GrainGenes Reference Report: PPS-118-651
Reference
PPS-118-651
Title
Rapid up-regulation of HKT1, a high-affinity potassium transporter gene, in roots of barley and wheat following withdrawal of potassium.
Journal
Plant Physiology
Year
1998
Volume
118
Pages
651-659
Author
Wang TB Gassmann W Rubio F Schroeder JI Glass ADM
Abstract
High-affinity K+ uptake in plant roots is rapidly up-regulated when K+ is withheld and down-regulated when K+ is resupplied. These processes make important contributions to plant K+ homeostasis. A cDNA coding for a high-affinity K+ transporter, HKT1, was earlier cloned from wheat (Triticum aestivum L.) roots and functionally characterized. We demonstrate here that in both barley (Hordeum vulgare L.) and wheat roots, a rapid and large up-regulation of HKT1 mRNA levels resulted when K+ was withdrawn from growth media. This effect was specific for K+; withholding N caused a modest reduction of HKT1 mRNA levels. Up-regulation of HKT1 transcript levels in barley roots occurred within 4 h of removing K+, which corresponds to the documented increase of high-affinity K+ uptake in roots following removal of K+. Increased expression of HKT1 mRNA was evident before a decline in total root K+ concentration could be detected. Resupply of 1 mM K+ was sufficient to strongly reduce HKT1 transcript levels. In wheat root cortical cells, both membrane depolarizations in response to 100 micromolar K+, Cs+, and Rb+, and high-affinity K+ uptake were enhanced by K+ deprivation. Thus, in both plant systems the observed physiological changes associated with manipulating external K+ supply were correlated with levels of HKT1 mRNA expression. Implications of these findings for K+ sensing and regulation of the HKT1 mRNA levels in plant roots are discussed.
External Databases
Pubmed: 9765551
Keyword
cesium
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GrainGenes is a product of the Agricultural Research Service of the US Department of Agriculture.
GrainGenes Reference Report: PPS-118-651
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GrainGenes is a product of the Agricultural Research Service of the US Department of Agriculture. | |||