Jasmonic acid promotes leaf senescence through MYC2-mediated repression of CATALASE2 expression in Arabidopsis.

Plants relocate nutrients and energy from aging leaves to developing tissues during leaf senescence, which is important for plant growth, development, and responses to various environmental stimuli. Both jasmonic acid (JA) and H2O2 are two crucial signalling molecules positively regulating leaf senescence, whereas whether and how they are coordinated in leaf senescence remains elusive. Here, we report that H2O2 accumulates in JA-treated leaves, while scavenging the increased H2O2 can significantly suppresses JA-induced leaf senescence and the expression of senescence-associated genes (SAGs). The mutant myc2 with a mutation of MYC2, a master transcription factor in JA signalling pathway, exhibits delayed leaf senescence with increased catalase activity and decreased H2O2 accumulation compared with the wild type upon JA treatment. Further study showed that MYC2 downregulates CATALASE 2 (CAT2) expression by binding to its promoter, thus promoting JA-induced H2O2 accumulation and leaf senescence. Moreover, the delayed leaf senescence with reduced H2O2 accumulation and SAGs expression of the myc2 mutant is significantly reverted by the cat2-1 mutation in myc2 cat2-1 double mutant. Thus, our study reveals that JA represses CAT2 expression to increase H2O2 accumulation, thus promoting leaf senescence in a MYC2 dependent manner in Arabidopsis.