Soil phytopathogenic fungi communities correlate and influence the plant diversity in latitudinal natural forests

Soil phytopathogenic fungi has significant risk to forest health, yet their distribution patterns and keydriving factors within forest ecosystem remain unclear. This study analysis the soil phytopathogenic fungi diversity and key influence factors across 30 natural forest sites spanning approximately 2,500 kilometers along a latitudinal gradient in China utilizes Illumina Miseq sequencing. Results indicated that 3.07% of the soil fungi were identified as plant pathogens, encompassing 119 genera and 1,227 operational taxonomic units (OTUs). Regression analysis reveals that the Shannon index and richness of soil phytopathogenic fungi significantly decreasing with increasing latitude (P<0.001). This trend is consistent with the Shannon index and richness of plants (P<0.001) but contrary to the overall soil fungal diversity trends (P<0.001). Random forest model analysis identified the plant Shannon index is the primary factor influencing the Shannon index of soil phytopathogenic fungi (P=0.001). Structural equation modeling confirmed a significant positive correlation between the soil phytopathogenic fungi diversity and plant diversity (P<0.001), and climate factors and soil physicochemical properties may regulate plant diversity by affecting soil phytopathogenic fungi (P<0.05). The network topological index and latitude regression analysis indicated that interactions between plants and soil phytopathogenic fungi intensify with increasing latitude, with significant increases in specialization and modularity (P<0.05). This suggests that the suppressive effect of soil phytopathogenic fungi on plant diversity strengthens with latitude, thereby influencing the latitudinal distribution patterns of plant diversity. These findings highlight the crucial role of plant diversity in the distribution of soil phytopathogenic fungi and suggest that the threat posed by these fungi to forest health varies with latitude.