Submitted to: U.S. Pistachio Industry
Publication Type: Other
Publication Acceptance Date: December 30, 2008
Publication Date: March 1, 2009
Citation: Hua, S.T. 2009. Molecular Technique to Fingerprint Aspergillus flavus Causing Aflatoxin Contamination in Food. U.S. Pistachio Industry. Interpretive Summary: Aspergillus flavus has a worldwide distribution. It is an important fungus which causes disease in human and crop plants due to the production of numerous conidia dispersed by air movement and possibly by insects. In addition it produces the most potent natural carcinogen known, i.e. aflatoxin (AF). A. flavus has no known sexual stage; consequently, most studies on its genetic variability have been made mainly by characterizing isolates based on vegetative compatibility group (VCG). Complementary nitrate-nonutilizing (nit) mutants are commonly used to identify compatible isolates. VCG analysis becomes cumbersome for genetic analysis involving large populations because it requires pairing each new mutant strain with a representative of each VCG determined for that population while eliminating isolates that are self-incompatible. Alternative Techniques has to be developed for accurate identification and trace individual strain of A. flavus.
Technical Abstract: A retrotransposon, AFLAV (A. flavus retrotransposon), has been recently characterized in A. flavus. Complete DNA sequence of 7784 bp containing the AFLAV has been submitted to GenBank (accession number AY485785). Multicopies of this transposon are dispersed in the chromosomes of A. flavus. PCR primers derived from AFLAV can provide a rapid molecular method to fingerprint population of A. flavus collected from pistachio orchard or on pistachio nuts. PCR (polymerase chain reaction) primers were designed by using DNA sequences derived from AFLAV. The primers were useful to profile individual A. flavus strain. More than fifty A. flavus strains isolated from different geological origins were surveyed. The fingerprint patterns (genotype) suggested that the region within the LTR retrotransposon is polymorphic among different strains of A. flavus.