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Type: Journal article
Title: High affinity Na⁺ transport by wheat HKT1;5 is blocked by K⁺
Other Titles: High affinity Na(+) transport by wheat HKT1;5 is blocked by K(+)
Author: Xu, B.
Hrmova, M.
Gilliham, M.
Citation: Plant Direct, 2020; 4(10):1-10
Publisher: Wiley
Issue Date: 2020
ISSN: 2475-4455
Statement of
Bo Xu, Maria Hrmova, Matthew Gilliham
Abstract: The wheat sodium transporters TmHKT1;5-A and TaHKT1;5-D are encoded by genes underlying the major shoot Na+ exclusion loci Nax2 and Kna1 from Triticum monococcum (Tm) and Triticum aestivum (Ta), respectively. In contrast to HKT2 transporters that have been shown to exhibit high affinity K+-dependent Na+ transport, HKT1 proteins have, with one exception, only been shown to catalyze low affinity Na+ transport and no K+ transport. Here, using heterologous expression in Xenopus laevis oocytes we uncover a novel property of HKT1 proteins, that both TmHKT1;5-A and TaHKT1;5-D encode dual (high and low) affinity Na+-transporters with the high-affinity component being abolished when external K+ is in excess of external Na+. Threedimensional structural modeling suggested that, compared to Na+, K+ is bound more tightly in the selectivity filter region by means of additional van der Waals forces, which is likely to explain the K+ block at the molecular level. The low-affinity component for Na+ transport of TmHKT1;5-A had a lower Km than that of TaHKT1;5-D and was less sensitive to external K+. We propose that these properties contribute towards the improvements in shoot Na+-exclusion and crop plant salt tolerance following the introgression of TmHKT1;5-A into diverse wheat backgrounds.
Keywords: Salinity; high-affinityK transporters; membrane transport; KtrB; dual sffinity; sodium exclusion
Rights: © 2020 The Authors. Plant Direct published by American Society of Plant Biologists and the Society for Experimental Biology and John Wiley & Sons Ltd. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
RMID: 1000028094
DOI: 10.1002/pld3.275
Grant ID:
Appears in Collections:Agriculture, Food and Wine publications

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