Fungi play crucial roles in nutrient acquisition, plant growth promotion, and the enhancement of resistance to both abiotic and biotic stresses. However, studies on the fungal communities associated with peas (PisumsativumL.) remain limited. In this study, we systematically investigated the ecological effects of host niches (soil, root, stem, leaf, and pod) and genotypes on the diversity and composition of fungal communities in peas using a multi-level approach that encompassed pattern recognition (β-diversity decomposition), mechanism validation (neutral community model testing), and dynamic tracking methods (migration pathway source-tracking). The results revealed that the dominant fungal phyla across niches and genotypes were Ascomycota, Basidiomycota, and Mortierellomycota, and the community structures of the soil–plant continuum were primarily determined by the pea niches rather than genotypes. β-diversity decomposition was largely attributed to species replacement rather than richness differences, indicating strong niche specificity and microbial replacement across microhabitats. Neutral model analysis revealed that stochastic processes influenced genotype-associated communities, while deterministic processes played a dominant role in niche-based community assembly. Source-tracking analysis identified niche-to-niche fungal migration, with Erysiphe, Fusarium, Cephaliophora, Ascobolus, Alternaria, and Aspergillusas the key genera. Migration rates from exogenous to endogenous niches were low (1.3–61.5%), whereas those within exogenous (64.4–83.7%) or endogenous (73.9–96.4%) compartments were much higher, suggesting that the pea epidermis acts as a selective barrier that filters and enriches microbial communities prior to internal colonization. This study provides comprehensive insights into the mechanisms of host filtering, enrichment and microbial sourcing, which increases our understanding of the assembly rules of the pea-associated fungal microbiome.

Karst ecosystem  /  restoration  /  community  /  phoD-harboring bacteria  /  P-cycle multifunctionality  /  rare taxa