Microbial Assembly and Stress-Tolerance Mechanisms in Salt-Adapted Plants Along the Shore of a Salt Lake: Implications for Saline–Alkaline Soil Remediation

Investigating the microbial community structure and stress-tolerance mechanisms in the rhizospheres of salt-adapted plants along saline lakes is critical for understanding plant-microbe interactions in extreme environments and developing effective strategies for saline-alkaline soil remediation. This study explored the rhizosphere microbiomes of four salt-adapted species (<i>Suaeda glauca</i>, <i>Artemisia carvifolia</i>, <i>Chloris virgata</i>, and <i>Limonium bicolor</i>) from the Yuncheng Salt Lake region in China using high-throughput sequencing. Cultivable salt-tolerant plant growth-promoting rhizobacteria (PGPR) were isolated and characterized to identify functional genes related to stress resistance. Results revealed that plant identity and soil physicochemical properties jointly shaped the microbial community composition, with total organic carbon being a dominant driver explaining 17.6% of the variation. <i>Cyanobacteria</i> dominated low-salinity environments, while <i>Firmicutes</i> thrived in high-salinity niches. Isolated PGPR strains exhibited tolerance up to 15% salinity and harbored genes associated with heat (<i>htpX</i>), osmotic stress (<i>otsA</i>), oxidative stress (<i>katE</i>), and UV radiation (<i>uvrA</i>). Notably, <i>Peribacillus</i> and <i>Isoptericola</i> strains demonstrated broad functional versatility and robust halotolerance. Our findings highlight that TOC (total organic carbon) plays a pivotal role in microbial assembly under extreme salinity, surpassing host genetic influences. The identified PGPR strains, with their stress-resistance traits and functional gene repertoires, hold significant promise for biotechnological applications in saline-alkaline soil remediation and sustainable agriculture.