UV-B photoreceptor PavUVR8 mediates anthocyanin biosynthesis by directly activating PavMYB75L expression in sweet cherry fruits

Light is essential for the red coloration of blush sweet cherry fruits. Ultraviolet (UV) radiation enhances anthocyanin biosynthesis in sweet cherry fruits, but the underlying mechanism remains relatively unknown. In this study, PavUVR8, which is a UV-B photoreceptor, was identified and functionally characterized. Gene expression analyzes revealed that PavUVR8 is associated with fruit coloration. Subcellular localization results indicated that PavUVR8 is present in the cytoplasm and nucleus under light. Additionally, virus-induced silencing of PavUVR8 inhibited anthocyanin biosynthesis in sweet cherry fruits, whereas the overexpression of PavUVR8 in sweet cherry calli enhanced anthocyanin accumulation. Furthermore, yeast one-hybrid, chromatin immunoprecipitation followed by quantitative PCR, and dual-luciferase assays demonstrated that PavUVR8 can bind directly to the promoters of PavMYB75L, PavDFR , and PavANS to increase their expression levels. Collectively, our results revealed that PavUVR8–PavMYB75L forms a module that regulates anthocyanin biosynthesis, providing new insights into the regulatory effects of UV irradiation on anthocyanin accumulation in blush sweet cherry fruits.