A conserved primary salt tolerance mechanism mediated by HKT transporters: a mechanism for sodium exclusion and maintenance of high K+/Na+ ratio in leaves during salinity stress

Authors

  • FELIX HAUSER,

    1. Division of Biological Sciences, Cell and Developmental Biology Section, and Center for Molecular Genetics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0116, USA and
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  • TOMOAKI HORIE

    Corresponding author
    1. Group of Molecular and Functional Plant Biology, Research Institute for Bioresources, Okayama University, 20-1, Chuo-2-chome, Kurashiki, Okayama 710-0046, Japan
      T. Horie. Fax: +086 434 1249; e-mail: horie@rib.okayama-u.ac.jp
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  • This manuscript is part of the special issue on Drought & Salt Stress. There should be no charge for the colour figures.

T. Horie. Fax: +086 434 1249; e-mail: horie@rib.okayama-u.ac.jp

ABSTRACT

Increasing soil salinity is a serious threat to agricultural productions worldwide in the 21st century. Several essential Na+ transporters such as AtNHX1 and AtSOS1 function in Na+ tolerance under salinity stress in plants. Recently, evidence for a new primary salt tolerance mechanism has been reported, which is mediated by a class of HKT transporters both in dicots such as Arabidopsis and monocot crops such as rice and wheat. Here we present a review on vital physiological functions of HKT transporters including AtHKT1;1 and OsHKT1;5 in preventing shoot Na+ over-accumulation by mediating Na+ exclusion from xylem vessels in the presence of a large amount of Na+ thereby protecting leaves from salinity stress. Findings of the HKT2 transporter sub-family are also updated in this review. Subjects regarding function and regulation of HKT transporters, which need to be elucidated in future research, are discussed.

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