Characterisation and Divergence of Fusarium Species in Certain Varieties of Zea mays L.

An experiment was conducted to characterize and evaluate the diverse Fusarium species associated with some varieties of Zea mays L. Root samples of thirteen maize varieties were collected in three replicates from different seed multiplication fields in International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, Ibadan. Isolation of Fusarium species from the samples were done by inoculating five cut sections of 3mm of the maize roots on sterilized Potato Dextrose Agar (PDA) medium for fungal growth and all plates were incubated for 5 days at 25 ?C. The fungal isolates were sub-cultured and single spore isolation was done to obtain pure culture. Morphological characterization of the isolated Fusarium species was done following standard procedures. Molecular identification was conducted by PCR assay using ITS1 and ITS4 primers. The Fusarium species were analyzed by DNA sequence. Data obtained were subjected to analysis (ANOVA) using Generalized Linear Model Procedure (GLM) of statistical analysis software (SAS). Means were separated using Duncan?s Multiple Range Test (DMRT) at p ? 0.05. Thirty-nine Fusarium isolates (all of which were four species), were obtained from the thirteen maize varieties. These include thirty isolates (three strains) of F. verticillioides from all the thirteen maize varieties, four isolates (two strains) of F. fredkrugeri from four varieties, three isolates (two strains) of F. oxysporum from three varieties and two isolates (two strains) of F. solani from two maize varieties. Fusarium verticillioides was the predominant species with an incidence of 76.9% followed by F. fredkrugeri (10.3%), F. oxysporum (7.7%) and F. solani (5.1%). Cultural characteristics of some isolates of the same strain from different maize varieties were not the same. Radial growths of the F. verticillioides, F. oxysporum, F. fredkrugeri and F. solani differed significantly (p?0.05) at the different days of incubation. Macroconidia as well as the microconidia of isolates of different species differed significantly in length, and also in breadth (p?0.05). Macroconidia as well as the microconidia of some isolates of the same species from different maize varieties also differed significantly in length, as well as in breadth (p?0.05). On agar, sometimes growth performance of one particular Fusarium strain obtained from different maize varieties can differ. This could be the first reported case of Fusarium fredkrugeri isolated from maize roots.