Genetic diversity in Fusarium verticillioides populations recovered from corn plants in Khuzestan using vegetative compatibility groups

Samples of infected corn plants grown in different parts of Khuzestan province (Andimeshk، Dezful، Shoush، Shoushtar and Mollasani) were collected in 2006. One hundred and thirty five isolates of F. verticillioides were recovered from different parts of the plants (root، crown، stem، male inflorescence and cob) by using Nash & Snyder medium. Seventy five isoletes were selected for the vegetative compatibility groups (VCGs) studies. Nit mutants were generated on two different media containing 3 and 5% KClO3 (Minimal medium=MMC)، (Potato dextrose agare =PDC) and Czapeck medium containing 3% KClO3 (Czapeck). Collectively 668 nit mutants were obtained. Nit mutants were classified into 3 phenotypic classes (nit1، nit3 and NitM) according to their colony morphology and growth on basal medium supplemented with one of the sodium nitrate، sodium nitrite، hypoxantine or ammonium tartarate with the frequencies of 42. 66، 23. 64 and 33. 7% respectively. Nit mutants were used to force heterokaryon formation. All of the isolates were grouped in to 34 VCGs، of which، the largest one had 7 members and 13 VCGs had only one member each. Isolates from different areas formed several VCGs. For instance of all the VCGs identified، 6 were from Andimeshk، 6 from Dezful، 8 from Shoush، 7 from Shoushtar and 7 from Mollasani. Of all the 34 identified VCGs ten were common in more than of one area and the rest occurred only in their site of origin. In this study no special relationship was observed between VCGs and the geographic origin of the isolates. These results indicate a high level of genetic diversity in populations of F. verticillioides associated with corn plants in Khuzestan province.