Tissue-Resolved Metabolomic Profiling of Ten Prunus salicina × P. armeniaca Cultivars Reveals Peel-Flesh Metabolic Differences Associated with Fruit Color and Antioxidant Capacity.

Prunus salicina × P. armeniaca, an interspecific hybrid of Chinese plum and apricot, shows substantial variation in peel and flesh color and quality traits. Ten cultivars were characterized by integrating physicochemical measurements, spectrophotometric assays of phytochemical content and antioxidant capacity, and widely targeted ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) metabolite profiling. Tissue type was the main source of chemical variation. Peel contained higher total phenolic (TPC), flavonoid (TFC), and anthocyanin (TAC) contents and greater 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging capacity, 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging capacity, and ferric reducing antioxidant power (FRAP), whereas flesh showed higher relative abundances of sugars, sugar alcohols, organic acids, amino acid derivatives, lipids, nucleotides, and terpenoids. Among 248 annotated metabolites, flavonoids were predominant, and color-related differentially accumulated metabolites were mainly enriched in phenylpropanoid and flavonoid pathways, particularly in purple-yellow comparisons. Integrating tissue-specific correlations, random forest models, and color-gradient patterns prioritized cyanidin-3-O-glucoside, dihydromyricetin, genistin, and orientin as cross-tissue color-associated metabolites. Cyanidin-3-O-glucoside showed the strongest association with coloration and anthocyanin content, whereas 4'-O-glucosylvitexin was strongly connected with phenolic, flavonoid, anthocyanin, and antioxidant traits. Comprehensive nutritional quality index rankings further distinguished cultivar-specific peel and flesh quality profiles. These results provide a tissue-resolved metabolic basis for evaluating and utilizing plum-apricot hybrid germplasm.