A Mycological Reappraisal of the Phylloplane Microbiome

Abstract

The phylloplane is a highly varied, ecologically active microbial surface that hosts various fungal communities that can determine plant health, physiology, and ecosystem functionality. Such epiphytic fungi are both resident taxa that can potentially go through their life cycle on the leaf surface and transient species that come with environmental vectors. The heterogeneous microhabitat of the leaf that contains stomatal grooves, epidermal folds, cuticular chemistry, and nutritional hotspots created by the exudate creates selective niches that promote fungal assembly and functional differentiation. Phylloplane fungi enhance the host vitality by several mechanisms, such as nutrient absorption, hormone production, phytopathogen resistance, and systemic resistance. Some of these epiphytic fungi, such as Trichoderma, Aureobasidium, and Pseudozyma, are good bio-controlling agents since they are resource competitors, secrete antimicrobial chemicals, or alter the plant immunological pathways. Their ecological activities involve the control of senescence, leaf-surface interaction, decomposing processes, and influencing the nutrient cycle. The current review is a summary of the existing knowledge on phylloplane fungal diversity, colonization, ecological associations, and functional importance, through which we aim to develop the findings that will add to our knowledge of leaf-associated microbiomes.