Metabolomic insights into hydrogen gas-mediated regulation of growth and isoflavone biosynthesis in germinated soybean

This study employed metabolomics to elucidate the mechanisms underlying hydrogen gas (H₂) treatment on seed germination, growth status, and isoflavone metabolism in soybeans (Glycine max, variety: Dongnong 690). Treatment with 0.5 ppm H₂ significantly enhanced the length (17.5 %) and fresh weight (10.2 %) of germinated soybeans while markedly increasing the content of isoflavone. H₂ treatment unregulated the activity and gene expression of key enzymes in the phenylpropanoid pathway, including phenylalanine ammonia lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-coumarate coenzyme A ligase (4CL), Chalcone Synthase (CHS), Chalcone isomerase (CHI), Isoflavone synthase (IFS), and Flavone synthase I (FNSI). Metabolomic profiling revealed that H₂ modulates the growth of germinated soybeans by influencing metabolic pathways related to energy, carbohydrates, and amino acids. Furthermore, the biosynthesis pathways of mangiferin alkaloids and phenylpropanoid alkaloids were closely associated with the observed increase in isoflavone content. H₂ treatment also significantly increased β-glucosidase activity in germinated soybeans. These findings demonstrate that H₂ treatment serves as an effective bioregulatory strategy that not only promotes the biomass accumulation in germinated soybean but also enhances its nutritional value by facilitating the conversion of isoflavone glucosides to more bioactive glycoside forms.