Molecular cloning and biochemical analysis of dihydroflavonol 4-reductase (DFR) from Brassica rapa ssp pekinesis (Chinese cabbage) using a heterologous system

Dihydroflavonol 4-reductase (DFR) is part of an important step in the flavonoid biosynthesis pathway of anthocyanins. We isolated the DFR gene from Brassica rapa ssp. pekinesis (Chinese cabbage), and found that biosynthesis of anthocyanins in tobacco could be modulated by introducing a heterologous DFRBra gene. RT-PCR showed that transgenic plants had abnormal flower colors compared with the wild-type controls, a response that was correlated with the level of DFR∧Bra transcription. HPLC analysis revealed that the isolated DFR∧Bra cDNA mainly produced cyanidin as well as a small amount of pelargonidin in the anthocyanin biosynthesis pathway of those tobacco plants.