Overexpressing the N‐terminus of CATALASE2 enhances plant jasmonic acid biosynthesis and resistance to necrotrophic pathogen Botrytis cinerea B05.10

Salicylic acid (SA) acts antagonistically to jasmonic acid (JA) in plant immunity. We previously reported that CATALASE2 (CAT2) promotes JA‐biosynthetic acyl‐CoA oxidase (ACX) activity to enhance plant resistance to necrotrophic Botrytis cinerea, and SA represses JA biosynthesis through inhibiting CAT2 activity, while the underlying mechanism remains to be further elucidated. Here, we report that the truncated CAT2 N‐terminus (CAT2‐N) interacts with and promotes ACX2/3, and CAT2‐N‐overexpressing plants have increased JA accumulation and enhanced resistance to B. cinerea B05.10, but compromised antagonism of SA on JA. Catalase inhibitor treatment or mutating CAT2 active amino acids abolished CAT2 H(2)O(2)‐decomposing activity but did not affect its promotion of ACX2/3 activity via interaction. CAT2‐N, a truncated protein with no catalase activity, interacted with and promoted ACX2/3. Overexpressing CAT2‐N in Arabidopsis plants resulted in increased ACX activity, higher JA accumulation, and stronger resistance to B. cinerea B05.10 infection. Additionally, SA dramatically repressed JA biosynthesis and resistance to B. cinerea in the wild type but not in the CAT2‐N‐overexpressing plants. Together, our study reveals that CAT2‐N can be utilized as an accelerator for JA biosynthesis during plant resistance to B. cinerea B05.10, and this truncated protein partly relieves SA repression of JA biosynthesis in plant defence responses.