Understanding the ecological drivers of plant-associated microbiota is essential for predicting grassland ecosystem resilience. This study aimed to characterize the community structure, functional potential, and soil environmental drivers of rhizosphere and root endophytic microbiota associated with Polygonum divaricatum across three Hulunbuir Grassland sites. A nested sampling design was applied with three replicated plots per site, from which paired rhizosphere soil and root samples were collected. Each sample represented a composite of 15 plants, yielding six samples per site (total n = 18) and allowing the separation of compartmental and environmental effects on community assembly. P. divaricatum plays a key role in nutrient cycling and soil stability; however, its rhizosphere and root microbiomes remain poorly characterized. Fungal diversity was consistently higher in the root endosphere, whereas bacterial diversity was greater in rhizosphere soils. Fungal assemblages were dominated by Ascomycota and Mortierellomycota, primarily represented by Mortierella and Trichoderma, while bacterial communities were dominated by Actinomycetota and Pseudomonadota, enriched in Bradyrhizobium and Pseudonocardia. Community differentiation reflected strong compartmental filtering and responses to soil pH, organic carbon, nitrogen, and enzyme activities. Functional prediction indicated clear compartmental partitioning: in the rhizosphere, bacterial communities were enriched in pathways related to carbon and nitrogen metabolism and secondary metabolite biosynthesis, whereas in the root endosphere, functional profiles were more associated with transport, uptake, and fermentation; fungal communities were dominated by saprotrophic and symbiotrophic guilds. These findings demonstrate that soil biochemical gradients and host-driven filtering jointly structure the P. divaricatum microbiome, providing ecological insights into plant–microbe–soil interactions and the maintenance of grassland ecosystem stability.
Ren et al. (Fri,) studied this question.