Document Type

Article

Publication Date

3-1-2012

Abstract

Cellular Na +/K + ratio is a crucial parameter determining plant salinity stress resistance. We tested the function of plasma membrane Na +/K + cotransporters in the High-affinity K + Transporter (HKT) family from the halophytic Arabidopsis (Arabidopsis thaliana) relative Thellungiella salsuginea. T. salsuginea contains at least two HKT genes. TsHKT1;1 is expressed at very low levels, while the abundant TsHKT1;2 is transcriptionally strongly up-regulated by salt stress. TsHKT-based RNA interference in T. salsuginea resulted in Na + sensitivity and K + deficiency. The athkt1 mutant lines overexpressing TsHKT1;2 proved less sensitive to Na + and showed less K + deficiency than lines overexpressing AtHKT1. TsHKT1;2 ectopically expressed in yeast mutants lacking Na + or K + transporters revealed strong K + transporter activity and selectivity for K + over Na +. Altering two amino acid residues in TsHKT1;2 to mimic the AtHKT1 sequence resulted in enhanced sodium uptake and loss of the TsHKT1;2 intrinsic K + transporter activity. We consider the maintenance of K + uptake through TsHKT1;2 under salt stress an important component supporting the halophytic lifestyle of T. salsuginea. © 2012 American Society of Plant Biologists.

Publication Source (Journal or Book title)

Plant Physiology

First Page

1463

Last Page

1474

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