Characterization of leaf-associated fungi from olive cultivars with different levels of resistance to anthracnose

• Autor(a) principal: Bahri, Hamdi
• Data de Publicação: 2019
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10198/23061
• topic: Olea europaea; Colletotrichum; Endophytes; Epiphytes; Host specificity; Domínio/Área Científica::Ciências Agrárias::Biotecnologia Agrária e Alimentar

Olive anthracnose, caused by Colletotrichum spp., is one of the most damaging fruit diseases in olive crops worldwide. Their control is very difficult and relies mostly on the use of copper-based fungicides. The plant-associate fungal community has been increasingly recognized for playing an important role in plant health. Thus, in this work, the leaf-associated fungi of olive cultivars with different levels of resistance to anthracnose were characterized to identify potential fungi implicated in host resistance. A culture-dependent approach was used to assess both epiphytic and endophytic fungal communities of leaves of olive cultivars Madural (susceptible to anthracnose) and Cobrançosa (moderately tolerant), and the isolates obtained were identified by rRNA sequencing. Overall, Ascomycota phylum and Aureobasidium genus were the most dominant, being epiphytes significantly more diverse and abundant than endophytes. Among the genera identified in the most-resistant cultivar, Aspergillus and Pseudocercospora were the most frequently isolated within epiphytic and endophytic communities, respectively; whereas in the susceptible cultivar, Aureobasidium and Didymocyrtis, were the most frequently isolated within epiphytic and endophytic communities, respectively. The host plant (at cultivar level) had a structuring effect on the composition of fungal communities of leaves, being this effect greater on epiphytes than on endophytes. Thus, it is likely that each cultivar selects specific fungal taxa, which may lead to specific feedbacks on fitness of plant genotypes. In total, 20 fungal taxa (15 endophytes and 5 epiphytes) were responsible for more than 50% of the dissimilarity found on fungal community between cultivars. Among these, three taxa from the Phaeomoniellaceae family and one unidentified fungus, were the most discriminant. Their functional role needs to be studied in the future, because they might be important in conferring host plant resistance towards anthracnose.