Metagenomic profiling of Poa alpigena rhizosphere and bulk soil microbiomes across differing land-use contexts in the Qinghai lake alpine wetland.

The Qinghai Lake alpine wetland, a critical ecological barrier on the northeastern Qinghai-Tibet Plateau, relies heavily on its rhizosphere microbial communities to sustain regional ecosystem stability. This study investigated the dominant forage grass Poa alpigena across sites subjected to varying anthropogenic disturbance intensities-high-intensity grazing (Haergai, HE), moderate grazing (Sanjiaocheng, SJ), and an undisturbed control (Haixinshan, X)-using metagenomic sequencing to compare rhizosphere and non-rhizosphere soil microbiomes. Results identified Proteobacteria, Actinobacteria, and Planctomycetes as the dominant phyla, collectively representing > 55% of microbial composition. At the genus level, Streptomyces, Pseudomonas, and Sphingomonas exhibited significant enrichment. α-Diversity (Chao1 and Shannon indices) was markedly higher in rhizosphere than non-rhizosphere soils, while β-diversity (PCoA) revealed distinct spatial clustering. Mantel tests identified soil moisture, pH, and conductivity as key drivers of microbial community assembly. Functional profiling showed non-rhizosphere microbes were enriched in environmental stress-response pathways (e.g., quorum sensing, lipopolysaccharide biosynthesis), whereas rhizosphere microbes dominated metabolic processes like valine/leucine degradation and arginine biosynthesis. LEfSe analysis further highlighted site-specific taxa: Streptomyces and Sphingopyxis in Haergai, Nocardioides in Sanjiaocheng, and Pseudomonas with Azospirillum in Haixinshan. These findings deepen our understanding of microbial responses to anthropogenic pressures and offer actionable insights for restoring degraded alpine grasslands.