Abstract: To understand the effects of different grazing durations in artificial reseeding grasslands on the symbiotic relationship between soil arbuscular mycorrhizal fungi (AMF) and plants and the composition of AMF community, we investigated plant community diversity, mycorrhizal colonization rate, AMF spore density and mycelium density in soil of abandoned land, grassland grazed for 25 years, and grassland grazed for 5 years in Yunnan Provincial Breeding and Promotion Center, and analyzed the community composition of AMF in soil by Illumina sequencing. The results showed that compared with abandoned land, grazing increased the proportion of legumes in grasslands and decreased AMF mycelium density, but there was no significant difference in soil AMF spore density and mycorrhizal colonization rate between grazed grasslands and abandoned land. Grazing increased AMF community richness compared to abandoned land, but the richness did not change significantly with increasing grazing duration. The AMF community str〖JP2〗ucture varied significantly across different grazing durations. Endemic species of AMF -Glomus-group-B-Glomus-ORVIN-GLO4-VTX00278- emerged in the grassland grazed for 25 years. Legume importance value, soil pH, NH₄⁺-N and available phosphorus content were the main factors affecting the composition of AMF community.

Key words: grazing, symbiotic relationship, Illumina sequencing, arbuscular mycorrhizal fungi, community structure.