Identification of QTLs linked to bioactive flavonoids and glycosides in the apricot fruit (Prunus armeniaca L.)

Apricots are highly valued for their nutritional and functional properties, largely due to their rich content of bioactive compounds, particularly flavonoids, phenolic acids, and glycosides. These secondary metabolites are associated with antioxidant, anti-inflammatory, and antimicrobial activities, as well as contributing to fruit flavor, aroma, and overall quality. This study investigated the genetic basis of flavonoid and glycoside accumulation by integrating untargeted metabolomics (UPLC-QToF-MS/MS) with QTL mapping in two segregating apricot populations: 'Bergeron' × 'Currot' and 'Goldrich' × 'Currot'. Five flavonoids (catechin, epicatechin, myricitrin, quercetin, and rutin), three phenolic acids (coumaric, caffeic, and ferulic acids), and five glycosides (kiwiionoside, neryl arabinofuranosyl-glucoside, vanilloyl glucose, zizybeoside I, and 3-hydroxy-beta-ionol 3-[glucosyl-(1- > 6)-glucoside]) were tentatively identified from metabolite features showing significant differences between parental genotypes (ANOVA, P < 0.05) and subsequently detected across parents and seedlings. QTL mapping identified loci associated with epicatechin on linkage group 1 (LG1), myricitrin and rutin on LG7, and vanilloyl glucose on LG4. In contrast, zizybeoside I exhibited polygenic genomic architecture, with associations distributed across several chromosomes, predominantly on LG2, LG3, and LG5. These findings highlight the genetic loci associated with flavonoid and glycoside biosynthesis, providing valuable insights into marker-assisted selection (MAS) strategies in apricot breeding programs aimed at enhancing the nutritional and functional value of this species.