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Population biology of Fusarium oxysporum associated to banana in Ecuador

Freddy Magdama: Escuela Superior Politécnica del Litoral

<div>Ecuador is a leader in banana exports, however, epidemiological studies of <em>Fusarium oxysporum</em> f.sp. <em>cubense </em>(<em>Foc</em>) are still lacking. Assessing the evolution and diversity of pathogenic and nonpathogenic populations of <em>F. oxysporum</em> associated to banana within an ecological context would reveal new information for the management of <em>Foc</em> tropical race 4 (<em>Foc</em>TR4) threatening global banana production. A collection of 460 isolates was used to perform comparative phylogenetic analyses based on TEF, IGS and RPB1 gene regions. Further analyses included pathogenicity test, VCGs, validation of <em>Foc</em>TR4 detection methods and presence of putative effector genes. Our results suggest that <em>Foc </em>populations from Ecuador are clonal and associated with VCG-0120, indicating a single introduction. <em>Foc </em>is present as endophyte in the roots of Cavendish in areas previously used for the production of ‘Gros Michel’. Three out of the four markers currently available in the literature were not reliable for FocTR4 detection and generated false positive PCR reactions. Effector SIX genes, putatively linked to pathogenicity, were found in Ecuador <em>Foc</em> populations but also in nonpathogenic <em>F. oxysporum</em>, suggesting a broader role of these genes in plant-microbe interactions. We propose the consideration of <em>F. oxysporum</em> endophytes as key constituents in the evolution of the species and highlight the importance of understanding its true ecological niche for better disease control and risk management.</div>