Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 25, 1998
Publication Date: N/A
Interpretive Summary: Aspergillus parasiticus attained notoriety when it was shown to contaminate peanuts with aflatoxins which are potent hepatotoxins and carcinogens. The fungus can also infect corn and is common to tropical and subtropical soils but is only rarely isolated from northern latitudes and was only recently recorded from soils within the Corn Belt. Here we report isolating the first A parasiticus population from field soil in Illinois. This population is comprised of numerous genetically distinct individuals, all producing substantial quantities of aflatoxins, as is reported for A. parasiticus populations from warmer regions. This information provides the corn industry with a better understanding of the potential aflatoxin-producing fungal populations in the Midwestern Corn Belt.
Technical Abstract: Aspergillus parasiticus Speare was isolated from direct platings of soil (Bloomfield sand) sampled from a corn field near Kilbourne, IL. Fewer than 5 colony forming units of A. parasiticus were recorded from 0.5-g quantities of soil that were added to Botran medium and incubated at 37.5 C. Sixty isolates, each one from a separately collected soil sample, were examined for ability to produce sclerotia, aflatoxins, and submitted to DNA fingerprinting. Pst I digests of total genomic DNA from each isolate were probed using the pAF28 repetitive sequence. Among 60 isolates analyzed, 45 distinct DNA fingerprint groups were identified (each group sharing less than 80% pAF28 band similarity). A. parasiticus genotype number 8 represented 12% of the sample population. The 70% genotypic diversity of the A. parasiticus population was only marginally lower than the 84% genotypic diversity recorded earlier for a population of Aspergillus flavus isolates from the same soil samples. Sclerotia were produced by 83% of the A. parasiticus genotypes during dark incubation (25 C). All isolates of A. parasiticus produced aflatoxin B1B2 and G1G2, while only 42% of the A. flavus genotypes isolated from these soils produced aflatoxins.