Ecological roles of leaf-inhabiting fungi and their host-associated predictors: a review

Plant microbiome refers to the diverse communities of microorganisms, including bacteria, fungi, viruses, and archaea, that inhabit plant organs and surfaces. Plant microbiomes contribute to nutrient acquisition, plant immunity, stress resilience, and overall plant fitness. Among these microorganisms, leaf-associated fungi, encompassing saprotrophic, endophytic, and pathogenic species, play essential roles in plant and ecosystem functioning. This review provides an overview of the current knowledge on the functional roles of leaf-associated fungi and how plant functional traits and host identity shape these fungal communities. The functional identity of many fungi is dynamic, shaped by ecological plasticity that allows shifts in lifestyle across temporal and spatial gradients. Our synthesis highlights that plant structural, chemical, and phenological traits expressed within species-specific evolutionary contexts act as ecological filters influencing fungal colonization, community composition, and functional strategies. Thus, the ecological roles of leaf-associated fungi emerge from the interaction among plant phenotype, host identity, and environmental conditions. Future studies should utilize culture-dependent and culture-independent approaches to fully uncover the ecological roles and diversity of leaf-associated fungi. Such studies will provide valuable insights for conservation and sustainable ecosystem management amidst global environmental changes.