Cloning of flavonoid 3′,5′-hydroxylase and 3′-hydroxylase homologs from black currant ( Ribes nigrum ) and their differential expression at various fruit maturation stages

Flavonoid 3′-hydroxylase (F3′H) and 3′,5′-hydroxylase (F3′5′H) generate precursor molecules for the synthesis of cyanidin-based anthocyanins (red) and delphinidin-based anthocyanins (blue to purple) in Ribes nigrum L. (black currant). In this study, full-length 1780 and 1650-bp cDNA homologs of RnF3′5′H1 and RnF3′H1 from black currant were identified and cloned using a homologous cloning technique. Data revealed that Rn F3′5′H1 and RnF3′H1 are homologs that encode enzymes involved in anthocyanin synthesis from different plants, which phylogenetically cluster with the CYP75B and CYP75A families in the P450 superfamily, respectively. The enzymes encoded by these two genes also shared a high homology with flavonoid hydroxylases identified from other plants. Furthermore, RnF3′5′H1 and RnF3′H1 levels were upregulated during fruit maturation. RnF3′5′H1 levels were associated with both anthocyanin and soluble carbohydrate levels in blackcurrant, while RnF3′H1 expression did not have such an association. The structure and expression patterns of RnF3′5′H1 and RnF3′H1 in blackcurrant were also characterized. Further studies should aid understanding of anthocyanin biosynthesis in black currant to develop molecular approaches and manipulate anthocyanin production in blackcurrant.