VvERF17 mediates chlorophyll degradation by transcriptional activation of chlorophyll catabolic genes in grape berry skin

Chlorophylls in the skin contribute to grape (Vitis vinifera) berry color and quality. Degradation of chlorophyll occurs during berry development in grape, but less is known about the molecular mechanisms of this process. Here, we characterized an ethylene response factor, VvERF17, as a putative regulator of chlorophyll degradation in grape berry. VvERF17 expression was strongly correlates with development-induced and ETH-triggered chlorophyll degradation. Transient overexpression of VvERF17 in tobacco leaves, tomato fruits, and grape leaves led to color break and chlorophyll degradation, which were resulted from the upregulated expression of chlorophyll catabolic genes (CCGs), including Chlorophyll-b-reductase (NOL), pheophytinase (PPH), pheophorbide a oxygenase (PAO), and red Chlorophyll catabolite reductase (RCCR). Inversely, silencing of VvERF17 in grape leaves partially suppressed the expression of CCGs' expression. Major CCGs' expression was closely related to chlorophyll degradation and VvERF17 expression. It was further demonstrated that VvERF17 could activate the expression of major CCGs by directly binding to the ERF binding sites in their promoters. We conclude that VvERF17 mediates chlorophyll degradation by transcriptional activation of NOL, PPH, PAO, and RCCR. These findings elucidate the regulation mechanisms of chlorophyll degradation in grape and enrich our understanding of grape berry color formation.

Automated summary

The study revealed that VvERF17 plays a crucial role in chlorophyll degradation in grape berries by activating the expression of chlorophyll catabolic genes. These findings enhance our understanding of the mechanisms involved in grape berry color formation.