Integrated multi-omics analysis reveals the molecular defense network underlying antimony tolerance in soybean.

Antimony (Sb), a toxic metalloid with significant phytotoxicity and potential carcinogenicity, poses a threat to agricultural safety due to its extensive use. Soybean (Glycine max L.), a globally important source of edible oil and protein, has been investigated for heavy metal resistance; yet its specific responses to Sb stress remain poorly understood. In this study, integrated phenotypic, physiological, transcriptomic, and metabolomic analyses were applied to elucidate the molecular defense network underlying soybean response to Sb(III) stress. Soybean exhibited dose-dependent phytotoxic effects, including leaf wilting, root damage, and reduced biomass, while tolerating Sb stress up to 90 mg/kg, alongside a pronounced capacity for Sb accumulation and translocation. Multi-omics analysis revealed a coordinated molecular defense network comprising three key pathways, flavonoid biosynthesis, alanine, aspartate, glutamate metabolism, and isoquinoline alkaloid biosynthesis, that collectively contribute to Sb tolerance. Key components of this network, including genes (e.g., ABC transporters, PALs, CHIs, and PERs) and metabolites (e.g., isoliquiritigenin, chlorogenic acid, L-aspartate, L-glutamate), were identified as critical mediators. Functional validation via yeast heterologous expression demonstrated that GmCHI4, GmPER52, and GmPAL1 enhanced Sb tolerance, further supporting their roles within this defense network. These findings delineate a multi-layered molecular defense network and provide precise genetic and metabolic targets for breeding Sb-tolerant soybean cultivars.