Potential application of endophytes in the management of olive fruit fly and anthracnose

• Autor(a) principal: Sdiri, Yosra
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10198/24257
• topic: Biocontrol; Aureobasidium pullulans; Sarocladium summerbellii; Bactrocera oleae; Colletotrichum acutatum; Volatile compounds; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

Olive fruit fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae), and olive anthracnose, mainly caused by Colletotrichum acutatum, are considered key biotic constrains of olive crop worldwide. Strategies employed for controlling this pest and disease are mostly based on the use of insecticides and copper-based pesticides, respectively, which is not compatible with sustainable production systems. This work aims to study the effect of two endophytes, previously isolated from olive tree, namely Aureobasidium pullulans and Sarocladium summerbellii on the behavior (i.e. attractiveness or repellence) and preference for oviposition of B. oleae, as well as on anthracnose infection, by using in vitro and in vivo (detached fruits) assays. Aureobasidium. pullulans-mediated changes in olive fruit volatile organic compounds (VOCs) and their consequences for anthracnose disease development were also evaluated. The tests performed by multi-choice olfactometer showed that both endophytes did not exert a repellent or attractive effect against mature gravid B. oleae female’s. Similarly, females did not showed preference to oviposit in olives inoculated with endophytes versus non-inoculated. Among the two endophytes tested, only A. pullulans inhibited significantly the growth (up to 1.3-fold), sporulation (up to 5.9-fold) and spore germination (up to 3.5-fold) of C. acutatum in relation to the control (C. acutatum). Similarly, in inoculated olive assays, only A. pullulans was able to reduced significantly progress curve for incidence (up to 10-fold) and severity (up to 35-fold) of anthracnose, as well as both sporulation (up to 90%) and germination (up to 70%) of C. acutatum, in comparison with olives inoculated solely with C. acutatum. Gas chromatography–mass spectrometry analysis of olives inoculated with A. pullulans+C. acutatum and controls (olives inoculated with C. acutatum, A. pullulans or tween) led to identification of 29 VOCs, belonging to 10 different chemical classes, being alcohols the most diversified and abundant ones. The volatile profile of A. pullulans + C. acutatum revealed quali- and quantitatively differences from the controls, in particular due to the production of (z)-3-hexen-1-ol and acetic acid, hexyl ester. These findings provide new viable possibilities of controlling olive anthracnose using the endophyte A. pullulans and/or their VOCs. These volatile inhibitory metabolites should be further tested against anthracnose.