Molecular identification of Fusarium species in commercial vanilla and crop wild relatives in Colombia

Abstract

Vanilla is an economically important crop for low-lying humid tropical regions, but cultivated plants face serious phytosanitary problems. Fusarium wilt is a devastating disease affecting vanilla crops, caused by the fungal pathogens Fusarium oxysporum f. sp. vanillae (Fov) and F. oxysporumf. sp. radicis-vanillae (Forv), part of the F. oxysporum species complex(FOSC). We characterized 29 fungal isolates from a vanilla crop and crop wild relatives (CWR) using molecular (EF1-α and ITS-rRNA loci) and morphological traits. Fusarium was the predominant genus, followed by Colleto-trichum and Clonostachys. Four Fusarium species were identified:F. oxysporum (37.9%), Fusarium solani (20.7%), Fusarium pseudocircina-tum (13.8%) and Fusarium concentricum (10.3%). The latter three species were isolated only from CWR and may represent latent pathogens. Fov was isolated from both the crop and CWR, while a Forv-affiliated isolate was also found in a vanilla crop, marking the first report in the neotropical region. TheEF1-α locus provided greater genotype resolution, as well as having refer-ence sequences for Forv. However, the fungal barcode ITS locus is widely applied. We recommend the continued use of both loci for Fusarium diagno-sis in vanilla to facilitate early detection and the development of effective integrated crop management strategies. Más...