Changes in Expression Level of OsHKT1;5 Alters Activity of Membrane Transporters Involved in K + and Ca 2+ Acquisition and Homeostasis in Salinized Rice Roots

• Published in: International journal of molecular sciences 2020-07, Vol.21 (14)
• Main Authors: Al Nayef, Mohammad, Solis, Celymar, Shabala, Lana, Ogura, Takaaki, Chen, Zhonghua, Bose, Jayakumar, Maathuis, Frans J M, Venkataraman, Gayatri, Tanoi, Keitaro, Yu, Min, Zhou, Meixue, Horie, Tomoaki, Shabala, Sergey
• Format: Article
• Language: English
• Subjects: Cation Transport Proteins - genetics; Gene Expression Regulation, Plant - genetics; Genes, Plant - genetics; Homeostasis - genetics; Homeostasis - physiology; Membrane Transport Proteins - genetics; Mesophyll Cells - metabolism; Mesophyll Cells - physiology; Oryza - genetics; Oryza - metabolism; Phenotype; Plant Proteins - genetics; Plant Roots - genetics; Plant Roots - metabolism; Plant Roots - physiology; Plant Shoots - genetics; Plant Shoots - metabolism; Plant Shoots - physiology; Potassium - metabolism; Salt Tolerance - genetics; Salt Tolerance - physiology; Salt-Tolerant Plants - genetics; Salt-Tolerant Plants - metabolism; Salt-Tolerant Plants - physiology; Sodium - metabolism; Stress, Physiological - genetics; Symporters - genetics; Xylem - genetics; Xylem - metabolism; Xylem - physiology
• ISSN: 1422-0067
• DOI: 10.3390/ijms21144882

In rice, the ; gene has been reported to be a critical determinant of salt tolerance. This gene is harbored by the 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 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( ) plants. Our data showed that Na reabsorption was observed in WT, but not NIL( ) 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 ; altered the activity of membrane transporters involved in K and Ca 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.