Methyl salicylate and methyl jasmonate induce resistance to Alternaria tenuissima by regulating the phenylpropane metabolism pathway of winter jujube

The black rot disease of winter jujube causes considerable losses to the jujube industry in Xinjiang. Methyl salicylate (MeSA) and methyl jasmonate (MeJA) are elicitors of plant disease resistance; therefore, the inhibitory effects of 1 mmol/L MeSA and 0.1 mmol/L MeJA on the black rot disease of winter jujube caused by Alternaria tenuissima were investigated herein. Both MeSA and MeJA reduced the fruit decay index, and the effect of MeJA was superior. MeSA and MeJA enhanced the activities of enzymes related to phenylpropane metabolism and pathogenesis-related proteins, and the expression of their corresponding genes. MeSA and MeJA increased the accumulation of phenylpropane metabolites, containing the lignin, total phenol, and total flavonoid contents. These findings indicated that MeSA and MeJA may enhance the resistance of winter jujube to A. tenuissima by enhancing the phenylpropane metabolism pathway and the activity of pathogenesis-related proteins.