Screening of salt-tolerant soybean germplasm and study of salt-tolerance mechanism.

key messageScreening of salt-tolerant soybean varieties, identification of key genes and verification of gene function through salt-tolerance assessment, transcriptome profiling and soybean hairy root transformation experiments. Screening and breeding of salt-tolerant soybean varieties is essential to increase the area and yield of soybean on saline-alkaline soils. In this study, 81 soybean varieties were systematically assessed for salt tolerance during both germination and early seedling development stages. Based on their salt-tolerance capacity, the varieties were categorized into four distinct groups. Physiological analysis revealed that the highly salt-tolerant genotype effectively restricted ions accumulation in roots through compartmentalization mechanisms, while subsequent biochemical assays demonstrated its superior antioxidant enzyme activity (particularly SOD and CAT), thereby mitigating membrane system damage under NaCl stress. Comparative transcriptome profiling between salt-tolerant and sensitive cultivars identified 3588 differentially expressed genes (DEGs) predominantly involved in ion transport, oxidative stress, and photosynthesis. Functional validation through preliminary experiments using the soybean hairy root transformation method highlighted the potential regulatory roles of the candidate gene (Gm10G262850v4) in salt stress responses. These findings provide insights into the mechanisms of soybean salt tolerance and facilitate the breeding of salt-tolerant soybean varieties.