Genome-wide identification of the pigment formation-regulating CYP450 family gives new insights into color improvement in Bougainvillea

• A total of 270 cytochrome P450 monooxygenase genes belonging to eight clans were identified in Bougainvillea . • Betalains and flavonoids are both correlated with bracts color parameter changes. • BbCYP40 and BbCYP220 genes may play important roles in betalains and flavonoids biosynthesis in Bougainvillea respectively. Bougainvillea is a popular ornamental plant, with modification of flower color is a primary breeding objective. Flower color can be attributed to three classes of pigment: flavonoids, carotenoids, and betalains. The cytochrome P450 monooxygenase gene family plays important roles in pigment biosynthesis. In Bougainvillea , although the CYPs involved in betalains biosynthesis has been reported, the CYPs related to flavonoids and carotenoids biosynthesis have not been characterized. Here, whole-genome analyzes identified 270 BbCYPs in Bougainvillea , which were divided into eight clans via phylogenetic analysis. By exploring the structure, physicochemical properties, chromosome localization and motif composition of BbCYPs, as well as evolutionary relationships with CYPs in other plants, we preliminarily screened 13 potential BbCYPs related to pigment biosynthesis. The expression levels of these genes except BbCYP1 , at different developmental stages showed an upward trend. Correlation analysis results indicated that betalains and flavonoids may play major roles in Bougainvillea × buttiana ‘Mrs Butt’ bracts color formation. Among 13 BbCYPs, the BbCYP40 and BbCYP220 genes exhibited the strongest correlation with betalains and flavonoids, respectively. BbCYP85 gene exhibited stronger correlation with carotenoids than BbCYP162 gene. These findings provide valuable genetic resources for improving Bougainvillea bract color.