Fungal community diversity in leaves from two olive tree cultivars dissimilarly susceptible to anthracnose and to olive fruit-fly

Abstract: Aiming to glimpse a biocontrol management approach anchored to the olive tree-associated resident fungal microbiota, in this work we studied the diversity, structure, and composition of epiphytic and endophytic fungi inhabiting in and on leaves from two important NE Portuguese cultivars (Cobrançosa and Madural). These cultivars exhibit dissimilar susceptibilities related to anthracnose disease and to a pest, the olive fruit fly Bactrocera oleae, being cv. Madural more susceptible to anthracnose and more infested by the fly than cv. Cobrançosa. Through a culture-dependent approach, and by sampling leaves (from the inner and outer canopy) from five trees of an organic orchard, we obtained 203 isolates corresponding to 161 taxa. A comparison of epiphytic and endophytic fungal communities, at the tree level, revealed significant differences in species richness and diversity. Epiphytes were most rich and diverse (6 subphyla, 11 classes, 21 orders and 36 families) when compared to endophytes (5 subphyla, 10 classes, 15 orders, 27 families). In terms of composition, the fungi community from leaves of cv. Cobrançosa was different than that from cv. Madural, markedly regarding the epiphytic community. On the other hand, the endophytic community was not different in terms of composition neither between cultivars, nor by canopy location. Implications of these findings for the use of endophytic and/or epiphytic fungi in these two cultivars are discussed, in the light of possible biocontrol practices to manage both anthracnose (Colletotrichum spp.) and the olive fruit-fly.