Abstract
Flavonoid 3',5'-hydroxylase (F3'5'H) and flavonoid 3'-hydroxylase (F3'H), cytochrome P450 enzymes, are the key enzymes for biosynthesis of delphinidin and cyanidin, respectively, and belong to CYP75A and CYP75B in the cytochrome P450 classification, respectively. CYP75A and CYP75B diverted before the speciation of seed plants. However, a recent report indicates that the F3'5'H in Asteraceae plants belong to CYP75B and that the F3'5'H gene was derived from the F3'H gene.
Antirrhinum majus produces pelargonidin and cyanidin but not delphinidin, and thus lack violet flower colour while A. kellogii generates delphinidin and violet colour. We isolated two CYP75A and one CYP75B cDNAs from the A. kellogii petal cDNA library. Their over-expression in petunia resulted in elevated amount of delphinidin and cyanidin based anthocyanins, respectively, and flower color alteration. The results indicate that A. kellogii CYP75A and CYP75B encode F3'5'H and F3'H, respectively, and that A. majus lost F3'5'H activity during its evolution.
