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Abstract

In rice, the OsHKT1;5 gene has been reported to be a critical determinant of salt tolerance. This gene is harbored by the SKC1 locus, and its role was attributed to Na+ unloading from the xylem. No direct evidence, however, was provided in previous studies. Also, the reported function of SKC1 on the loading and delivery of K+ to the shoot remains to be explained. In this work, we used an electrophysiological approach to compare the kinetics of Na+ uptake by root xylem parenchyma cells using wild type (WT) and NIL(SKC1) plants. Our data showed that Na+ reabsorption was observed in WT, but not NIL(SKC1) plants, thus questioning the functional role of HKT1;5 as a transporter operating in the direct Na+ removal from the xylem. Instead, changes in the expression level of HKT1;5 altered the activity of membrane transporters involved in K+ and Ca2+ acquisition and homeostasis in the rice epidermis and stele, explaining the observed phenotype. We conclude that the role of HKT1;5 in plant salinity tolerance cannot be attributed to merely reducing Na+ concentration in the xylem sap but triggers a complex feedback regulation of activities of other transporters involved in the maintenance of plant ionic homeostasis and signaling under stress conditions.

Item Type:	Article
Authors/Creators:	Alnayef, M and Solis, C and Shabala, L and Ogura, T and Chen, Z and Bose, J and Maathuis, FJM and Venkataraman, G and Tanoi, K and Yu, M and Zhou, M and Horie, T and Shabala, S
Keywords:	rice roots, salinity, membrane transporters, OsHKT1;5, K+, Ca2+, salinity stress, xylem loading, sodium, potassium, SKC1, HAK5, GORK, RBOHD, epidermis, stele
Journal or Publication Title:	International Journal of Molecular Sciences
Publisher:	Molecular Diversity Preservation International
ISSN:	1422-0067
DOI / ID Number:	https://doi.org/10.3390/ijms21144882
Copyright Information:	Copyright 2020 The Author(s)Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0)https://creativecommons.org/licenses/by/4.0/
Related URLs:	Google Scholar: Shabala, L UTAS Profile: Shabala, L Google Scholar: Zhou, M UTAS Profile: Zhou, M Google Scholar: Shabala, S UTAS Profile: Shabala, S
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