Expression of anthocyanin biosynthetic genes in ornamental bananas

One of the attractive tropical plants is ornamental bananas with colorful male inflorescence bracts. Anthocyanin components and combination within these bracts relate to the color variations that occur in the banana family, Musaceae. Anthocyanin biosynthesis of several pigments and genes has already been studied. However, the underlining genetic background which causes color differences has not been explained. In our study, to investigate the molecular genetic background of the color variations in bracts of the bananas, anthocyanin biosynthetic pathways in uncommon yellow and pale purple bract taxa were compared to that of other species with orange and red-purple bracts. Anthocyanin content and expression analysis of dihydroflavonol 4-reductase (DFR) and leucoanthocyanidin dioxygenase (LDOX) genes were analyzed. The results showed that the expression level of DFR and LDOX genes was almost absent in the orange-and-red-purple colored-deficient taxa, i.e., the yellow bract Musa rubra var. siamensis and the green bract Ensete glaucum. Thus, the results suggested these two genes positively are factors related to anthocyanin accumulation in the banana bracts.