Differences in bacterial community composition and diversity in the rhizosphere and surrounding environment of wild soybean (Glycine soja) under different salt stress conditions

The Yellow River Delta region is densely covered with saline-alkali land. Wild soybean (Glycine soja Siebold & Zucc.), as a typical plant in this area, exhibits notable salt tolerance. Consequently, understanding the composition and function of its rhizosphere microbiota is therefore crucial for deciphering the mechanisms underlying its environmental adaptation. This study focused on wild soybeans from the Yellow River Delta region as the research subject. Salt stress treatments of varying concentrations were established, and Illumina-based high-throughput 16 S rRNA gene sequencing was employed to investigate the effects of salt stress on the composition and diversity of bacterial communities in both the rhizosphere and surrounding aquatic environments of wild soybeans. The findings revealed that salt stress significantly decreased the diversity of bacterial communities in both the rhizosphere and aquatic environments and altered their bacterial community structures. At the phylum level, Proteobacteria predominated across all samples, with a notable upward trend in relative abundance as salinity increased. In the rhizosphere of wild soybeans, Cyanobacteria accumulated progressively with increasing salinity. At the genus level, the relative abundances of Pseudomonas and Acinetobacter significantly increased (p < 0.05) in response to elevated salinity levels. The roots of wild soybeans harbor Pseudomonas, Shewanella, and Rhizobium, which contribute to enhancing salt stress resistance. Research has found that under salt stress conditions, the dominant bacterial communities in the rhizosphere and surrounding environments of wild soybeans may shift toward more salt-tolerant species. These bacteria likely play a critical role in facilitating the adaptation of wild soybeans to saline environments. This study not only deepens our understanding of microbial-mediated salt tolerance mechanisms but also provides valuable technical insights for utilizing saline-alkali lands and breeding stress-tolerant crops.