A proposed model of the role of circadian Evening Complex in repressing jasmonate-induced leaf senescence.
Plants initiate leaf senescence to reallocate energy and nutrients from the aging to developing tissues for optimizing growth fitness and reproduction at the end of growing season or under stress. As an ubiquitous molecular time-keeping mechanism, circadian clock provides an adaptive advantage to higher plants by synchronizing internal growth behaviors with external daily changing environments. Jasmonate (JA), a lipid-derived phytohormone, is known as an important endogenous singal in inducing leaf senescence. However, whether and how circadian clock gates JA signaling to induce leaf senescence in plants remains elusive. A recent study by the research group in Institute of Botany, Chinese Academe of Sciences, led by Prof. Lei Wang, discovered that the Evening Complex (EC), a core component of circadian oscillator, negatively regulates leaf senescence in Arabidopsis thaliana.Their 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. They further 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 myc2myc3myc4 triple mutation. Collectively, their results reveal how the core component of circadian clock gates JA signaling to regulate leaf senescence.
This work has been published in Molecular Plant on January 2nd, 2018 as a research article. Assistant Prof. Yuanyuan Zhang is the leading author, and Prof. Lei Wang is the corresponding author of this article. This research was supported by the National Natural Sciences Foundation of China (31670290 and 31570292), Youth Innovation Promotion Association CAS to Y. Z. (NO. 2017110), ‘Youth 1000 plan’ to L.W. and the Chinese Academy of Sciences (QYZDB-SSW-SMC011 and XDTB0400-02).