CsHY5 Regulates Light-Induced Anthocyanin Accumulation in Camellia sinensis

Tea is one of the world's major non-alcoholic beverages, popular for its health benefits and flavor. Purple-bud tea is particularly rich in anthocyanins, the concentration of which varies depending on the tea cultivar and cultivation conditions. While the genetic regulation of anthocyanin accumulation is well understood, the impact of environmental factors, such as light, on anthocyanin synthesis is less documented. In this study, we analyzed the anthocyanin content and the expression levels of anthocyanin biosynthesis genes (ABGs), CsAN1, and CsHY5, under different light intensities and durations. The expression of both CsAN1 and ABGs was significantly induced by light, with an intensity of 8000 lx particularly effective in promoting anthocyanin accumulation. Furthermore, we explored the effect of shading on anthocyanin content, finding that fifty percent shading reduced anthocyanin content by nearly half. Finally, dual-luciferase reporter assays and yeast one-hybrid assays confirmed the direct regulation of CsHY5 on CsAN1. These findings offer insights into the regulatory mechanisms underlying light-induced anthocyanin biosynthesis in tea plants and suggest a potential method for controlling anthocyanin accumulation in tea production.