Exogenously applied poly-γ-glutamic acid alleviates salt stress in wheat seedlings by modulating ion balance and the antioxidant system

Salt stress is a main abiotic stress that limits agricultural productivity in many parts of the world. To investigate whether poly-gamma-glutamic acid (gamma-PGA) can alleviate the negative effects of salt stress on wheat, a foliar application of 400 mg/L gamma-PGAwas applied to wheat seedlings, which were then subjected to 150 mM NaCl. Our results showed that after application of gamma-PGA, the plant height, the plant weight, and the antioxidant enzymes including superoxide dismutase, peroxidase, and catalase were significantly increased compared with the treatment of 150 mM NaCl alone. Meanwhile, gamma-PGA application also resulted in high accumulation of K+ and decreased storage of Na+ in wheat leaves. These results suggest that gamma-PGA treatment may improve salt tolerance of wheat by diminishing ionic imbalances and enhancing antioxidant capacity. Our results indicate that exogenous gamma-PGA could alleviate the damage caused by salt stress.