Unveiling CcR2R3-MYB: A Key Regulator of Leaf Pigmentation in Cymbidium Orchids

Leaf coloration, a critical trait in ornamental foliage plant breeding, is influenced by chlorophyll, carotenoids, and flavonoids, which dictate plant aesthetic and economic value. The regulatory role of MYB transcription factors in leaf pigmentation is well recognized. However, their specific influence on Cymbidium leaf coloration remains obscure despite the genus’s global economic importance. This study utilized a novel orchid mutant with leaf variegation as the experimental material to investigate the role of CcR2R3-MYB genes. This research has successfully identified and cloned a novel MYB transcription factor, namely CcR2R3-MYB, from a leaf variegation mutant of Cymbidium. The expression level of CcR2R3-MYB was significantly higher in the mutant plants, with the protein predominantly localized in the nucleus. Phylogenetic analysis indicates that the gene is closely related to AtMYB106 and DhMYB1 and regulates leaf cell morphogenesis and color variation in Cymbidium. Overexpression of CcR2R3-MYB resulted in a yellowish-green and a reduction in photosynthetic pigment content in the Dendrobium. These findings not only lay a foundation for unraveling the mechanism by which CcR2R3-MYB regulates the development of orchid foliage art but also hold significant implications for creating new orchid germplasm and the enhancement of varietal traits.