Submitted to: Mycopathologia
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/25/2005
Publication Date: 1/1/2006
Citation: Baird, R.E., Trigiano, R.N., Windham, G.L., Williams, W.P., Kelly, R., Abbas, H.K., Moulton, J.K., Scruggs, M.L. 2006. Comparison of aflatoxigenic and nonaflatoxigenic isolates of Aspergillus flavus using DNA amplification fingerprinting techniques. Mycopathologia. 161:93-99. Interpretive Summary: Aspergillus flavus is a fungus that is commonly found in corn grain in the Southeast and can produce aflatoxins which are toxic to humans and livestock. The best method for controlling this fungus is the use of resistant corn genotypes. To identify resistant plants, corn ears must be inoculated with the fungus in the field. It would be helpful if a technique was available to differentiate between fungal strains placed in the ear by researchers and those found naturally in the field. Also, a rapid technique to differentiate between strains of the fungus that produce aflatoxins and strains that do not produce aflatoxin would be helpful to researchers. In this study, two lab based techniques that look for differences in fungal DNA were evaluated. One technique was able to distinguish between aflatoxin producing fungal strains and strains that do not produce aflatoxin. This technique may be helpful to researchers in identifying corn plants that are resistant to the fungus and limit aflatoxin production.
Technical Abstract: Aspergillus flavus is a filamentous fungus that produces mycotoxins in many food and feed crops, such as maize (Zea mays L.). Isolates were analyzed for toxin production by nucleic acid profiles in an attempt to differentiate toxigenic from atoxigenic isolates. A total of 41 toxigenic and 34 atoxigenic isolates were included in the study. The isolates were evaluated initially using DNA amplification fingerprinting (DAF) without clear resolution of the groups. The additional procedure, arbitrary signatures from amplification profiles (ASAP), which involved a dual-step arbitrary primer based amplification of DAF products, distinguished toxigenic from atoxigenic isolates. Toxigenic Aspergillus spp. isolates formed a monophyletic group in the majority of most parsimonious trees recovered, whereas ingroup atoxigenic isolates were only weakly differentiated. These data suggest that toxin production represents an evolutionary novelty within these fungi. Identification of toxigenic isolates of A. flavus present on maize plants using ASAP would reduce labor intense costs and potentially lead to faster determination of resistant cultivars in breeding efforts.