NAP is involved in GA-mediated chlorophyll degradation and leaf senescence by interacting with DELLAs in Arabidopsis.

KEY MESSAGE: RGA/GAI and NAP interacted with each other, and NAP was involved in GA signaling as a role of regulating age-dependent and dark-induced leaf senescence in Arabidopsis. Leaf senescence is a significant biological process which is beneficial for plant growth, development, and generation alternation in Arabidopsis. Recent researches have shown gibberellins (GAs) could accelerate leaf senescence. Nevertheless, the GA signaling involved in leaf senescence process remains elusive. Here, we reported a new potential regulation mechanism of GA-mediated chlorophyll degradation and leaf senescence. In this study, we confirmed that NAP positively regulated age-dependent and dark-induced leaf senescence and NAP knockout mutant nap was hyposensitive to GA3 (an active form of GA) treatment. DELLA family proteins with highly conserved structural domain function as master growth repressors that integrated GA signaling and leaf senescence. We validated RGA and GAI could interact with NAP in vitro and in vivo, and subsequently impaired the transcriptional activities of NAP to induce SAG113 and AAO3 expression in nap protoplasts. Taken together, we suggest that NAP is a novel component of the regulatory network that modulates the progress of leaf senescence in GA signaling.