Transcriptome Analysis of Key Genes Involved in Color Variation between Blue and White Flowers of Iris bulleyana

Figure 3

Schematic diagram of differential biosynthesis of pigmentation in Southwest iris where 3GT and 5GT downregulation shunted the anthocyanin pathways and resulted in white phenotype. Anthocyanin biosynthesis has been represented through a series of catalysts, including CHS (chalcone synthase), CHI (chalcone isomerase), F3H (flavanone-3-hydroxylase), F3H (flavonoid 3-hydroxylase), F35H (flavonoid 3,5-hydroxylase), DFR (dihydroflavonol 4-reductase), ANS (anthocyanidin synthase), 3GT (anthocyanin 3-O-glucosyltransferase), and 5GT (anthocyanin 5-O-glucosyltransferase). No significant differential expression was observed for the above-mentioned genes except for 3GT and 5GT, with downregulated expression pattern in white flowers resulting in the down-accumulation of 13 anthocyanins. No significant change in the carotenoid pathway explains the conserved yellow stripes in the flowers of both genotypes (PSY2 (phytoene synthase), PDS (phytoene desaturase), ZDS (Z-carotene desaturase), LCYB (lycopene β-cyclase), and CHYE (carotenoid ε-hydroxylase)). The genes colored in green exhibited normal expression between the two genotypes, while the genes colored in red were downregulated in the white variant. The blue box is the main anthocyanin synthesis process in the blue iris flower.