N. and May, S.T. and Hedrich, R.}}]}, number = 2, pages = {334-344}, title = {Loss of the AKT2/3 potassium channel affects sugar loading into the phloem of Arabidopsis}, type = {Journal Article}, volume = 216, year = 2002 }

  %0 Journal Article %1 RN171 %A Deeken, R. %A Geiger, D. %A Fromm, J. %A Koroleva, O. %A Ache, P. %A Langenfeld-Heyser, R. %A Sauer, N. %A May, S.T. %A Hedrich, R. %D 2002 %J Planta %N 2 %P 334-344 %R 10.1007/s00425-002-0895-1 %T Loss of the AKT2/3 potassium channel affects sugar loading into the phloem of Arabidopsis %U http://www.scopus.com/inward/record.url?eid=2-s2.0-0036886861&partnerID=MN8TOARS %V 216

• Hoth, S., Geiger, D., Becker, D., und Hedrich, R. (2001) „The pore of plant k+ channels is involved in voltage and ph sensing: Domain-swapping between different k+ channel α-subunits“, Plant Cell, 13(4), 943–952, verfügbar unter: https://doi.org/10.1105/tpc.13.4.943.
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  @article{RN178, author = {Hoth, S. and Geiger, D. and Becker, D. and Hedrich, R.}, journal = {Plant Cell}, keywords = {myOwn}, note = {ORCID Reference type: [bibtex]; ORCID Reference: [@article { geiger2001,title = {The pore of plant k+ channels is involved in voltage and ph sensing: Domain-swapping between different k+ channel α-subunits},journal = {Plant Cell},year = {2001},volume = {13},number = {4},pages = {943-952},author = {Hoth, S. and Geiger, D. and Becker, D. and Hedrich, R.}}]}, number = 4, pages = {943-952}, title = {The pore of plant k+ channels is involved in voltage and ph sensing: Domain-swapping between different k+ channel α-subunits}, type = {Journal Article}, volume = 13, year = 2001 }

  %0 Journal Article %1 RN178 %A Hoth, S. %A Geiger, D. %A Becker, D. %A Hedrich, R. %D 2001 %J Plant Cell %N 4 %P 943-952 %R 10.1105/tpc.13.4.943 %T The pore of plant k+ channels is involved in voltage and ph sensing: Domain-swapping between different k+ channel α-subunits %U http://www.scopus.com/inward/record.url?eid=2-s2.0-0035040262&partnerID=MN8TOARS %V 13