A marigold (Tagetes erecta) R2R3-MYB transcription factor TeMYB4 modulates carotenoid accumulation and petal coloration by directly regulating carotenogenic genes

Carotenoids are key pigments responsible for coloration, essential for both plant photosynthesis and human health. Carotenoid content in marigold contributes to petal color and the industrial extraction of lutein. Here, we identified an R2R3-MYB transcription factor, TeMYB4, which acts as a modulator in carotenoid biosynthesis in marigold. Overexpression of TeMYB4 in marigold reduced carotenoids accumulation and led to lighter petal color. Specifically, the major carotenoid contents of phytoene, α-carotene, and lutein were significantly decreased in TeMYB4 -overexpressing marigold plants, whereas β-branch carotenoids were significantly elevated, indicating that TeMYB4 regulates carotenoid content in marigold. Y1H and dual-luciferase report assay proved that TeCCD1 is a key enzyme in the carotenoid degradation pathway in marigold inflorescences, and its transcript was promoted by TeMYB4. In addition, the transcripts of TePSY1 and TeNCED1 were suppressed in TeMYB4-overexpressing marigold transgenic lines through direct binding of TeMYB4 to their promoters. Our research will broaden the understanding of the intricate molecular pathways in marigold carotenoid biosynthesis and provide a valuable approach to expedite its breeding. • A R2R3-MYB TF related to carotenoids biosynthesis was identified in marigold. • Constitutive overexpression of TeMYB4, through stable transformation of marigold changed petal color. • TeMYB4 directly regulated expression levels of TeCCD1 , TePSY1 , and TeNCED1 , and decreased the synthesis of carotenoids.