The regulation of nutrient and flavor metabolism in tomato fruit

The accumulation of nutrients and flavors are important factors that determine the consumption of tomato fruit. Carotenoids, polyphenol and vitamin C belong to antioxidant molecules and have been proven to regulate several biochemical processes and prevent many chronic diseases. In recent years, significant progress has been made in our understanding of the biosynthetic pathway and regulatory networks of these compounds in tomatoes. Numerous genes have been determined which promote the accumulation of these nutrients, such as SlNAC1, SlCCD, SlHY5. Meanwhile, since the mechanisms that control nutrient metabolism during fruit ripening are systematic and sophisticated, there are still many unknown factors that affect their content, which need to be further explored. In addition, not only are nutritional properties important, but flavor profiles play a core role in the market for tomato production. However, it is generally accepted by consumers that many tomato varieties have declined nutrient content and little flavor with people's pursuit of fruit yield and size. Hence, improving their levels are the main objectives of many breeding programs. In order to effectively enhance the nutritional and flavor quality of tomato fruits, we reviewed the critical steps in metabolic pathways of these important nutrients and flavor compounds, summarized key regulators for controlling the accumulation of these compounds, and hope to offer valuable candidate genes for the production of high-quality tomato fruits.