<b>Phyllosphere pathogen</b>

Plant growth trade-offs related to the colonization potential of pathogenic fungi. However, the potential co-variation between plant functional diversity and the diversity of pathogenic fungi colonizing plant leaves has been largely overlooked in previous studies, posing a challenge to our comprehension of the relationship between plant phyllosphere pathogenic fungi and plant growth trade-offs. In this study, we collected fresh phyllosphere samples from 84 individuals of 12 dominant species in the Mt. Huangshan Forest dynamics plot. We quantified pathogenic fungi in these samples using high-throughput sequencing technology and functional prediction. Additionally, we employed the ‘Stratefy’ to calculate plant CSR ecological strategies. Our findings identified Mycosphaerellaceae and Teratosphaeriaceae as the dominant pathogenic fungi in the subtropical forest. Hosts, rather than habitats, exerted a greater influence on phyllosphere pathogenic fungi. Utilizing multiple regression linear models and null models, we delved into the impacts of environmental factors on pathogen diversity and the mechanisms governing phyllosphere microbial community assembly. The outcomes underscored that phyllosphere microbial diversity is influenced by leaf pH, C: N, and dry weight. However, stochastic processes predominantly shaped the spatial variation of phyllosphere microbial community composition, primarily driven by neutral processes. To investigate whether fast-growing species are more susceptible to pathogens, we scrutinized the relationship between ruderals’ percentage (R selection) and pathogen diversity through linear regression. The results unveiled a significant negative correlation between R-selection and pathogen diversity. Finally, we quantified the extent to which different levels of species taxonomy explained phyllosphere pathogenic fungal diversity and leaf functional traits using linear mixed-effects analysis with variance partitioning. These analyses revealed that levels of family explained the highest degree of variation. Overall, our results suggest that life history trade-offs in plant-pathogen interactions may significantly influence the mechanisms contributing to equilibrium between species in this community. This lays a foundation for further research on the effects of phyllosphere pathogenic fungi on the coexistence of plant species.