R2R3 MYB Transcription Factors Involved in Flower Petal Pigmentation via Regulating Anthocyanin Synthesis in Rhododendron simsii.

Azaleas (Rhododendron simsii) are popular ornamental woody plants known for their bright colors; however, very limited studies have been reported on the process of flower petal pigmentation. In this study, we found significant differences in the anthocyanin contents of petals from different colored azaleas, and the results of quantitative real-time PCR indicated that the R2R3 MYB genes, RsMYB12, RsMYB90, and RsMYB123, showed significant expression changes during the petal coloration in azalea petals; therefore, we hypothesized that RsMYB12, RsMYB90, and RsMYB123 might involve in the coloring process of azalea petals by regulating anthocyanin synthesis. This work provides insights into the underlying mechanisms of petal pigmentation in R. simsii and provides candidate genes for flower color breeding of azaleas and other ornamental flowers.