Combined metabolome and transcriptome analyses of quality components and related molecular regulatory mechanisms during the ripening of Huangjin Peach

Huangjin Peach is highly nutritious with cinsiderable market potential. Flavonoids, sugars, and acids are among the key compounds affecting the quality of yellow peaches. In this study, we analyzed the metabolites and gene expression of Huangjin Peach to explain the quality formation mechanism during the ripening period (including the young fruit, color change, and mature stages). We explored the biosynthetic pathways of flavonoids, sugars, and organic acids through metabolomics (LC-MS/MS) and transcriptomics (RNA-seq) approaches. A total of 864 metabolites were identified during the ripening of Huangjin Peach. Flavonoids increased significantly mainly at the color change stage and accumulated at the mature stage. During the combined transcriptomic and metabolomic analyses, CHS, F3′H, DFR, and A3GT were identified as the main enzyme genes regulating flavonoid synthesis, as well as the key factors affecting fruit color. Sugar alcohols accumulated significantly in Huangjin Peach during the ripening period, and organic and phenolic acids decreased significantly during the color change stage, which affect the quality and taste of fruits. Most metabolites and genes changed dramatically during the color change stage, indicating that the color change stage is critical for fruit quality formation. The expression of key genes was verified by qRT-PCR. Our results explained some of the key fruit quality formation mechanisms of Huangjin Peach, which provide a valuable foundation for the improvement and development of functional foods.