Fifteen non-aflatoxigenic strains of Aspergillus flavus, representing a wide range of geographic regions of Iran (six provinces including Fars, Ardebil, Guilan, Golestan, Kerman and Semnan) and vegetative compatibility groups (VCGs) were collected from corn (Zea mays L.), peanut (Arachis hypogaea L.) and pistachio (Pistachia vera L.) soils and kernels, and were screened for the presence of aflatoxin biosynthesis genes in relation to their capability to produce aflatoxins, targeting the regulatory genes afIR and aflJ, the structural genes aflT, pksA,ver-1, omtA, omtB, aflD, ordA, verA, norA, hypA, norB, cypA, sugar utilization gene glcA and flanking region gene C3 (5\\\\\\\' end) by PCR method. This process resulted in grouping of A. flavus strains into twelve different amplification patterns (I-XII), characterized by 10-14 different DNA bands. Our results reveal that aflatoxin biosynthesis regulatory genes (aflR and aflJ) and the structural gene hypA are more important genes to detect non-aflatoxigenic strains of A. flavus. For non-aflatoxigenic strains of A. flavus, no relationship was observed between the deletion pattern and geographic origin and/or VCG; which may indicate that non-aflatoxigenic strains of A. flavus did not originate independently at each locality. It is concluded that the aflatoxin gene cluster variability existing in the non-aflatoxigenic popula- tions of A. flavus can be useful for understanding the toxicological risk as well as the selection of biocontrol agents.

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