<b>Molecular functional diversity of foliar endophytic fungi and their contributions to seedling survival in a subtropical forest</b>

We found that FEF transcript diversity was strongly associated with host divergence time and maximum height, and FEF functions significantly enhanced seedling survival through fitness-related and niche-related processes. Among these FEF functions, gene ontology (GO) terms with high host-phylogeny dependence enhance seedling survival through fitness differences associated with multi-organism interactions, while those with high host-trait dependence enhance seedling survival through niche differentiation related to basic life processes. Our findings establish a bridge between microbial functional genomics and modern coexistence theory in natural forests.