Two types of genetic markers, vegetative compatibility
and RAPD, were evaluated for their ability to assess genetic
variation among 38 isolates of the entomopathogenic fungus,
Paecilomyces fumosoroseus. Both markers revealed
significant polymorphisms.
Nitrate non-utilizing mutants were generated from
chlorate-containing media and used as forcing markers to
observe heterokaryon
formation and determine vegetative compatibility. Nineteen
separate vegetative compatibility groups (VCGs) were
identified, only
seven having at least two members and 12 represented by
single isolates. 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 unrelated, 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.