Circadian Evening Complex Represses Jasmonate-Induced Leaf Senescence in Arabidopsis

Abstract

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.

Arabidopsis WRKY53, a Node of Multi-Layer Regulation in the Network of Senescence

“…In the last two decades, the plant circadian clock advanced from a simple timekeeper to a complex developmental manager [99] so that Sanchez and Kay already entitled the circadian clock as the "mastermind" of plant life. The evening complex (EC), which is a critical component of the core oscillator, coordinates environmental and endogenous signals [100] and represses jasmonate-induced leaf senescence [101]. In addition, CIRCADIAN CLOCK-ASSOCIATED1 regulates ROS homeostasis and oxidative stress responses through association with EC at promoters of ROS-responsive genes in vivo.…”

Temporal Control of Plant–Environment Interactions by the Circadian Clock

“…The EC acts to inhibit JA-induced leaf senescence by directly binding to the MYC2 promoter to repress expression. Mutants in EC genes have accelerated JA-mediated senescence, which is suppressed in myc2 mutants, as well as precocious leaf senescence phenotypes (Zhang et al, 2017). TIME FOR COFFEE (TIC), which interacts with the EC (Huang et al, 2016) also contributes to regulate MYC2.…”

The E3 Ubiquitin Ligase HAF1 Modulates Circadian Accumulation of EARLY FLOWERING3 to Control Heading Date in Rice under Long-Day Conditions

“…The N-terminal and middle domains of ELF3 participate in the interaction with COP1 and GI separately, which regulate the accumulation pattern of GI to shape its proper functioning in the control of circadian oscillation and photoperiodism (Yu et al, 2008). Additionally, the middle domain is involved in the formation of the ELF4-ELF3-LUX complex, which is required for circadian gating of hypocotyl growth in the evening and regulates leaf senescence by gating jasmonate signaling (Nusinow et al, 2011;Ezer et al, 2017;Zhang et al, 2018). The C-terminal domain of ELF3 does not appear to interact with any protein; it is essential for homodimer formation and for the localization of this protein in nuclear bodies (Liu et al, 2001;Herrero et al, 2012).…”