Comparative study of the major Iranian cereal cultivars and some selected spices in relation to support Aspergillus parasiticus growth and aflatoxin production.

BACKGROUND Aflatoxins are toxic fungal metabolites enable to contaminate a wide range of natural substrates. This contamination can be host-specific for different plant species. In this study, the ability of a toxigenic Aspergillus parasiticus to produce various aflatoxins on major Iranian cereals was evaluated with special focus on plant susceptibility to toxin production at cultivar level. METHODS Aspergillus parasiticus cultured on major Iranian cereal cultivars and some selected spices was incubated in shaking condition at 28 masculineC for 6 days. The concentration of aflatoxins B1 and total (B1, B2, G1 and G2) was measured by thin layer chromatography. RESULTS The amounts of aflatoxin B1 produced on maize, wheat and rice cultivars were in the ranges of 1.0-33.9, 41.9-193.7, and 39.1-82.3 microg/g fungal weight, respectively. Interestingly, genetically modified Bacillus thuringiensis rice (GM rice) of Tarom Molaii cultivar examined for the first time in this study showed less susceptibility to aflatoxin production in comparison with its normal counterpart (P less than 0.05). The mean of aflatoxin production on maize cultivars was less than both wheat and rice cultivars that indicates considerable resistance of maize to aflatoxin compared with two other cereals. Unlike to Cuminum cyminum, both Helianthus annuus and Carum carvi seeds were highly resistant to aflatoxin production. CONCLUSION These results indicate that inter- and intra-species differences exist in susceptibility of the major Iranian cereals as well as spices tested to A. parasiticus growth and aflatoxin production. Further studies are recommended to determine resistance markers of selected cultivars of Iranian cereals.