Identification and analysis of cytochrome P450 family provides insightsinto the biosynthesis of flavonoids in safflower

Safflower was widely used in oil-producing, dying and traditional medicine. Favonoids were the main metabolite in safflower and high content flavonoids expecially C-glucosylquinochalcones including Hydroxysafflor yellow A, exert key role on protect cardiovascular. The cytochrome P450 play important role on plant growth and the biosynthesis of second metabolites including flavonoids etc. CYPs superfamily genes have been identified in many species, while, the specific CYPs family in safflower remains uncharacterized. In this study, 271 CtCYPs were identified in safflower genome and basic physical and chemical properties, the phylogenetic, gene structure, chromosomal localization, collinearity and tissue expression pattern were further analyzed. Results reveal the molecular weight of proteins ranged from 12.36-286.29 KDa and the amino acids sequence length was in the range of 109 to 2,496, 164 genes of the subcellular localization in chloroplasts. The 271 CtCYPs genes are separated into 31 different families attributing to 8 clans based on phylogenetic relationship and sequence similarity. A large number of tandem duplication events occur in CYP family genes, in particular, CYP706, CYP716, CYP71, CYP72, CYP76, CYP81, CYP82, CYP84, CYP89 and CYP92 families. Compared collinearity analysis unveil that CYP89 family genes are unique to safflower plants and the obvious expansion occur in C.tinctorius genome compared with other compositae plants. In addition, the expression patterns of 5 genesare closely related to flavonoid accumulation. These five genes have a C-glusesquinolone structure, and HSYA also has a C-glusesquinolone structure. In summary, the above 5 genes are key candidate genes involved in the HSYA biosynthesis pathway. Above findings lay a foundation for further research on the role of CtCYPs in breeding safflower varieties with enhanced HSYA in flowers.