**The Molecular Mechanisms Underlying the Formation of Quality Traits in Horticultural Crops**

The formation of quality traits in horticultural crops is a complex process involving the regulation of multiple molecular mechanisms. These mechanisms directly or indirectly influence the crop's appearance, taste, aroma, and nutritional value, among other quality features. The accumulation of sugars in fruits is crucial for quality formation, and sugar accumulation is associated with several molecular mechanisms. Shui et al. [8] investigated lychee fruit quality by applying excessive calcium fertilizer and found that downregulation and expression of the CHS gene family may lead to the reduced accumulation of chalcones, resulting in oxidative damage to fruit flesh and the inhibition of soluble sugar accumulation in the tissue. Xu et al. utilized transcriptomic approaches to study the gene expression profile underlying grape skin color formation and identified key MYB genes involved in skin color transitions [9]. Sun et al. [10] performed cluster analyses on chrysanthemum varieties, dividing them into five categories and summarizing the typical plant configurations of each variety. Finally, they conducted genome-wide association studies (GWASs) to identify potential functional genes. A comprehensive understanding of these mechanisms contributes to optimizing the quality and yield of horticultural crops.
