Identification of the crayfish plague fungus Aphanomyces astaci by polymerase chain reaction and restriction enzyme analysis.

To characterise the DNA of the crayfish plague fungus Aphanomyces astaci, Saprolegniales (Oomycetes), primers were developed to amplify a 1050bp segment of the 28S rDNA region. Restriction enzymes were applied to the amplicon obtained, to distinguish A. astaci from 12 fungal species belonging also to the Saprolegniales and five more distantly related fungi. Most of the fungal species included in the study are either known parasites of freshwater crayfish cuticle or can be found in their natural environment. A. astaci DNA was distinguishable from the DNA of other fungal species tested by using the primers developed plus restriction enzymes AluI, HindIII and AvaI. Prior to this study, methods for A. astaci-species determination, e.g. spore production and infection experiments, required a protracted period to yield results; the method described in this study is quicker.