Legume Genomics and Genetics 2026, Vol.17, No.1, 32-48 http://cropscipublisher.com/index.php/lgg 39 Functional validation studies have confirmed that individual TFs can markedly enhance drought tolerance. Overexpression of NAC TFs such as GmNAC19 and GmNAC3 improves root growth, chlorophyll retention, osmolyte accumulation and antioxidant enzyme activities, while reducing ROS and MDA, thereby conferring stronger drought resistance in soybean and yeast models (Amin et al., 2025). ERF family members like GmERF205 and AP2/ERF144 enhance survival, root development and yield under drought, and activate downstream stress-responsive genes in transgenic soybean (Wang et al., 2022; Wu et al., 2025). bZIP TFs, including GmbZIP2 and GmTRAB1, increase tolerance by boosting proline and antioxidant systems, enhancing ABA sensitivity and stomatal regulation, and upregulating LEA, GST and other stress-related genes (Yang et al., 2020; Li et al., 2024). Additional families such as HD-ZIP (GmHdz4), NF-YB (GmNFYB17) and TGA-bZIPs also positively regulate drought tolerance, often through improved root architecture, ABA-related signaling, and fine-tuned redox homeostasis (Zhong et al., 2022). Collectively, these findings establish a multi-family TF hierarchy that integrates ABA, ROS, and developmental cues into coherent transcriptional programs under drought. 4.3 Metabolic pathways and drought resistance regulatory networks Pathway enrichment and network analyses of soybean drought DEGs consistently reveal extensive remodeling of primary and secondary metabolism. Key pathways include photosynthesis, carbon fixation, glycolysis/gluconeogenesis, the TCA cycle, pentose phosphate pathway, amino acid and sugar metabolism, and hormone biosynthesis and signaling (Wang et al., 2022). Under drought, many photosynthesis-related genes are downregulated, reflecting reduced carbon assimilation, whereas genes involved in carbohydrate metabolism and TCA cycle are reprogrammed to support energy balance and osmotic adjustment (Shahriari et al., 2022). Secondary metabolite pathways-particularly phenylpropanoid, flavonoid, and isoflavonoid biosynthesis-are strongly enriched and associated with accumulation of flavonoids and related compounds that contribute to ROS scavenging and membrane protection. Integrative transcriptome-metabolome studies at the seedling and grain-filling stages show concordant upregulation of flavonoid/isoflavone pathway genes and metabolites in tolerant genotypes or melatonin-treated plants, highlighting these pathways as central biochemical buffers against drought damage. Regulatory network reconstruction, using WGCNA, protein-protein interaction (PPI) and promoter motif analysis, has begun to map how TFs and signaling components control these metabolic shifts. Co-expression modules associated with drought contain hub genes linked to photosynthesis, cytokinin dehydrogenase activity, systemic acquired resistance, secondary metabolite biosynthesis, and antioxidant systems, with TFs from NAC, WRKY, bZIP, AP2/ERF, NF-Y and TGA families occupying central positions (Shahriari et al., 2022; Sun et al., 2022). In tolerant cultivars, hormone-related pathways, notably ABA, jasmonic acid and brassinosteroid signaling, as well as Ca2+ and MAPK cascades, are more strongly represented among DEGs, suggesting tighter coupling of environmental perception, transcriptional control and downstream metabolism . Newly proposed data-driven feature engineering pipelines that integrate multi-omics and non-omics datasets further refine candidate drought-tolerance genes and pathways beyond classical WGCNA, offering a scalable framework to prioritize regulatory nodes for breeding and engineering (Kao et al., 2025). Together, these studies depict drought resistance in soybean as an emergent property of interconnected transcriptional, hormonal and metabolic networks that reallocate resources, enhance cellular protection, and stabilize growth under water-limited conditions. 5 Expression Regulation and Functional Validation of Drought Resistance-Related Genes in Soybean 5.1 Construction of transcriptional regulatory networks Transcriptome-scale analyses in soybean under drought stress have enabled the reconstruction of transcriptional regulatory networks that connect sensing, signaling, and downstream defenses. Co-expression and systems biology approaches, such as weighted gene co-expression network analysis (WGCNA), cluster thousands of differentially expressed genes into modules associated with physiological traits or drought treatments, revealing hub genes and central transcription factors (TFs) that coordinate pathway-level responses (Shahriari et al., 2022).
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