Overexpressing the wheat dihydroflavonol 4-reductase gene TaDFR increases anthocyanin accumulation in an Arabidopsis dfr mutant

Plants of wheat cultivar Iksan370, which was recently produced by crossing paternal line Keumkang with maternal line Xian83, accumulate anthocyanins in their coleoptiles and seeds. However, the spatio-temporal regulation of anthocyanin biosynthesis genes in wheat remains poorly understood. Therefore, in the present study, we characterized wheat dihydroflavonol 4-reductase (DFR), which catalyzes the conversion of dihydroflavonol to leucoanthocyanidins during anthocyanin biosynthesis, using a heterologous expression system. The deduced amino acid sequence from full-length cDNA of wheat DFR cloned from young seedlings of Iksan370 (TaDFR-I) includes a well-conserved substrate-binding domain compared with previously identified DFRs. Furthermore, as expected, phylogenetic tree analysis placed TaDFR-I in the monocotyledonous clade. Introduction of TaDFR-I into the wild-type Arabidopsis Col-0 and dfr mutant backgrounds resulted in significant accumulation of anthocyanins in the respective transgenic plants. Similarly, TaDFR transcripts highly accumulated in Iksan370 wheat seedlings under various anthocyanin-inducing conditions, including low temperature, high salt and sugar levels, and UV-B illumination. Thus, we functionally characterized TaDFR-I from Iksan370 lines using a heterologous expression system and revealed the presence of transcriptional regulatory factors similar to those of Arabidopsis that regulate TaDFR expression in response to various abiotic stresses.