Abstract
Twelve species from six fungal genera were found to be associated with Sorghum (Sorghum bicolor [L.] Moench) grain samples collected from different markets at three main regions of Saudi Arabia. The average frequencies of the most common genera were Aspergillus (10.3%), Penicillium (9.8%), Fusarium (9.5%) and Alternaria (7.7%). Thirteen isolates of Aspergillus flavus were screened by HPLC for their ability to produce aflatoxins (AFs). The percentage of aflatoxigenic A. flavus isolates was 46.2%. Six isolates produced AFs, at concentrations ranging 0.0-6.1 mu g/ml. Inter simple sequence repeat (ISSR) and random amplified polymorphic DNA (RAPD) molecular markers were used to genetically characterize strains of A. flavus and to discriminate between the aflatoxigenic and non-aflatoxigenic isolates. RAPD and ISSR analysis revealed a high level of genetic diversity in the A. flavus population, which was useful for genetic characterization. The clustering in the RAPD and ISSR dendograms obtained was unrelated to geographic origin. The RAPD and ISSR markers could not discriminate between aflatoxigenic and non-aflatoxigenic isolates, but the ISSR primers were somewhat better.