Investigation on genetic diversity of Fusarium verticillioides isolated from corn using vegetative compatibility groups and relation of VCGs to the pathogenicity

Forty isolates of Fusarium verticillioides were recovered from corn seeds using Nash & Snyder media. Seed samples had been collected from the major producing area in Khuzestan and Ardabil provinces. Isolates were tested for their pathogenicity on the corn-detached stalks. Results revealed that all isolates were pathogenic to the plant samples tested. Four hundred and twenty nitrate non-utilizing mutants were generated from corn seeds isolates. Media used for generation of nit mutants were potato dextrose agar (PDA), minimal & Czapeck agar amended with 3% chlorate potassium. Nit mutants were divided into three phenotypic classes (nit1, nit3 and nitM) based on their growth on the medium containing different nitrogen sources. From the tested isolated 265, 95 and 95 nit isolates, respectively of nit1, nit3 and nitM, were generated. Nit mutants were used to force heterokaryon formation to determine distribution of VCGs and their relation to pathogenicity and geographic origin. For corn seeds, isolates, 39 VCGs were determined. Of these, 38 were single and one was single member VCGs. Specific relation was not observed between VCGs and geographic origin of the isolates in this study. It means that genetic diversity among population of F. verticillioides is very high.