The wheat Rc gene for red coleoptile colour codes for a transcriptional activator of late anthocyanin biosynthesis genes

Genes that regulate anthocyanin pigmentation in wheat coleoptiles were investigated in three lines of wheat. When grown in the light, the wheat line Hope developed red coleoptiles, while another line, Chinese Spring (CS), expressed green coleoptiles. Another line CS(Hope7A), a chromosome substitution line that carries chromosome 7A of Hope in a CS background, also developed a red coleoptile. In the dark, none of the three lines developed colored coleoptiles. Anthocyanin biosynthesis pathway genes have been grouped into two subsets: early biosynthesis genes (EBGs), which include CHS, CHI and F3H, and late biosynthesis genes (LBGs), which include DFR, ANS and UFGT. None of these six genes was upregulated in coleoptiles grown in the dark, whereas all were activated by light in coleoptiles of Hope and CS(Hope7A). In coleoptiles of CS grown in the light, the EBGs were expressed, but the three LBGs were not. The Rc gene located on chromosome 7 appears to encode a transcription activator of LBGs involved in light-regulation of anthocyanin synthesis.