Submitted to: Plant Disease
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/17/2001
Publication Date: N/A
Citation: Interpretive Summary: Aspergillus flavus may infect seeds of peanuts, cotton, corn and tree nuts and contaminate them with aflatoxins, which are potent hepatoxic, carcinogenic metabolites that pose a significant health hazard. There is a need to understand the genetic structure and diversity of Aspergillus flavus populations in crop fields, particularly as this relates to the distribution of important fungal attributes such as aflatoxin production, sclerotium formation, pathogenicity/virulence, and competitive ability. This research was undertaken to assess the ability of a DNA probe to correctly identify Aspergillus flavus strains belonging to genetically distinct populations from a peanut field in southern Georgia. The results show that multiple strains belonging to the same population produced identical DNA fingerprints. Genetically distinct fungal strains represented by a single isolate each produced unique DNA fingerprints. The pAF28 DNA probe provides a reliable means of elucidating the population genetics of Aspergillus flavus. Increased knowledge of the population biology of this pathogen of oil seeds is likely to lead to better management of disease in agricultural systems.
Technical Abstract: The ability of a species specific DNA probe pAF28 to correctly match 75 A. flavus strains isolated from a peanut field in Georgia with one of 44 distinct VCGs was assessed. Multiple strains belonging to the same VCG typically produced identical DNA fingerprints with the exception of VCG 17 and VCG 24 which contained strains that showed 83 and 87% similarity, respectively. Aspergillus flavus isolates sharing more than 80% of the fragments are recognized as belonging to the same DNA fingerprint group. All VCGs represented by a single isolate produced unique DNA fingerprints. The results provide further evidence that the pAF28 probe is able to distinguish A. flavus VCGs based on DNA fingerprints and can be used to predict the approximate number of VCGs in a sample population. The DNA probe also hybridized strongly and displayed multiple and distinct bands with other species in Aspergillus section Flavi: A. bombysis, A. caelatus, A. pseudotamarii and A. tamarii. Only a few weak bands could be detected in repeated tests with Aspergillus nomius. While individual strains representing Aspergillus species in section Flavi produced DNA fingerprints with multiple bands, the banding patterns could not be used to classify these strains according to species.