VvERF95 regulates chlorophyll degradation by transcriptional activation of VvPAO1 causing grape rachis degreening after harvesting

Abstract

• Ethylene plays important role during rachis degreening, expression of VvERF95 can be induced by ethylene. • VvERF95 upregulate VvPAO1 expression by binding to DRE cis -element in its promoter. • Transgenic plants of VvERF95 have lower chlorophyll content and transcript level of VvPAO1 and the other CCGs were increased. Rachis degreening is one of the main problems during postharvest storage of grape, its regulatory mechanism remains obscure. Here, we found that production of ethylene was increased and chlorophyll content was decreased during rachis degreening of Shine Muscat grape, while the reverse were observed after 1-MCP (1-methylcyclopropene) treatment. The ethylene transcription factor VvERF95 was isolated, and its transcriptional changes were closely correlated with chlorophyll content during rachis browning. The expression of VvERF95 was induced by ethylene and inhibited by 1-MCP. Dual-luciferase, yeast one-hybrid and EMSA assays, as well as motif mutation experiments, indicated that VvERF95 can bind to the promoter of pheophorbide a oxygenase ( VvPAO1 ) and upregulate its transcript levels. Overexpression of VvERF95 in grape lead to chlorophyll degradation in grape leaves, and increases in the transcript levels of VvPAO1 and most genes in the chlorophyll degradation pathway. Collectively, our findings decipher the mechanism of ethylene-enhanced chlorophyll degradation in grape, and will be useful for manipulating chlorophyll accumulation in grape and other plants.