AUTHOR=Irulappan Vadivelmurugan , Park Hyun Woo , Han Sang-Yun , Kim Myung-Hee , Kim Jung Sun 

TITLE=Genome-wide identification of a novel Na+ transporter from Bienertia sinuspersici and overexpression of BsHKT1;2 improved salt tolerance in Brassica rapa

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1302315

DOI=10.3389/fpls.2023.1302315

ISSN=1664-462X

ABSTRACT=<p>Salt stress is an ever-increasing stressor that affects both plants and humans. Therefore, developing strategies to limit the undesirable effects of salt stress is essential. Sodium ion exclusion is well known for its efficient salt-tolerance mechanism. The High-affinity K<sup>+</sup> Transporter (HKT) excludes excess Na<sup>+</sup> from the transpiration stream. This study identified and characterized the HKT protein family in <italic>Bienertia sinuspersici</italic>, a single-cell C<sub>4</sub> plant. The <italic>HKT</italic> and <italic>Salt Overly Sensitive 1 (SOS1)</italic> expression levels were examined in <italic>B. sinuspersici</italic> and <italic>Arabidopsis thaliana</italic> leaves under four different salt stress conditions: 0, 100, 200, and 300 mM NaCl. Furthermore, <italic>BsHKT1;2</italic> was cloned, thereby producing stable transgenic <italic>Brassica rapa</italic>. Our results showed that, compared to <italic>A. thaliana</italic> as a glycophyte, the HKT family is expanded in <italic>B. sinuspersici</italic> as a halophyte with three paralogs. The phylogenetic analysis revealed three paralogs belonging to the HKT subfamily I. Out of three copies, the expression of <italic>BsHKT1;2</italic> was higher in <italic>Bienertia</italic> under control and salt stress conditions than in <italic>A. thaliana</italic>. Stable transgenic plants overexpressing <italic>35S::BsHKT1;2</italic> showed higher salt tolerance than non-transgenic plants. Higher biomass and longer roots were observed in the transgenic plants under salt stress than in non-transgenic plants. This study demonstrates the evolutionary and functional differences in HKT proteins between glycophytes and halophytes and associates the role of <italic>BsHKT1;2</italic> in imparting salt tolerance and productivity.</p>