Cloning and expression analysis of Ficus carica anthocyanidin synthase 1 gene

Anthocyanidin synthase (ANS) is the key enzyme in anthocyanin biosynthesis. In this study, a full-length cDNA was cloned from fig (Ficus carica L.) syconia. Its open reading frame was 1077 base pairs (bp) long, encoding 358 amino acids. Multiple alignments revealed high amino acid sequence identity with ANS proteins from Morus alba (90% identity), Theobroma cacao (88% identity), and Vitis vinifera (86% identity). The gene was therefore designated FcANS1. Structural analysis showed that the FcANS1 protein might belong to the 2OG and Fe(II)-dependent oxygenase, containing binding sites for 2OG (H235, D237, H291) and Fe(II) (H301). Semi-quantitative RT-PCR analysis of FcANS1 transcript showed its expression in fig tree root tips, terminal buds, young leaves and young stems, but no expression in the mature stems, laminas or petioles. The patterns of FcANS1 expression and anthocyanin content were similar during syconia development: both were significantly upregulated during syconia maturation. FcANS1 expression was responsive to light, as bagging the syconia reduced FcANS1 expression and anthocyanin content in both fig skin and female flowers compared to natural light conditions. Our results lay the groundwork for further studies on anthocyanin accumulation and regulation in figs.