LcCOP1 and LcHY5 control the suppression and induction of anthocyanin accumulation in bagging and debagging litchi fruit pericarp

•LcUVR8-5 and LcHY5-1 were up-regulated after bag removal, while LcCOP1-2 was down-regulated.•LcCOP1-2 interacts with LcUVR8-5, LcHY5-1 and LcMYB1.•LcCOP1-2 negatively regulates anthocyanin accumulation.•LcHY5-1 directly bound to the promoters of anthocyanin biosynthesis genes and activated their expression. Bagging can improve fruit qualities and provide a useful method for studying fruit pigmentation. Bagging treatment regulates anthocyanin accumulation in the pericarp of litchi (Litchi chinensis Sonn.). However, how bagging treatment controls anthocyanin accumulation remains unclear. In this study, we analyzed the effects of bagging and debagging on the anthocyanin accumulation and its biosynthesis-related genes in litchi. To clarify the mechanism of light regulates anthocyanin biosynthesis, LcUVR8-5, LcCOP1-2 and LcHY5-1 genes in light signal transduction were identified. Gene expression analysis showed that LcUVR8-5 and LcHY5-1 were up-regulated after bag removal, while LcCOP1-2 was down-regulated. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that LcCOP1-2 interacts with LcUVR8-5, LcHY5-1 and LcMYB1. Moreover, LcCOP1-2 interacts with LcUVR8-5 in a light-dependent manner. Functional complementation of Arabidopsis cop1-4 mutant and transiently expressing experiments demonstrated that LcCOP1-2 negatively regulates anthocyanin accumulation. In addition, LcHY5-1 directly bound to the promoters of LcMYB1 and anthocyanin biosynthesis structural genes (LcCHS, LcCHI, LcF3H, and LcANS) and activated their expression. Taken together, our results preliminarily revealed that the light regulated anthocyanin biosynthesis in litchi through a relatively conserved UVR8-COP1-HY5 signal pathway.