Mechanism study of jasmonic acid and salicylic acid enhances the cabbage black rot resistance by improving oxidative clearance capacity and synthesis of secondary metabolites

Black rot caused by Xanthomonas campestris pv. campestris ( Xcc ) poses a serious threat to cabbage production. Jasmonic acid (JA) and salicylic acid (SA), as important plant defense hormones, are widely involved in the disease resistance process of plants. However, the mechanism of JA and SA enhance resistance to Xcc remains unclear. In this study, by physiological and biochemical analyses, we concluded that both exogenous SA and JA alone treatments could significantly alleviate the inhibitory effect of Xcc on cabbage seedlings by regulating endogenous hormones, reactive oxygen species scavenging capacity, cell membrane stability, and promoting the accumulation of secondary metabolites. Among them, the treatment effect of SA alone was the best, followed by JA. However, the combined treatment of JA and SA did not show a synergistic effect, suggesting that the application of SA or JA alone might be more effective in disease prevention and control strategies. Our research results provide theoretical basis and data support for the green prevention and control of black rot.