Comparative Transcriptome Analysis Revealed Key Regulatory Genes Under PEG-Induced Osmotic Stress in Soybean

Soybean is a critical oil and protein crop for both food and forage production; however, its growth and development are severely impacted by drought stress. Nevertheless, the molecular regulatory mechanisms underlying drought tolerance in soybean remain poorly understood. In this study, two soybean varieties, Jindou 21 (JD21, drought-tolerant) and Suinong 26 (SN26, drought-sensitive), were used as experimental materials and subjected to 15% PEG6000 to simulate drought stress. Roots and leaves were sampled at 0 h, 6 h, and 12 h after treatment to determine physiological indicators and conduct RNA-seq analysis. The results showed that JD21 exhibited a lower malondialdehyde (MDA) content but higher soluble sugar and proline contents than SN26. A total of 2603 and 3128 osmotic-stress-responsive genes were identified in the roots and leaves of SN26 and JD21, respectively. Additionally, 256 genes in the roots and 215 genes in the leaves showed consistent differential expression between the two varieties across the three treatment time points. KEGG enrichment analysis revealed that the differentially expressed genes were significantly enriched in pathways related to glutathione metabolism, arginine and proline metabolism, glycolysis/gluconeogenesis, and starch and sucrose metabolism. Within these pathways, the functions of GmGST, GmAMD1, GmADH1, GmENO, GmsacA, and GmSUS3 were validated through transgenic hairy root assays, demonstrating that these genes play positive regulatory roles in osmotic stress response. This study provides valuable data for elucidating plant PEG-induced osmotic-stress-response mechanisms and offers theoretical support for drought-resistant soybean breeding.