NAC047/052/104 Synergistically Regulate the Dark-Induced Leaf Senescence in Non-Heading Chinese Cabbage

Non-heading Chinese cabbage (NHCC) is an important vegetable, and its leaves are harvested for consumption. Thus, the initiation and progression of leaf senescence in NHCC directly impact its yield and quality. In multiple plant species, NAC transcription factors are known to act as critical regulators of leaf senescence. However, in NHCC, the NAC transcription factors contributing to leaf senescence regulation remain to be identified, and the mechanisms underlying dark-induced leaf senescence remain unclear. To explore the molecular mechanisms of leaf senescence in NHCC, we stored NHCC away from light and subsequently examined dark-induced transcriptional alterations via RNA sequencing. Interestingly, three NAC transcription factors, BrNAC047, BrNAC052, and BrNAC104, were found to be potently activated by darkness. Subsequently, the virus-induced gene silencing of BrNAC047, BrNAC052, and BrNAC104 demonstrated that these three NACs act as positive regulators of dark-induced leaf senescence in NHCC. Dual-luciferase assays further confirmed that BrNAC047, BrNAC052, and BrNAC104 directly activate the promoters of certain senescence-associated genes. This study uncovers the molecular signaling pathways governing dark-induced leaf senescence in NHCC, highlighting the role of three key regulators and offering valuable molecular targets for delaying leaf senescence in NHCC.