Submitted to: Canadian Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2005
Publication Date: 12/1/2005
Citation: Mcalpin, C.E., Wicklow, D.T. 2005. DNA fingerprinting analysis of Petromyces alliaceus (Aspergillus section Flavi). Canadian Journal of Microbiology. 51(12):1039-1044. Interpretive Summary: The fungus Petromyces alliaceus is considered responsible for an important nephrotoxic mycotoxin that is occasionally observed in California fig orchards. The management of mycotoxin contamination in fig orchards requires that we identify potential sources of P. alliaceus contamination (i.e. soil, maize insects, air-spora, etc.) and determine which of these populations actually contaminate the figs with mycotoxins. To accomplish this objective a DNA probe was tested and produced DNA fingerprints that distinguished among genetically distinct isolates of P. alliaceus. This research is important to the dried fruit industry because the DNA probe offers a tool for monitoring specific P. alliaceus populations and for estimating the diversity of P. alliaceus in orchards, vineyards or crop fields.
Technical Abstract: The objective of this study was to evaluate the Aspergillus flavus pAF28 DNA probe's ability to produce DNA fingerprints for distinguishing among genotypes of Petromyces alliaceus section Flavi, a fungus considered responsible for the ochratoxin A contamination that is occasionally observed in California fig orchards. Petromyces alliaceus (14 isolates), Petromyces albertensis (1 isolate) and seven species of Aspergillus section Circumdati (14 isolates) were analyzed by DNA fingerprinting using a repetitive sequence DNA probe pAF28 derived from A. flavus. The presence of hybridization bands with the DNA probe and the P. alliaceus or P. albertensis genomic DNA indicates a close relationship between A. flavus and Petromyces alliaceus section Flavi. Twelve distinct DNA fingerprint groups or genotypes were identified among the 15 isolates of Petromyces. Species belonging to Aspergillus section Circumdati hybridized only slightly at the 7.0 kb region with the repetitive DNA probe, unlike the highly polymorphic hybridization patterns obtained from P. alliaceus and A. flavus, suggesting very little homology of the probe to Aspergillus section Circumdati genomic DNA. The pAF28 DNA probe offers a tool for typing and monitoring specific P. alliaceus clonal populations and for estimating the genotypic diversity of P. alliaceus in orchards, vineyards or crop fields.