Space and soil drive differences in the rhizosphere microbial composition and co-occurrence network of Thymus mongolicus in Northern China

Previous research on T. mongolicus has mainly focused on community characteristics or allelopathic effects, with limited attention given to microbial communities, especially the geographical distribution patterns and co-occurrence network differences of rhizosphere microorganisms at large scales. Therefore, this study collects rhizosphere soil from T. mongolicus in 20 regions of northern China. Five T. mongolicus are randomly sampled in each region, and their rhizosphere soils are mixed and divided into five replicates. The differences in rhizosphere microbial community composition and co-occurrence networks across different regions are examined using 16S and ITS analysis, and the mechanisms underlying these differences are explored. The results confirmed that the diversity of rhizosphere fungi in the east region is significantly higher than in the west ( p < 0.05). In contrast, the diversity of rhizosphere bacteria does not exhibit a significant difference between the two regions ( p > 0.05). Rhizosphere fungi are more influenced by stable spatial factors, such as longitude, latitude, and altitude ( p < 0.05), while rhizosphere bacteria are more impacted by soil factors, such as TP and pH (p < 0.05). Both rhizosphere fungi and bacteria conform to the distance attenuation model, but rhizosphere fungi are more strongly affected by geographical distance than rhizosphere bacteria. Compared to the west region, the microbial co-occurrence network in the east region exhibits more modules and higher topological parameters. This study confirms that rhizosphere microorganisms also follow the distance decay model, providing valuable insights into the geographical distribution of rhizosphere microorganisms at a large scale. • Different mechanisms influence the composition of rhizosphere fungi and rhizosphere bacteria. • Rhizosphere fungal similarity is more distance-dependent than bacteria similarity. • East region's microbial network is more complex than that of the west.