Genome-Wide Analysis of Cation/Proton Antiporter Family in Soybean () and Functional Analysis of GmCHX20a on Salt Response.

Monovalent cation proton antiporters (CPAs) play crucial roles in ion and pH homeostasis, which is essential for plant development and environmental adaptation, including salt tolerance. Here, 68 CPA genes were identified in soybean, phylogenetically dividing into 11 Na/H exchangers (NHXs), 12 K efflux antiporters (KEAs), and 45 cation/H exchangers (CHXs). The genes are unevenly distributed across the 20 chromosomes and might expand largely due to segmental duplication in soybean. The GmCPA family underwent purifying selection rather than neutral or positive selections. The -element analysis and the publicly available transcriptome data indicated that GmCPAs are involved in development and various environmental adaptations, especially for salt tolerance. Based on the RNA-seq data, twelve of the chosen genes were confirmed for their differentially expression under salt or osmotic stresses using qRT-PCR. Among them, was selected due to its high induction under salt stress for the exploration of its biological function on salt responses by ectopic expressing in . The results suggest that the overexpression of increases the sensitivity to salt stress by altering the redox system. Overall, this study provides comprehensive insights into the CPA family in soybean and has the potential to supply new candidate genes to develop salt-tolerant soybean varieties.