Characterization of the Na+-preferential transporter HKT1.1 from halophyte shrub Salix linearistipularis.

Abstract

Soil salinity is one of the main environmental limiting factors for plant growth and production. Sodium salt (NaCl) is the main salt in saline soils. The high-affinity K⁺ transporter (HKT1) is a Na⁺-preferential transporter identified in multiple glycophyte plants, and it participates in salt tolerance through shoot Na⁺ extrusion. However, there has been limited research on the identification and characterization of HKT1 from halophytes. In this study, SlHKT1.1 was cloned and functionally characterized from the halophytic shrub Salix linearistipularis. Sequence analysis revealed that SlHKT1.1 is a member of HKT1. Transient expression of SlHKT1.1 in tobacco leaves showed that it as a plasma membrane protein. Under NaCl and KCl stress, SlHKT1.1 overexpression severely inhibited the root growth of transgenic poplar seedlings. Ion content measurements revealed significantly higher Na⁺ content in the roots of transgenic poplar seedlings than in wild-type roots. Correlation analysis showed that significant root growth inhibition was associated with higher Na⁺ accumulation in roots in transgenic poplar seedlings. Analyses of K⁺ content and flux rate revealed that SlHKT1.1 was not directly involved in the transport and accumulation of K⁺. These studies suggest that SlHKT1.1, a plasma membrane Na⁺-preferential transporter from S. linearistipularis, can be used for enhancing plant salt tolerance via tissue- or cell-specific expression.

Supplementary information: The online version contains supplementary material available at 10.1007/s12298-025-01605-2.