Submitted to: Mycological Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 1997
Publication Date: N/A
Interpretive Summary: Paecilomyces fumosoroseus is a common soilborne fungus that infects many different species of insects worldwide. It is currently being developed as a biocontrol agent to integrate into pest management schemes for several pests. An obstacle to implementation of this approach is a thorough characterization of fungal strains prior to their release. In this study we used biochemical methods to generate two different types of genetic markers. With one marker we were able to determine which strains were compatible and capable of exchanging genetic information with one another. The other marker was used to generate DNA fingerprints of all the isolates. Both markers showed considerable genetic diversity among all 38 isolates studied. No correlation was observed between markers and either insect host or geographic origin. In addition, some compatible isolates were observed to be genetically unrelated. These markers could be useful in a program to determine the fate of organisms released in the environment.
Technical Abstract: Two classes of genetic markers, vegetative compatibility and random amplified polymorphic DNAs (RAPD), were evaluated for their ability to assess genetic variation among 38 isolates of the entomopathogenic fungus, Paecilomyces fumosoroseus. Both methods revealed significant polymorphisms. Nitrate non-utilizing mutants were generated from chlorate-containing media and used as forcing markers to observe heterokaryon formation and determine compatibility. Nineteen separate vegetative compatibility groups (VCG) were identified, only seven having at least two members. No correlation was observed between VCG and either insect host or geographic origin. Nine RAPD primers produced 365 unique fragments and could distinguish three different phenetic groups. RAPD profiles conclusively showed that strains within some VCGs were genetically yunrelated, indicating that these strains were not clonal in origin. The large number of VCGs suggests that formation of heterokaryons and possible genetic exchange are uncommon. DNA fingerprinting with RAPD-PCR provides high resolution of genotype distribution and could be useful in tracking the fate of biocontrol agents released into the environment.