TsHKT1;2, a HKT1 Homolog from the Extremophile Arabidopsis Relative Thellungiella salsuginea, Shows K⁺ Specificity in the Presence of NaC1

Publication Type:Journal Article
Year of Publication:2012
Authors:Ali, Z, PARK, HYEONGCHEOL, Ali, A, Oh, D-H, Aman, R, Kropornicka, A, HONG, HYEWON, Choi, W, Chung, WSik, Kim, W-Y, Bressan, RA, Bohnert, HJ, Lee, SYeol, Yun, D-J
Journal:Plant Physiology
Date Published:2012
ISBN Number:00320889

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 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 athktl 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 AtHKTl 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.

Short Title:Plant Physiology
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