Twenty-one isolates of the nematode-vectored plant
pathogen, Dilophospora alopecuri, were examined by
allozyme electrophoresis.
The study focused on isolates from Australia, including
those associated with populations of the seed-gall nematode,
Anguina funesta, in Western Australia (W.A.), where
the fungus apparently provides natural control of the
A. funesta–Clavibacter toxicus association
responsible for annual ryegrass toxicity, and a range of
Anguina populations in south-eastern Australia.
Reference strains from international culture collections
were included. Variation was found in 26 of 27 presumptive
loci and 10 electrophoretic types were
identified. All Australian isolates fell into six electrophoretic
types that formed two groups of three that differed by less
than 13% within each group, but differed by over 70% between
the groups. Of the isolates from W.A., six fell into one
electrophoretic type and one into a second electrophoretic type
that differed at one locus only. Three exotic isolates varied
from Australian ones by
27–74%. Dilophospora alopecuri exhibited
greater within-species allelic variation than previously
reported for asexually-reproducing
halophase fungi. The lack of variation within W.A. suggests
that (i) a teleomorph does not occur under local conditions,
(ii) the W.A. population has arisen from a single introduction
and (iii) selection of strains suitable for biocontrol of
Anguina funesta and Clavibacter
toxicus should include material from eastern Australia.