Genome-wide identification and expression analysis of the cytochrome P450 gene family and their roles in phenylpropanoid and flavonoid biosynthesis of common buckwheat ‘QZZTQ’

Phenylpropanoids, including flavonoids, and other active components have risen in interest due to their important medicinal and edible value. The common buckwheat ‘QZZTQ’, a direct derivative of the red-flowered common buckwheat ‘HHTQ’, is highly enriched in flavonoids. Cytochrome P450 gene family plays an important role in plant metabolites, but its roles in the biosynthesis of phenylpropanoid and flavonoid in ‘QZZTQ’ are unclear. Our analysis identified 388 putative cytochrome P450 genes in common buckwheat ( Fagopyrum esculentum Moench.), referred to as FeP450s , with amino acid lengths of 68-2814 aa, molecular weights of 7.762-315.046 kDa, isoelectric points of 4.65-10.37. P450 genes were unevenly distributed on chromosomes, and the majority of genes were localized near the chromosome ends. The predicted subcellular localization results showed that FeP450s were distributed in a variety of organelles, especially in endoplasmic reticulum. Phylogenetic analysis divided FeP450s into 5 single-family clans and 4 multi-family clans, of which CYP71 clan contained the largest number of genes. 85 duplication events were identified, with 36 identified as tandem duplications. 15 motifs were identified in the FeP450 proteins. 60 genes belonging to CYP71 clan contained all the motifs. The promoter regions of FeP450s contained various cis -acting elements related to hormone, light and stress response, and 226 of them contained cis -acting elements involved in flavonoid biosynthesis. Comparative transcriptome analysis combined with Quantitative real-time PCR (qRT-PCR) suggested that 3 genes ( Fe2P450.20 , Fe7P450.25, and Fe8P450.11 ) might be key genes for the anthocyanin biosynthesis of red-flowered common buckwheat, the expression of which could be significantly induced by low temperature stress and 2 mM methyl jasmonate (MeJA) treatment, but suppressed by dark treatment. Coding-region variations combined rare c is-element divergency might serve as the primary factor driving differential anthocyanin accumulation between the white and red-flowered common buckwheat, which needs to be verified by experimental validation. These results revealed the wide involvement of FeP450 genes in the phenylpropanoid and flavonoid biosynthetic pathway, which would help elucidate the molecular mechanisms underlying anthocyanidin synthesis in red-flowered common buckwheat.