Members of the Metal Tolerance Protein (MTP) family are critical in mediating the transport and tolerance of divalent metal cations. Despite their significance, the understanding of MTP genes in mustard (Brassica juncea) remains limited, especially regarding their response to heavy metal (HM) stress. In our study, we identified MTP gene sets in Brassica rapa (17 genes), Brassica nigra (18 genes), and B. juncea (33 genes) using the HMMER (Cation_efflux; PF01545) and BLAST analysis. For the 33 BjMTPs, a comprehensive bioinformatics analysis covering the physicochemical properties, phylogenetic relationships, conserved motifs, protein structures, collinearity, spatiotemporal RNA-seq expression, GO enrichment, and expression profiling under six HM stresses (Mn²⁺, Fe²⁺, Zn²⁺, Cd²⁺, Sb³⁺, and Pb²⁺) were carried out. According to the findings of physicochemical characteristics, phylogenetic tree, and collinearity, the allopolyploid B. juncea’s MTP genes were inherited from its progenitors, B. rapa and B. nigra, with minimal gene loss during polyploidization. Members of the BjMTP family exhibited conserved motifs, promoter elements, and expression patterns across subgroups, consistent with the seven evolutionary branches (G1, G4–G9, and G12) of the MTPs. Further, spatiotemporal expression profiling under HM stresses successfully identified specific genes and crucial cis-regulatory elements associated with the response of BjMTPs to HM stresses. These findings may contribute to the genetic improvement of B. juncea for enhanced HM tolerance, facilitating the remediation of HM-contaminated areas.

Antimony (Sb), a toxic metalloid, inhibits plant growth and threatens human health. Yellow Stripe-Like (YSL) proteins play crucial roles in metal ion transport and cellular homeostasis. While the OPT gene family has been characterized in some species, its genome-wide organization and functional involvement in Sb stress response remain unexplored in Brassica juncea. Here, we identified 47 high-confidence BjOPT genes and combined transcriptomic approaches to elucidate their regulatory roles under Sb stress. Phylogenetic tree, conserved motifs, and gene structure analyses consistently distinguished the BjOPT and BjYSL subfamilies. Comparative and collinearity analyses indicated that OPT genes in Brassica species (including B. rapa, B. nigra, and B. juncea) expanded independently of whole-genome triplication events. Transcriptomic profiling revealed significant enrichment of differentially expressed genes (DEGs) related to key biological processes (oxidative and toxic stress response, metal ion transport, and auxin efflux) and pathways (glutathione metabolism, MAPK signaling, and phytohormone transduction), highlighting their roles in Sb detoxification and tolerance. Notably, three BjYSL3 (BjA10.YSL3, BjB02.YSL3, and BjB05.YSL3) genes exhibited strong up-regulation under Sb stress. Heterologous expression in yeast demonstrated that both BjA10.YSL3 and BjB02.YSL3 enhance Sb tolerance, suggesting their potential role in transporting Sb–nicotianamine (NA) or phytosiderophore (PS) complexes. These findings advance our understanding of Sb tolerance mechanisms and provide a basis for developing metal-resistant crops and phytoremediation strategies.

Antimony (Sb), a toxic metalloid with significant phytotoxicity and potential carcinogenicity, threatens agricultural safety due to its widespread use. Soybean ( Glycine max L.), a globally important source of edible oil and protein, has been studied for heavy metal resistance, yet its specific responses to Sb stress remain unclear. Using integrated phenotypic, physiological, transcriptomic, and metabolomic analyses of Sb(III)-stressed soybean, we observed dose-dependent phytotoxicity, including leaf wilting, root damage, and biomass reduction. Despite these symptoms, soybean exhibited strong Sb tolerance, accumulation, and translocation capacity. Multi-omics analysis revealed dose-dependent coordinated upregulation of detoxification genes (e.g., ABC transporters , CYPs , and HSP26-A ) and identified three key metabolic pathways contributing to Sb tolerance: (1) flavonoid biosynthesis, (2) alanine, aspartate, glutamate metabolism, and (3) isoquinoline alkaloid biosynthesis. Together, these components may constitute a coherent molecular defense network against Sb toxicity. Our findings provide novel insights into the mechanisms of Sb tolerance in soybean and support the development of resistant cultivars for cultivation in contaminated areas.

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. Using integrated phenotypic, physiological, transcriptomic, and metabolomic analyses of soybean under Sb(III) stress, we observed dose-dependent phytotoxic effects, including leaf wilting, root damage, and reduced biomass. Despite these symptoms, soybean demonstrated strong tolerance to Sb, along with a pronounced capacity for Sb accumulation and translocation. Multi-omics analysis revealed three key pathways contributing to Sb tolerance: (1) flavonoid biosynthesis, (2) alanine, aspartate, glutamate metabolism, and (3) isoquinoline alkaloid biosynthesis and identified a dose-dependent, coordinated upregulation of stress-responsive genes (e.g., ABC transporters, CYPs, and PERs). WGCNA combined with yeast heterologous expression identified GmCHI4, GmPER52, and GmPAL1 as potential contributors to enhanced Sb tolerance in soybean. Collectively, these components are proposed to constitute a coordinated molecular defense network underlying Sb tolerance in soybean. Our findings provide a crucial theoretical foundation for the remediation of Sb-contaminated soil and the genetic improvement of Sb-tolerant soybean cultivars.

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.