GsCLC-c2 from wild soybean confers chloride/salt tolerance to transgenic Arabidopsis and soybean composite plants by regulating anion homeostasis.

The responses of the GsCLC-c2 gene and its promoter to NaCl stress, as well as the Cl /salt tolerance of GsCLC-c2-transgenic Arabidopsis and overexpressed or RNAi wild soybean hairy root composite plants, were investigated. Results showed that both GsCLC-c2 and its promoter display enhanced induction under salt stress. In the transgenic Arabidopsis WT-GsCLC-c2 and atclc-c-GsCLC-c2 seedlings, the salt-induced growth reduction was markedly ameliorated; plant fresh weight, leaf area, and relative water content (RWC) increased; relative electrolytic leakage (REL), and malondialdehyde (MDA) content in shoots decreased significantly. In addition, accumulation of Cl and K , especially Cl , increased markedly in roots to minimize Cl transport to shoots and maintain higher and lower Cl /NO ratios in roots and shoots, respectively. When compared to GsCLC-c2-RNAi wild soybean composite plants under salt stress, clear advantages, such as growth appearance, plant height, and leaf area, were displayed by GsCLC-c2-overexpressing composite plants. Moreover, their REL values in roots and leaves declined significantly. The accumulation of absorbed Cl and Na in the roots increased, as the transportation to the stems and leaves decreased, the NO content in roots, stems, and leaves significantly increased, and the changes in K contents were small, which resulted in the maintenance of a low Cl /NO ratio in all plant parts and low Na /K ratio in stems and leaves. Taken together, these results highlight the role of GsCLC-c2 in regulating anionic homeostasis in NaCl-stressed transgenic Arabidopsis and soybean composite plants to maintain lower Cl /NO ratios in shoots, thus conferring enhanced Cl /salt tolerance.