Variation in arbuscular mycorrhizal fungal communities across mulberry varieties and soil properties in orchard ecosystems

Mulberry (<italic>Morus alba</italic> L.), a prominent cash crop tree in China, depends on arbuscular mycorrhizal fungi (AMF) for soil nutrient acquisition. However, the composition and drivers of AMF communities in mulberry orchards remain poorly understood. Here, we characterized the AMF communities across six mulberry varieties using MiSeq sequencing of orchard soils in Sichuan Province. Our results revealed that all varieties formed symbiotic associations with AMF, with 'Chuanshang' showing the highest colonization rate. We identified 1334 operational taxonomic units (OTUs), predominantly from <italic>Glomus</italic> (61%) and <italic>Paraglomus</italic> (35%). AMF communities varied significantly across sampling sites, influenced by both mulberry varieties and soil properties. While mulberry varieties dominate initial AMF recruitment through genotype-specific selection, soil properties - particularly phosphorus availability (AP), potassium supply (AK), and soil organic carbon (SOC) subsequently shape community composition through resource-mediated environmental filtering. Variance partitioning indicated that 9.6% of community variation was jointly explained by host varieties and soil factors. Notably, AP and AK had direct negative impacts on AMF diversity, whereas SOC had a notable direct positive effect on soil AMF abundance. This study demonstrates that mulberry varieties and soil properties jointly govern AMF community assembly, with host selection and soil resource availability acting as sequential filters. Our findings highlight SOC as a key enhancer of AMF abundance, while high phosphorus and potassium levels may reduce AMF diversity. These insights provide a basis for optimizing AMF-mediated nutrient management in mulberry orchards, suggesting that maintaining organic carbon and balancing fertilizer inputs could enhance symbiotic efficiency and ecosystem sustainability.