Aislamiento, caracterización e identificación de hongos filamentosos asociados con síntomas de cáncer en plantaciones de pitahaya (Hylocereus spp.).

Abstract

The objective of this research work was to isolate, characterize, and identify filamentous fungi associated with cancer symptoms in pitahaya cladodes (Hylocereus spp.) in Pedro Vicente Maldonado canton, in Pichincha province. The samples were received at the Phytopathology laboratory of the Faculty of Natural Resources (FRN) for disinfection, seeding, isolation, and obtaining pure cultures of the isolated fungal microorganisms. In the morphological and cultural characterization, characters such as color, colony front and back, medium elevation, margin shape, and mycelial growth rate (MGR) were registered. Microscopic characterization registered the number of spores and spore size. For molecular characterization, mycelium extraction and maceration, deoxyribonucleic acid (DNA) extraction, polymerase chain reaction (PCR), electrophoresis, and sequencing were performed. Characterization of the pathogenicity of fungal isolates was carried out in the FRN greenhouse, where healthy pitahaya cladodes were inoculated using two methods: wounded and unwounded. The filamentous fungi identified were Lasiodiplodia theobromae, Fusarium oxysporum, Daldinia sp., and Diaporthe sp., which were identified and characterized culturally, morphologically, and culturally. Of the inoculated strains, those that could be recovered in the re-isolation were Lasiodiplodia theobromae, Fusarium oxysporum, and Diaporthe sp., thus fulfilling the pathogenicity tests and demonstrating the potential for damage at the cladode level in pitahaya. This is the first study on diseases at the level of the pitahaya phylloplane in Ecuador that reports Lasiodiplodia theobromae, Fusarium oxysporum, and Diaporthe sp. as causes of symptoms associated with cancer in this crop of growing importance in our country.