Transcriptomic Analysis of Ficus carica Peels with a Focus on the Key Genes for Anthocyanin Biosynthesis

Fig (Ficus carica L.), a deciduous fruit tree of the Moraceae, provides ingredients for human health such as anthocyanins. However, little information is available on its molecular structure. In this study, the fig peels in the yellow (Y) and red (R) stages were used for transcriptomic analyses. Comparing the R with the Y stage, we obtained 6224 differentially expressed genes, specifically, anthocyanin-related genes including five CHS, three CHI, three DFR, three ANS, two UFGT and seven R2R3-MYB genes. Furthermore, three anthocyanin biosynthetic genes, i.e., FcCHS1, FcCHI1 and FcDFR1, and two R2R3-MYB genes, i.e., FcMYB21 and FcMYB123, were cloned; sequences analysis and their molecular characteristics indicated their important roles in fig anthocyanin biosynthesis. Heterologous expression of FcMYB21 and FcMYB123 significantly promoted anthocyanin accumulation in both apple fruits and calli, further suggesting their regulatory roles in fig coloration. These findings provide novel insights into the molecular mechanisms behind fig anthocyanin biosynthesis and coloration, facilitating the genetic improvement of high-anthocyanin cultivars and other horticultural traits in fig fruits.