Olea europaea fungal microbiota Metagenome

The fungal microbiome was investigated in olive drupes from four different localities and cultivar, infected and non-infected by the olive fruit fly (OFF), Bactrocera oleae. Regardless of the OFF infestations, results showed the existence of a typical olive fungal microbiome in all investigated localities with the prevalence of the genera Aureobasidium, Cladosporium, and Alternaria. Furthermore, the majority of fungi identified in olives overlapped with those previously described from the olive fruit fly suggesting a shared evolutionary process of olive and B. oleae, which is a typical host-specific insect. Olive fruit fly infestations caused a general reduction of the fungal diversity, a higher quantity of the total DNA and an increase of taxa that remained unidentified or with unknown roles. On the other hand, the most abundant taxa typical of the olive microbiome were not significantly influenced by the insect and showed different trends in the different sampling locations. Overall, obtained data suggests that OFF infestations led to imbalanced fungal communities with the growth of taxa that are usually outcompeted. This phenomenon named dysbiosis in human and other mammalians has never been described before for plants. While it was difficult to establish a cause-effect link between fly and specific fungal taxa it is clear that the fly alters the natural microbial balance and this is likely implicated in the reduced quality of the olive oil from infested olives.