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https://hdl.handle.net/2440/67223
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Type: | Journal article |
Title: | AtHKT1;1 mediates nernstian sodium channel transport properties in arabidopsis root stelar cells |
Author: | Xue, S. Yao, X. Luo, W. Jha, D. Tester, M. Horie, T. Schroeder, J.I. |
Citation: | PLoS One, 2011; 6(9):e24725-1-e24725-9 |
Publisher: | Public Library of Science |
Issue Date: | 2011 |
ISSN: | 1932-6203 1932-6203 |
Editor: | Baxter, I. |
Statement of Responsibility: | Shaowu Xue, Xuan Yao, Wei Luo, Deepa Jha, Mark Tester, Tomoaki Horie and Julian I. Schroeder |
Abstract: | The Arabidopsis AtHKT1;1 protein was identified as a sodium (Na+) transporter by heterologous expression in Xenopus laevis oocytes and Saccharomyces cerevisiae. However, direct comparative in vivo electrophysiological analyses of a plant HKT transporter in wild-type and hkt loss-of-function mutants has not yet been reported and it has been recently argued that heterologous expression systems may alter properties of plant transporters, including HKT transporters. In this report, we analyze several key functions of AtHKT1;1-mediated ion currents in their native root stelar cells, including Na+ and K+ conductances, AtHKT1;1-mediated outward currents, and shifts in reversal potentials in the presence of defined intracellular and extracellular salt concentrations. Enhancer trap Arabidopsis plants with GFP-labeled root stelar cells were used to investigate AtHKT1;1-dependent ion transport properties using patch clamp electrophysiology in wild-type and athkt1;1 mutant plants. AtHKT1;1-dependent currents were carried by sodium ions and these currents were not observed in athkt1;1 mutant stelar cells. However, K+ currents in wild-type and athkt1;1 root stelar cell protoplasts were indistinguishable correlating with the Na+ over K+ selectivity of AtHKT1;1-mediated transport. Moreover, AtHKT1;1-mediated currents did not show a strong voltage dependence in vivo. Unexpectedly, removal of extracellular Na+ caused a reduction in AtHKT1;1-mediated outward currents in Columbia root stelar cells and Xenopus oocytes, indicating a role for external Na+ in regulation of AtHKT1;1 activity. Shifting the NaCl gradient in root stelar cells showed a Nernstian shift in the reversal potential providing biophysical evidence for the model that AtHKT1;1 mediates passive Na+ channel transport properties. |
Keywords: | Plants, Genetically Modified Arabidopsis Plant Roots Sodium Sodium Channels Cation Transport Proteins Symporters Arabidopsis Proteins Patch-Clamp Techniques Gene Expression Regulation, Plant |
Rights: | © 2011 Xue et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
DOI: | 10.1371/journal.pone.0024725 |
Grant ID: | ARC |
Published version: | http://dx.doi.org/10.1371/journal.pone.0024725 |
Appears in Collections: | Agriculture, Food and Wine publications Aurora harvest 7 |
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