Circadian Evening Complex Represses Jasmonate-Induced Leaf Senescence in Arabidopsis

Plants initiate leaf senescence to reallocate energy and nutrients from aging to developing tissues for optimizing growth fitness and reproduction at the end of the growing season or under stress. Jasmonate (JA), a lipid-derived phytohormone, is known as an important endogenous signal in inducing leaf senescence. However, whether and how the circadian clock gates JA signaling to induce leaf senescence in plants remains elusive. In this study, we show that Evening Complex (EC), a core component of the circadian oscillator, negatively regulates leaf senescence in Arabidopsis thaliana. Transcriptomic profiling analysis reveals that EC is closely involved in JA signaling and response, consistent with accelerated leaf senescence unanimously displayed by EC mutants upon JA induction. We found that EC directly binds the promoter of MYC2, which encodes a key activator of JA-induced leaf senescence, and represses its expression. Genetic analysis further demonstrated that the accelerated JA-induced leaf senescence in EC mutants is abrogated by myc2 myc3 myc4 triple mutation. Collectively, these results reveal a critical molecular mechanism illustrating how the core component of the circadian clock gates JA signaling to regulate leaf senescence.