Identification and Characterization of Rice OsHKT1;3 Variants.

Shahin Imran,Maki Katsuhara,Yoshiyuki Tsuchiya,Sen Thi Huong Tran

doi:10.3390/plants10102006

Abstract

In rice, the high-affinity K+ transporter, OsHKT1;3, functions as a Na+-selective transporter. mRNA variants of OsHKT1;3 have been reported previously, but their functions remain unknown. In this study, five OsHKT1;3 variants (V1-V5) were identified from japonica rice (Nipponbare) in addition to OsHKT1;3_FL. Absolute quantification qPCR analyses revealed that the transcript level of OsHKT1;3_FL was significantly higher than other variants in both the roots and shoots. Expression levels of OsHKT1;3_FL, and some variants, increased after 24 h of salt stress. Two electrode voltage clamp experiments in a heterologous expression system using Xenopus laevis oocytes revealed that oocytes expressing OsHKT1;3_FL and all of its variants exhibited smaller Na+ currents. The presented data, together with previous data, provide insights to understanding how OsHKT family members are involved in the mechanisms of ion homeostasis and salt tolerance in rice.

Highlights

Salinity is a dominant abiotic stress that decreases crop growth and productivity to a great extent [1,2,3,4]
Plant HKTs are divided into three classes: class 1 HKT proteins (HKT1s) function mainly as Na+-selective transporters, and they are present in both monocotyledonous and dicotyledonous plants; class 2 HKT proteins (HKT2s) function mainly as Na+-K+ symporters, and are present only in monocotyledonous plants; class 3 HKT proteins (HKT3s) are present in mosses and clubmosses, and their selectivity for Na+ and/or K+ is not yet clearly understood [14,15,16,17,18]
There is extensive evidence indicating the central role of HKT genes as Na+ and Na+/K+ transporters in controlling Na+ accumulation and salt tolerance in the halophytic turf grass, Sporobolus virginicus, as well as Arabidopsis thaliana, barley, soybeans, and rice [21,22,23,24,25,26,27]

Summary

Introduction

Salinity is a dominant abiotic stress that decreases crop growth and productivity to a great extent [1,2,3,4]. High-affinity potassium transporters (HKTs) are responsible for ion homeostasis and salt tolerance in plants [11,12,13]. There is extensive evidence indicating the central role of HKT genes as Na+ and Na+/K+ transporters in controlling Na+ accumulation and salt tolerance in the halophytic turf grass, Sporobolus virginicus, as well as Arabidopsis thaliana, barley, soybeans, and rice [21,22,23,24,25,26,27]. Seven functional HKT genes from rice have been identified.

Methods

Results

Conclusion