Microbial Communities on Aerial Surfaces: Disease Impact and Resource Dynamics

Microbial communities on aerial host surfaces, like mushroom caps and leaves, play vital roles in host health. These communities thrive on resources provided by the host, which include sugars, amino acids, and secondary metabolites that are constitutively expressed. Less investigated on aerial host surfaces is how stress and disease affect these resources – both in composition and type– and subsequently the associated microbiome, and is what this study explores utilizing mushroom caps and tomato leaves. In mushrooms, caps symptomatic for bacterial blotch disease had significant enrichment of Pseudomonads and rarer species across over 100 genera, while asymptomatic mushroom saw significantly less enriched species, but those that were enriched included beneficial microbes such as Pseudomonas putida. In tomato, we found that leaf surface metabolites change during stress responses, and that these changes are specific to the stress elicitor, regardless if the same hormonal pathway is considered elicited. Furthermore, we found that disease in one part of the plant can alter the leaf surface metabolites on unaffected leaves, and these changes directly improve the pathogen’s establishment and colonization in that new leaf. Understanding these dynamic interactions between host resources, microbes, and disease is crucial for promoting host health and resilience.