Morphological and Molecular Characterization of Fungal Species Associated with Fusarium oxysporum f.sp. cubenese (Foc) in Gatundu North, Kenya

Banana (Musa spp.) is the most produced fruit globally as a food security crop and a rich source of nutrients. It is a staple and a source of income for millions of people in the tropics and southern tropics. The current and future production status of banana is under severe threat from Fusarium wilt of banana (FWB), also called Panama disease, caused by Fusarium oxysporum f.sp. cubense (Foc). There are many fungal species in the banana rhizosphere associated with the pathogenicity of Foc. This study characterized the fungi in the microbiome of bananas from three wards in Gatundu North, Kiambu County. Six hundred and twelve soil samples showing symptoms of FWB were collected from the sampling sites. Ninety-eight (98) fungal species were isolated using serial dilution on potato dextrose agar (PDA) and morphologically characterized. DNA of each species was extracted using the internal transcribed spacer (ITS) regions of ribosomal DNA (rDNA) (ITS1 and ITS4) and sequenced using Sanger sequencing. Comparison of the sequences to the GenBank database was performed using Basic Local Alignment Search Tool and the phylogenetic tree was constructed using the neighbor-joining method of the MEGA X software v.6.1. The characterized isolates were of the following genera: Fusarium, Penicillium, Paecilomyces, Rhizoctonia, Trichoderma, Simplicillium, Epicoccum, Curvularia, Alternaria, Bipolaris, Exserohilum, Setosphaeria, Cochilobolus, Syncephalastrum and some unidentified species. The study reveals fungal species associated with Foc pathogenesis in bananas in Gatundu North, Kiambu County, Kenya, and suggests a potential for the development of biocontrol strategies in the management of Panama disease.