Changes in Expression Level of <i>OsHKT1;5</i> Alters Activity of Membrane Transporters Involved in K<sup>+</sup> and Ca<sup>2+</sup> Acquisition and Homeostasis in Salinized Rice Roots
In rice, the <i>OsHKT1;5</i> gene has been reported to be a critical determinant of salt tolerance. This gene is harbored by the <i>SKC1</i> locus, and its role was attributed to Na<sup>+</sup> unloading from the xylem. No direct evidence, however, was provided in...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-07-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/21/14/4882 |
| Summary: | In rice, the <i>OsHKT1;5</i> gene has been reported to be a critical determinant of salt tolerance. This gene is harbored by the <i>SKC1</i> locus, and its role was attributed to Na<sup>+</sup> unloading from the xylem. No direct evidence, however, was provided in previous studies. Also, the reported function of <i>SKC1</i> on the loading and delivery of K<sup>+</sup> to the shoot remains to be explained. In this work, we used an electrophysiological approach to compare the kinetics of Na<sup>+</sup> uptake by root xylem parenchyma cells using wild type (WT) and NIL(<i>SKC1</i>) plants. Our data showed that Na<sup>+</sup> reabsorption was observed in WT, but not NIL(<i>SKC1</i>) plants, thus questioning the functional role of <i>HKT1</i>;<i>5</i> as a transporter operating in the direct Na<sup>+</sup> removal from the xylem. Instead, changes in the expression level of <i>HKT1</i>;<i>5</i> altered the activity of membrane transporters involved in K<sup>+</sup> and Ca<sup>2+</sup> acquisition and homeostasis in the rice epidermis and stele, explaining the observed phenotype. We conclude that the role of <i>HKT1</i>;<i>5</i> in plant salinity tolerance cannot be attributed to merely reducing Na<sup>+</sup> 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. |
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| ISSN: | 1661-6596 1422-0067 |