Metagenomic Insights into Regional Differences in the Rhizosphere Microbial Communities of Stellera chamaejasme L. in Inner Mongolia

Rhizosphere microorganisms are important components of grassland ecosystems, but the rhizosphere microbiome of the poisonous and medicinal plant Stellera chamaejasme L. remains poorly characterized. In this study, shotgun metagenomic sequencing was used to compare the taxonomic composition, community structure, differentially enriched taxa, and KEGG-based functional potential of rhizosphere microbial communities associated with S. chamaejasme from three typical steppe regions in Inner Mongolia. Acidobacteria, Proteobacteria, and Actinobacteria were the dominant phyla, while Sphingomonas, Bradyrhizobium, and Streptomyces were among the dominant genera. Genus-level profiles and ordination analysis showed region-associated community patterns, and rarefaction curves indicated that sequencing depth was sufficient to capture most detectable taxa. LEfSe analysis identified region-associated differentially enriched taxa, including Sphingomonas-, Bradyrhizobium/Nitrospira-, and Streptomyces/Solirubrobacter-associated taxa. KEGG annotation suggested broadly similar major functional categories across regions, with some differences in the relative abundance of metabolic pathways. These results provide baseline metagenomic information on S. chamaejasme rhizosphere communities. Because of the limited replication and lack of soil physicochemical measurements, ecological mechanisms should be tested in future studies.