@Article{phyton.2025.073959,
AUTHOR = {Shahin Imran, Maki Katsuhara},
TITLE = {Survey of Barley Sodium Transporter <i>HvHKT1;1</i> Variants and Their Functional Analysis},
JOURNAL = {Phyton-International Journal of Experimental Botany},
VOLUME = {94},
YEAR = {2025},
NUMBER = {11},
PAGES = {3653--3665},
URL = {http://www.techscience.com/phyton/v94n11/64709},
ISSN = {1851-5657},
ABSTRACT = {Barley (<i>Hordeum vulgare</i> L.) employs the Na<sup>+</sup> transporter <i>HvHKT1;1</i>, which is an N<sup>+</sup>-selective transporter. This study characterized the full-length <i>HvHKT1;1</i> (<i>HvHKT1;1-FL</i>) and three mRNA variants (<i>HvHKT1;1-V1</i>, <i>-V2</i>, and <i>-V3</i>), which encode polypeptides of 64.7, 54.0, 40.5, and 32.9 kDa, respectively. Tissue-specific expression profiling revealed that <i>HvHKT1;1-FL</i> is the most abundant transcript across leaf, sheath, and root tissues under normal conditions, with the highest expression in leaves. Under 150 mM NaCl stress, <i>HvHKT1;1-FL</i> and its variants showed a dynamic, time-dependent expression pattern, with peak leaf expression at 2 h, sheath expression at 12 h, and root expression at 2 h, suggesting their roles in early stress response. Functional analysis using two-electrode voltage-clamp measurements demonstrated that HvHKT1;1-FL is highly selective for Na<sup>+</sup>, with minimal conductance for K<sup>+</sup>, Li<sup>+</sup>, Rb<sup>+</sup>, or Cs<sup>+</sup>. It demonstrated high Na<sup>+</sup> transport efficiency, characterized by higher <i>V</i>max and lower <i>K</i>m values, while the variants showed reduced Na<sup>+</sup> currents, lower <i>V</i>max, and higher <i>K</i>m values, indicating decreased Na<sup>+</sup> transport capacity. Reversal potential analyses further confirmed Na<sup>+</sup> selectivity, with HvHKT1;1-FL displaying the strongest preference for Na<sup>+</sup>. Notably, while all variants retained Na<sup>+</sup> selectivity, they showed reduced efficiency, as indicated by a more negative reversal potential in low Na<sup>+</sup> conditions. These findings highlight the functional diversity among <i>HvHKT1;1</i> variants, with <i>HvHKT1;1-FL</i> playing a dominant role in Na<sup>+</sup> transport. The tissue-specific regulation of these variants under salinity stress underscores their importance in barley’s adaptive responses.},
DOI = {10.32604/phyton.2025.073959}
}