Soybean Na+/H+ antiporter GmsSOS1 enhances antioxidant enzyme activity and reduces Na+ accumulation in Arabidopsis and yeast cells under salt stress

Abstract

Our previous work revealed that the soybean GmsSOS1 enhances salt tolerance in Arabidopsis. In this work, we studied the physiological mechanisms by which the GmsSOS1 confers salt and oxidative stress tolerance in Arabidopsis and yeast cells. Under salt stress condition, the GmsSOS1-expressing Arabidopsis plants displayed larger leaf area, lower leaf relative electrolytic leakage, less accumulation of H2O2, superoxide anion radicals (O2−), and malondialdehyde compared with wild type. In consistent with these observations, the activities of antioxidant enzymes catalase, ascorbate peroxide, and peroxidase in the GmsSOS1-expressing plants were higher than those in wild type under salt stress. Combined salt and oxidative stresses caused more damage and higher accumulation of H2O2 and Na+ than single stress condition in both wild type and the GmsSOS1-expressing plants. However, the GmsSOS1-expressing Arabidopsis plants could maintain significantly lower levels of H2O2 and Na+ and exhibited better growth than wild type under either single or combined stress. The GmsSOS1 complemented the yeast plasma membrane-localized Na+/H+ antiporter and enhanced salt tolerance by reducing Na+ accumulation in yeast cells. Our results suggest that the soybean GmsSOS1 can alleviate the primary Na+ toxicity by limiting Na+ accumulation and mitigate the secondary oxidative stress through improving antioxidant enzyme activity.