Carotene hydroxylase DcCYP97A3 affects carotenoid metabolic flow and taproot color by influencing the conversion of α-carotene to lutein in carrot.

The color diversity of non-purple carrot taproots is mainly affected by carotenoid species and content. Carrot cytochrome P450 carotene β-ring hydroxylase (DcCYP97A3) may influence carotenoid accumulation in carrots; however, the roles of in carrot remain unclear. Compared to the orange carrot 'Kurodagosun, KRD', the yellow carrot 'Yellowstone, YST' had greater relative transcript levels of . DcCYP97A3 was shown to catalyze the β-ring hydroxylation of α-carotene to create zeaxanthin when it was expressed in accumulating α- and β-carotene. Expression of the of 'YST' in DcCYP97A3 functionally deficient orange carrot 'KRD' resulted in yellow taproots, decreased α-carotene and β-carotene content, decreased α-/β-carotene ratio, and increased lutein content. In carrots overexpressing the gene, the transcript levels of and were significantly upregulated and downregulated, respectively. Gene editing of in 'YST' resulted in knockout mutants with significantly reduced levels of lutein and β-carotene and significantly upregulated transcript levels of and . These findings advance our knowledge of the molecular mechanisms behind carrot carotenoid metabolism.