Isolation and Functional Characterization of Multiple NADPH-Cytochrome P450 Reductase Genes from in View of Catechin Biosynthesis.

Catechins are critical constituents for the sensory quality and health-promoting benefits of tea. Cytochrome P450 monooxygenases are required for catechin biosynthesis and are dependent on NADPH-cytochrome P450 reductases (CPRs) to provide reducing equivalents for their activities. However, CPRs have not been identified in tea, and their relationship to catechin accumulation also remains unknown. Thus, three CPR genes were identified in this study, all of which had five CPR-related conserved domains and were targeted to the endoplasmic reticulum. These three recombinant CPR proteins could reduce cytochrome using NADPH as an electron donor. Heterologous co-expression in yeast demonstrated that all the three CPRs could support the enzyme activities of C4H and F3'H. Correlation analysis indicated that the expression level of 1 (or 2 or 3) was positively correlated with 3',4',5'-catechin (or total catechins) content. Our results indicate that the are involved in the biosynthesis of catechins in tea leaves.