Metabolism and regulation of chlorophyll and carotenoids in tomato fruits

Abstract Tomato (Solanum lycopersicum) is a nutrient-rich and flavorful vegetable, ranking among the most consumed globally. In recent years, consumers have increasingly demanded high-quality tomatoes, prompting the extensive research into the key factors and relevant molecular mechanisms regulating the formation of fruit quality. Coloration is a crucial aspect determining the appearance quality of tomato fruits and directly affecting their commercial value. This coloration is intrinsically linked to the composition and abundance of special chemical compounds in fruits, particularly chlorophyll and carotenoids. Chlorophyll is the predominant pigment accumulated in the early stages of fruit development and plays a vital role in photosynthesis. As the fruit ripens, chlorophyll undergoes gradual degradation, while carotenoids are abundantly synthesized, resulting in a striking color transition from green to red. Chlorophyll and carotenoids are essential natural pigments and antioxidants that are indispensable for both coloration and nutritional value of tomato fruits. This review presents a comprehensive overview of the metabolic pathways and regulatory mechanisms of these metabolites, aiming to provide novel insights and strategies for improving tomato quality to meet the growing consumer demand for fruits with appealing coloration and enhanced nutrients.