Functional profiling of rhizosphere bacterial communities associated with native plants in soda saline-alkali soils of the Songnen Plain, Northeast China

Soda saline-alkali soils, characterized by high concentrations of sodium carbonates and elevated pH, impair soil health and ecosystem function by altering microbial communities and nutrient cycling. This study combined high-throughput quantitative 16S rRNA amplicon sequencing with soil enzyme assays to characterize bacterial communities in rhizosphere soils collected from five soda saline-alkali-tolerant plant species ( Phragmites australis , Leymus chinensis , Suaeda salsa , Typha angustifolia , and Chloris virgata ) at nine locations across the Songnen Plain in Northeast China. Soil chemistry varied widely (pH 7.72–10.97), with the highest Na + content at Songyuan (SY). Measured enzyme activities were spatially differentiated, with L. chinensis rhizospheres in Qiqihar (QH) showing the highest alkaline phosphatase and catalase activities and Baicheng (BC) exhibiting the highest urease activity. Bacterial alpha diversity was significantly higher in Nong'an (N_A) and BC, whereas only 19 ASVs were shared across all sites, suggesting substantial variation in community composition among locations. The communities were dominated by Pseudomonadota, Gemmatimonadota, Actinomycetota, and Bacteroidota, with Halomonas , Pseudazoarcus , and Mongoliicoccus among the prevalent genera. Pseudomonadota abundance was negatively associated with inferred enzyme activities, whereas Gemmatimonadota was positively associated with catalase, pH, and available phosphorus. 16S rRNA gene-based functional predictions suggested a higher relative abundance of putative functions associated with stress responses and CO 2 –bicarbonate interconversion, including predicted pathways related to nitrogen cycling and osmotic regulation, particularly in QH and BC. The results link rhizosphere bacterial community structure with measured soil functions and inferred adaptive potential in soda saline-alkali soils, highlighting L. chinensis -associated rhizosphere microbiomes as promising candidates for further investigation in microbial-assisted remediation of saline-alkali soils.