Overexpression of Peroxidase Gene GsPRX9 Confers Salt Tolerance in Soybean

Abstract

Peroxidases play prominent roles in antioxidant responses and stress tolerance in plants; however, their functions in soybean tolerance to salt stress remain unclear. Here, we investigated the role of a peroxidase gene from the wild soybean (<i>Glycine soja</i>), <i>GsPRX9</i>, in soybean tolerance to salt stress. <i>GsPRX9</i> gene expression was induced by salt treatment in the roots of both salt-tolerant and -sensitive soybean varieties, and its relative expression level in the roots of salt-tolerant soybean varieties showed a significantly higher increase than in salt-sensitive varieties after NaCl treatment, suggesting its possible role in soybean response to salt stress. <i>GsPRX9</i>-overexpressing yeast (strains of INVSc1 and G19) grew better than the control under salt and H₂O₂ stress, and <i>GsPRX9</i>-overexpressing soybean composite plants showed higher shoot fresh weight and leaf relative water content than control plants after NaCl treatment. Moreover, the <i>GsPRX9</i>-overexpressing soybean hairy roots had higher root fresh weight, primary root length, activities of peroxidase and superoxide dismutase, and glutathione level, but lower H₂O₂ content than those in control roots under salt stress. These findings suggest that the overexpression of the <i>GsPRX9</i> gene enhanced the salt tolerance and antioxidant response in soybean. This study would provide new insights into the role of peroxidase in plant tolerance to salt stress.