Abstract
INTRODUCTION: Pyrus betulifolia is tolerant to diverse environmental conditions and is commonly planted in infertile habitats (such as beaches and ridges) to conserve arable land for cereal crops. Symbiotic fungi in the rhizosphere and root endosphere benefit host plants by enhancing their resilience to nutritional deficiencies under stressful conditions. However, the mechanisms underlying the assembly of these symbiotic fungal communities in the roots of P. betulifolia across different habitats remain poorly understood. METHODS: Pyrus betulifolia of 30-year-old were selected from five sites in northern China to investigate the assembly of fungal communities in the rhizosphere and root endosphere. Soil samples were collected to assess the heterogeneity of the environment surrounding each plant. Procrustes analysis, variance partitioning analysis, and ordination regression analysis were employed to explore the ecological relationships between soil factors and fungal community composition. RESULTS: The rhizosphere fungal community exhibited higher richness, greater diversity and lower structural variability compared to the root endosphere. Additionally, the rhizosphere supported a fungal network with higher abundance and stronger connectivity than the root endosphere. The composition of fungal communities varies significantly among different regions. In both the rhizosphere and root endosphere fungal communities, the number of genera specific to mountainous regions was larger than those in plain areas and saline-alkali areas. Null model-based analyses indicated that the assembly of rhizosphere and root endosphere fungal communities in P. betulifolia was mainly governed by stochastic processes. Specifically, in non-saline-alkali soils, the assembly of rhizosphere fungi was primarily driven by dispersal limitation, whereas the assembly of root endosphere fungi was dominated by ecological drift. In saline-alkali soils, both rhizosphere and root endosphere fungal communities were primarily influenced by ecological drift. CONCLUSION: The assembly of root-associated fungal communities in P. betulifolia is not only driven by soil physicochemical properties but also influenced by root compartment niche and topography. Moreover, the impact intensity of the root compartment niche is greater than topography. Specifically, the assembly of the rhizosphere fungal community was primarily influenced by alkaline nitrogen (AN) and alkaline phosphatase (ALP), while the root endosphere fungal community was more strongly affected by pH and sucrase (SUC). These findings could provide valuable insights for the design of beneficial root-associated microbiomes to enhance fruit tree performance.