Analysis and verification of the conserved MYB binding element in the DFR promoter in Compositae

Abstract

Anthocyanins are ubiquitous in Compositae and MYB regulates the expression of DFR and plays an important role in anthocyanin synthesis. Here, the regulation pathway that MYB protein of subgroup 6 in Compositae promotes dihydroflavonol reductase (DFR) expression was analyzed and verified by yeast one-hybrid experiment in Saussurea medusa. The results of the branch model and site model analysis revealed that MYB gene underwent purification selection, and the motif of bHLH protein [DE]Lx(2)[RK]x(3)Lx(6)Lx(3))R and anthocyanin-related motif ANDV underwent strong purification selection during evolution. DFR promoter analysis showed that there are MYB binding site (GAGTTGAATGG) and bHLH binding site (CANNTG) at the sense strand of 84–116 nucleotide residues from the start codon, and the two motifs are separated by 9–10 nucleotide residues, and this rule exists in DFR promoters of many Compositae plants. Yeast one-hybrid experiment proved that SmMYB1 can activate the promoter of SmDFR. Our results provide a reference for further functional studyof DFR gene in Compositae.