Role of Starch Accumulation at the Mature Green Stage in Shaping Tomato Fruit Quality

Tomato (Solanum lycopersicum) is a globally important vegetable crop, with fruit quality being a major focus of research. Starch serves as the primary carbohydrate reserve during early fruit development and functions as a key carbon precursor for flavor compound biosynthesis in later stages. To elucidate the role of starch accumulation in determining ripe fruit quality, we analyzed the relationship between starch content in mature green fruits and flavor-related traits across eight tomato cultivars. The results demonstrated that starch content at the mature green stage showed a significantly positive correlation with total soluble solids (TSS) content (r = 0.922) and a significantly positive correlation with total acidity content (r = 0.783) in red-ripe fruits. Furthermore, the expression levels of starch synthesis gene AGPS1 and degradation gene PWD at the mature green stage were both significantly positively correlated with the final fruit TSS levels. These findings highlight the important role of starch accumulation during the mature green stage in shaping final fruit quality, providing a theoretical basis for breeding high-quality tomato varieties.