AcWRKY22 activates AcMYB210 to regulate light induced anthocyanin accumulation in kiwifruit leaves

Abstract

Plant leaves often develop red coloration in response to aging and environmental changes. High light or continuous light treatments can elevate anthocyanins, which we observed in normally green kiwifruit leaves. The underlying mechanism in this response was investigated using transcriptomic analysis. Results revealed that multiple anthocyanin biosynthesis genes, particularly Flavonoid-3-O-glucosyltransferase ( AcF3GT1a ), ( AcF3GT4 ) can convert unstable anthocyanidins into stable colored anthocyanins, and glutathione-S-transferase ( AcGST1 ) is responsible for the safe delivery of anthocyanins from the endoplasmic reticulum to the vacuole, were significantly upregulated under continuous light light-stress treatments. AcMYB210 , a member of the S6 MYB subfamily in kiwifruit with previously unknown function, was specifically induced. Dual-luciferase, yeast one-hybrid, and homologous genetic transformation assays confirmed that AcMYB210 directly binds to and activates the promoters of anthocyanin pathway genes, thereby promoting anthocyanin accumulation in kiwifruit leaves. A light-induced transcription factor, AcWRKY22 , was found to directly bind and activate the AcMYB210 promoter. In addition, AcMYB210 was highly expressed in plants whose leaves turned red after waterlogging stress. In summary, our data reveal the critical role of the AcWRKY22-AcMYB210 module in mediating light signal regulation of anthocyanin biosynthesis in kiwifruit leaves, providing new insights into the regulation of kiwifruit anthocyanin biosynthesis by light signals.