CHARACTERIZATION OF A NEW DIHYDROFLAVONOL REDUCTASE/FLAVANONE REDUCTASE FROM MAIZE

MA. LORENA FALCONE FERREYRA; MA. ISABEL CASAS; ERICH GROTEWOLD; PAULA CASATI

Rosario

Congreso; L Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular; 2014

Dihydroflavonol reductase (DFR) activity, involved in anthocyanin biosynthesis, is widely distributed in higher plants. Flavanone reductase (FNR) activity, in contrast, has only been described in some species being implicated in 3-deoxyflavonoid biosynthesis. Maize A1 locus encodes a protein with DFR and FNR activities and is involved in anthocyanin and flavan-4-ol formation, the latter leading to brick-red phlobaphene formation in kernels. A1 mutants have brown colored kernels and they are not complemented by the A4 locus, a paralog of A1 on which information is limited, suggesting differential expression and regulation among these loci. The objective is to characterize A4 activity in maize. We demonstrate that both loci are activated by the transcription factors P1 and C1/R, regulating phlobaphene and anthocyanin accumulation, respectively. Also, both genes are regulated by UV-B radiation, showing higher transcript levels in leaves from high altitude landraces compared to inbred lines, suggesting that anthocyanin accumulation as another protection mechanism against UV-B radiation developed by these landraces. We isolated the A4 coding region and expressed it in E .coli for in vitro activity assays. Our results indicate that A4 has both DFR and FNR activities. We are now testing for its ability to complement Arabidopsis tt3 mutants to further analyze its function in planta.