Carotenoid Pigment Accumulation in Horticultural Plants

Carotenoids are a group of widely distributed natural pigments. They give many horticultural plants the bright red, orange, and yellow colors, as well as the aroma and flavor. Carotenoids enhance the health value and represent an essential quality trait of horticultural products. Significant efforts have been made to correlate specific carotenoid production with pathway gene expression. Some transcription factors that directly regulate transcription of the pathway genes have been identified. Horticultural crops have evolved with complicated and multifaceted regulatory mechanisms to generate the enormous diversity in carotenoid content and composition. However, the diverse and complex control of carotenoid accumulation is still not well understood. In this review, we depict carotenoid accumulation pathways and highlight the recent progress in the regulatory control of carotenoid accumulation in horticultural plants. Because of the critical roles of chromoplasts for carotenoid hyperproduction, we evaluate chromoplast ultrastructures and carotenoid sequestrations. A perspective on carotenoid research in horticultural crops is provided.