RANDOM AMPLIFIED POLYMORPHIC DNA MARKERS REVEAL A HIGH-DEGREE OF GENETIC DIVERSITY IN THE ENTOMOPATHOGENIC FUNGUS METARHIZIUM-ANISOPLIAE VAR ANISOPLIAE

Metarhizium anisopliae isolates from several insect hosts and from var ious sugar cane growing areas of Queensland, Australia, were examined for genetic diversity using random amplified polymorphic DNA (RAPD) ma rkers. Thirty isolates of M. anisopliae var. anisopliae and one isolat e of M. anisopliae var. majus were examined. Ten randomly chosen 10mer or 11mer primers were used and RAPD banding patterns were compared. T hirty distinct genotypes could be distinguished amongst the 31 isolate s tested on the basis of RAPD patterns. Six of the isolates classified as M. anisopliae var. anisopliae exhibited closer similarity to the M . anisopliae var. majus isolate than to other anisopliae strains teste d. Isolates exhibiting similar (>80% similarity) RAPD profiles tended to be isolated from the same geographic area and evidence for the pers istence of particular fungal genotypes in specific geographical locali ties was obtained. Pathogenicity assays suggested that, in some instan ces, RAPD groupings may also indicate insect host range. The mean simi larity amongst isolates measured by band sharing in all pairwise compa risons was 41% and the most distinct pair of isolates shared only 9% o f their RAPD bands. We conclude that the isolates tested belonging to the species M. anisopliae, as assessed on morphological grounds, repre sent a very diverse genetic group. The results also suggest that RAPD markers may be useful for the tracking of specific biocontrol strains in the field.