Localized reshaping of the fungal community in response to a forest fungal pathogen reveals resilience of Mediterranean mycobiota.

Mediterranean forests are facing the impact of pests such as the soilborne Phytophthora cambivora, the causalagent of Ink disease, and this impact is made more severe by global changes. The status and resilience of thesoil microbial ecosystem in areas with such a disturbance are little known; however, the assessment of the microbialcommunity is fundamental to preserve the ecosystem functioning under emerging challenges.Weprofilesoil fungal communities in a chestnut stand affected by ink disease in Italy using metabarcoding, and couple highthroughputsequencing with physico-chemical parameters and dendrometric measurements. Since the site alsoincludes an area where the disease symptoms seem to be suppressed, we performed several analyses to searchfor determinants that may contribute to such difference. We demonstrate that neither pathogen presence nortrees decline associatewith the reduction of the residing community diversity and functions, but rather with microbialnetwork reshaping through substitutions and new interactions, despite a conservation of core taxa. Wepredict interactions between taxa and parameters such as soil pH and C/N ratio, and suggest that disease incidencemay also relate with disappearance of pathogen antagonists, including ericoid- and ectomycorrhizal(ECM) fungi. By combining metabarcoding and field studies, we infer the resilient status of the fungal communitytowards a biotic stressor, and provide a benchmark for the study of other threatened ecosystems.