Plant compartment niche is more important in structuring the fungal community associated with alpine herbs in the subnival belt of the Qiangyong glacier than plant species

The plant compartment niche (i.e., the host plant provides various microhabitats for the microbial community, such as the rhizosphere, root endosphere, leaf endosphere, and phylloplane) and plant species play a significant role in shaping the plant-associated microbial community assembly. However, in the mycobiome associated with alpine herbs in the subnival belt research, little work has been done to assess the contribution of plant compartment niches and plant species to fungal community variation and to reveal the plant compartment niche differentiation of fungal communities. In this study, we quantified the fungal communities associated with the rhizosphere soil, root endospheres, and leaf endospheres of three alpine herbs (Rheum spiciforme, Eriophyton wallichii, and Rhodiola bupleuroides) in the subnival belt of the Qiangyong glacier using high-throughput DNA sequencing. Our results revealed that the variation in diversity and composition of the fungal community was predominantly shaped by plant compartment niche rather than plant species. Rhizosphere soil exhibited the highest level of fungal diversity and niche breadth, while the lowest level was observed in the leaf endosphere. The fungal community composition significantly differed across different plant compartment niches. Fungal co-occurrence networks of the root endosphere and leaf endosphere were more complex and showed higher centrality and connectedness than the rhizosphere soil. Moreover, we also found that the deterministic process governed the fungal community assembly, and the host plant exerts stronger selection pressure on the leaf endophytes in comparison with the root endophytes. The root endophytes are the primary potential contributors to the leaf endophytes, compared with the fungal community associated with rhizosphere soil. Further, the Pleosporaceae, Davidiellaceae, and Chaetomiaceae were significantly enriched and overlapped in two plant compartment niches (root endosphere and leaf endosphere). Collectively, this study reveals that the variation in the diversity and composition of fungal communities associated with three alpine herbs were primarily affected by plant compartment niches rather than plant species. Additionally, this study also reveals that the diversity, composition, co-occurrence pattern, and assembly process of fungal communities associated with three alpine herbs exhibited plant compartment niche differentiation. These results provide a novel insight into the community assembly and ecological interactions of fungal communities associated with plants in harsh environments.