Changes in Expression Level of OsHKT1;5 Alters Activity of Membrane Transporters Involved in K+ and Ca2+ Acquisition and Homeostasis in Salinized Rice Roots
Title | Changes in Expression Level of OsHKT1;5 Alters Activity of Membrane Transporters Involved in K+ and Ca2+ Acquisition and Homeostasis in Salinized Rice Roots |
Publication Type | Journal Article |
Year of Publication | 2020 |
Authors | Alnayef M, Solis C, Shabala L, Ogura T, Chen Z, Bose J, Maathuis FJM, Venkataraman G, Tanoi K, Yu M, Zhou M, Horie T, Shabala S |
Journal | International Journal of Molecular Sciences |
Volume | 21 |
Start Page | 1 |
Issue | 4882 |
End page | 13 |
Date Published | 07/2020 |
Type of Article | Journal |
Keywords | epidermis, GORK, HAK5, RBOHD, Salinity stress, SKC1, sodium; potassium, stele, Xylem loading |
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 KT1;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. |