A putative role for the plasma membrane potential in the control of the expression of the gene encoding the tomato high-affinity potassium transporter HAK5

A putative role for the plasma membrane potential in the control of the expression of the gene... A chimeric CaHAK1–LeHAK5 transporter with only 15 amino acids of CaHAK1 in the N-terminus mediates high-affinity K+ uptake in yeast cells. Kinetic and expression analyses strongly suggest that LeHAK5 mediates a significant proportion of the high-affinity K+ uptake shown by K+-starved tomato (Solanum lycopersicum) plants. The development of high-affinity K+ uptake, putatively mediated by LeHAK5, was correlated with increased LeHAK5 mRNA levels and a more negative electrical potential difference across the plasma membrane of root epidermal and cortical cells. However, this increase in high-affinity K+ uptake was not correlated with the root K+ content. Thus, (i) growth conditions that result in a hyperpolarized root plasma membrane potential, such as K+ starvation or growth in the presence of NH4 +, but which do not decrease the K+ content, lead to increased LeHAK5 expression; (ii) the presence of NaCl in the growth solution, which prevents the hyperpolarization induced by K+ starvation, also prevents LeHAK5 expression. Moreover, once the gene is induced, depolarization of the plasma membrane potential then produces a decrease in the LeHAK5 mRNA. On the basis of these results, we propose that the plant membrane electrical potential plays a role in the regulation of the expression of this gene encoding a high-affinity K+ transporter. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Plant Molecular Biology Springer Journals

A putative role for the plasma membrane potential in the control of the expression of the gene encoding the tomato high-affinity potassium transporter HAK5

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Publisher
Springer Journals
Copyright
Copyright © 2008 by Springer Science+Business Media B.V.
Subject
Life Sciences; Plant Pathology; Biochemistry, general; Plant Sciences
ISSN
0167-4412
eISSN
1573-5028
D.O.I.
10.1007/s11103-008-9388-3
Publisher site
See Article on Publisher Site

Abstract

A chimeric CaHAK1–LeHAK5 transporter with only 15 amino acids of CaHAK1 in the N-terminus mediates high-affinity K+ uptake in yeast cells. Kinetic and expression analyses strongly suggest that LeHAK5 mediates a significant proportion of the high-affinity K+ uptake shown by K+-starved tomato (Solanum lycopersicum) plants. The development of high-affinity K+ uptake, putatively mediated by LeHAK5, was correlated with increased LeHAK5 mRNA levels and a more negative electrical potential difference across the plasma membrane of root epidermal and cortical cells. However, this increase in high-affinity K+ uptake was not correlated with the root K+ content. Thus, (i) growth conditions that result in a hyperpolarized root plasma membrane potential, such as K+ starvation or growth in the presence of NH4 +, but which do not decrease the K+ content, lead to increased LeHAK5 expression; (ii) the presence of NaCl in the growth solution, which prevents the hyperpolarization induced by K+ starvation, also prevents LeHAK5 expression. Moreover, once the gene is induced, depolarization of the plasma membrane potential then produces a decrease in the LeHAK5 mRNA. On the basis of these results, we propose that the plant membrane electrical potential plays a role in the regulation of the expression of this gene encoding a high-affinity K+ transporter.

Journal

Plant Molecular BiologySpringer Journals

Published: Aug 27, 2008

References

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