Light regulation of anthocyanin accumulation and chalcone synthase gene expression in petunia flowers

We have previously shown that light is essential for anthocyanin synthesis in detached petunia flowers. In this study, we examined the effect of light quality on anthocyanin accumulation and on the expression of the anthocyanin biosynthetic gene chalcone synthase (chs) in the attached petunia flowers. When plants were kept for 48 h in the dark, chs expression could not be detected. Blue light and red light promoted the expression of the gene to similar levels, whereas the effect of green light was slightly smaller. Neither UV-A nor UV-B radiation were required for anthocyanin accumulation, or for the induction and maintenance of chs expression. The results of this study show that light is essential for anthocyanin synthesis in petunia flowers and that its active spectrum includes most of the visible part but not UV radiation.