Fusarium in banana from Ecuador: A morphological, molecular and pathogenic study as a control strategy

Fusarium oxysporum f. sp. cubense is associated with wilting in banana cultivation. The soil-dwelling phytopathogenic fungus has caused devastating consequences worldwide. The races that affect bananas are 1, 2 and 4, the latter very feared because of the epidemics caused since its identification, and because to date an effective control against the pathogen has not been determined. Therefore, the objective of the research was to isolate and characterize morphologically using four culture media, and molecularly the fungus in order to evaluate its pathogenicity with in vitro and greenhouse tests. 20 symptomatic samples were collected from an apple variety banana plantation. Subsequently, isolations were made from vascular tissue. The morphological identification of the isolates obtained was decisive to use a single strain for subsequent analysis and trials due to the similarity of the isolate's strains. These strains were characterized by a cottony white mycelium that gradually changed to purple. Microscopy identified macroconidia, microconidia and chlamydospores. Molecular analysis was performed through the genes: translation elongation factor TEF1α, and Rpb2. The strain (Fus banana) was identified as F. oxysporum f. sp. cubense, accessions TEF1α (PV682586), Rpb2 (PV682587). The results were expressed in terms of incidence and severity. The medium malt extract registered a higher incidence reaching 99%. Regarding the distribution of severity, a progressive pattern in the intensity of symptoms was observed. The results obtained constitute consistent scientific support for future studies that are oriented towards the development of reliable diagnostic tools, the evaluation of pathogenicity in banana materials and the design of integrated management strategies against this pathogen with high economic and phytosanitary impact.