American ginseng fruit: Antioxidant capacity, bioactive components, and biosynthesis mechanism during development

American ginseng (Panax quinquefolius) is considered as a functional food and a medicinal plant, with its fruit containing valuable bioactive ingredients. However, limited knowledge is available regarding its antioxidant capacity, variation in bioactive components, and biosynthetic pathways at various growth stages. The present study examined the in vitro antioxidant capacity of the American ginseng fruit from Wendeng, Shandong at various growth stages, and conducted metabolomic as well as transcriptomic analyses to elucidate the accumulation patterns and biosynthesis of bioactive compounds. The results showed that antioxidant capacity, total flavonoid content (TFC), and total phenolic content (TPC) in fruits at early, middle, and late developmental stages were significantly higher than those in 4-year-old ginseng roots. Notably, fruits at the early developmental stage exhibited the highest antioxidant capacity, which initially declined and subsequently increased as the fruits continued to grow and develop. TFC and TPC were closely correlated with antioxidant capacity in fruits. Widely targeted metabolomics identified 1,094 metabolites with significant changes throughout fruit development, including 223 terpenoids, 164 phenolic acids, and 149 flavonoids. A total of 139 metabolites were closely associated with antioxidant activity in the American ginseng fruits. Furthermore, several genes, such as DFR, LDOX, F3H, CHI, DDS, CYP, UGT, BAHD, as well as MYB, bHLH, and NAC transcription factors (TFs) were identified to be potentially associated with the fruit flavonoids and ginsenosides biosynthesis and their corresponding regulatory networks. The findings provid valuable insights for enhancing the development and utilization of American ginseng fruits as functional foods as well as advancing their quality and breeding practices.