Effects of Salicylic Acid on Growth, Physiology, and Gene Expression in Rice Seedlings under Salt and Drought Stress

Salt and drought stress has been an important factor limiting agricultural production, and SA is an important phenolic involved in stress response, but the function of SA in response to dual salt and drought stress in rice is not clear. In this study, the effects and mechanisms of exogenous SA-triggered in rice adaptation to dual salt and drought stress were investigated by detecting physiological and biochemical indexes and the expression of salt and drought tolerance genes. The results showed that the application of SA could significantly increase the antioxidant enzyme activities of rice seedlings under salt and drought stress, thereby reducing the contents of rice H2O2 and MDA and maintaining the growth of rice seedlings. Moreover, the expression of genes involved in the response of abiotic stress, such as OsDREB2A, OsSAPK8, OsSAPK10 and OsMYB2, were up-regulated under salt and drought treatment, and SA application could further enhance the expression of those genes like OsDREB2A and OsSAPK8, suggesting that SA might regulate antioxidant enzyme activity via inducing the expression of salt and drought tolerance genes and enhancing the salt and drought tolerance of rice. The results will enrich the knowledge of the function of SA and provide a reference for studying the mechanism of SA in the salt and drought resistance of rice, and breeding new rice germplasm with improved salt and drought resistance.