Overexpression of KvCHX Enhances Salt Tolerance in Arabidopsis thaliana Seedlings

The CHX (cation/H+ exchanger) family plays an important role in the transmembrane transport of cation/H+ in plants. The aim of this study was to identify and functionally analyze the KvCHX gene in the halophyte Kosteletzkya virginica to investigate its role in regulating the K+/Na+ ratio under salinity tolerance. Based on a partial gene sequence of EST from K. virginica, the full-length DNA sequence of the KvCHX gene was obtained using genome walking technology. Structural analysis and phylogenetic relationship analysis showed that the KvCHX gene was closely related to the AtCHX17 gene. The KvCHX overexpression vector was successfully constructed and transformed into Arabidopsis via floral dipping. Arabidopsis seedlings overexpressing KvCHX showed an enhanced tolerance to salt stress compared with wild-type plants. Transgenic Arabidopsis seedlings grew better under K+ deficiency than WT. The results showed that KvCHX could promote the uptake of K+, increase the ratio of K+/Na+, and promote the growth of plants under K+ deficiency and treatment with NaCl solution. KvCHX is involved in K+ transport and improves plant salt tolerance by coordinating K+ acquisition and homeostasis.