SlLCYB2 affects the accumulation of carotenoids in tomato fruits

Lycopene (3-cyclases, essential enzymes at the branch point of the carotenoid biosynthesis pathway, critically regulate the composition and balance of carotenoids in plants. This study investigates the role of the SlLCYB2 gene, a novel chloroplast-specific lycopene (3-cyclase, in the carotenoid biosynthesis of tomato fruits. The molecular cloning and functional characterization of SlLCYB2 were conducted to evaluate its effects on carotenoid accumulation. Overexpression of SlLCYB2 resulted in a significant redirection of the carotenoid metabolic flux towards (3-carotene at the expense of lycopene, leading to a marked decrease in total carotenoid content and a characteristic orange hue in transgenic tomato fruits. This metabolic shift was accompanied by alterations in the expression of genes related to cell wall modification and Abscisic acid (ABA) signaling, which delayed fruit softening and improved postharvest shelf life. Our results highlight the potential of SlLCYB2 as a genetic target for enhancing the nutritional value and postharvest quality of tomatoes. This study provides insights into the molecular mechanisms governing carotenoid biosynthesis, fruit ripening, and the interplay between these processes and ABA signaling, offering a foundation for targeted genetic manipulations to develop tomatoes with improved nutritional content and storage characteristics.