Diversity of Soil Fungi, Entomopathogenic Fungi and Their Driving Factors in the Eastern Tanggula Mountains in the Qinghai–Tibet Plateau

This study aims to elucidate the soil fungal community structure, the distribution of entomopathogenic fungi (EPF) resources, and their driving mechanisms in the alpine grassland of the northern side of the eastern Tanggula Mountains in the Qinghai–Tibet Plateau. Five representative sites were established along an elevational gradient of 4000–5100 m, and 15 soil samples were collected. High-throughput sequencing (ITS region) and an insect baiting method were combined to analyze fungal community composition and diversity. LEfSe analysis, random forest modeling, redundancy analysis (RDA), and network analysis were employed to reveal the environmental driving mechanisms of community assembly. A total of 412 fungal species belonging to 303 genera were annotated, with Ascomycota as the dominant phylum. At the high-elevation site Jie-duo Town, Zaduo County (ZD-JD), the cold-tolerant ectomycorrhizal fungus Inocybe was absolutely dominant (17.18%). The low-elevation site Dong-ba Town, Nangqian County (NQ-DB), was enriched with the saprotrophic genus Mortierella (10.34%) and EPF taxa. The mid-elevation site Zhuo-xiao Town, Nangqian County (NQ-ZX), was characterized by Solicocozyma (11.88%) and exhibited the highest network complexity. Alpha diversity decreased with increasing elevation. A total of 35 EPF strains were isolated via the baiting method, predominantly Metarhizium anisopliae, M. brunneum, and M. robertsii, with the highest number of isolates (16 strains) recovered from NQ-DB. Elevation indirectly drove community assembly by regulating temperature and plant productivity. The soil fungal community structure in the alpine grassland of the eastern Tanggula Mountains exhibits significant spatial heterogeneity along the elevational gradient. Low-elevation habitats serve as hotspots for EPF resources, while high-elevation isolates harbor potential stress-resistance genes. The combination of culture-dependent and sequencing-based approaches provides a reliable strategy for microbial resource surveys in extreme environments.