GEOGRAPHIC-VARIATION OF CHONDROSTEREUM-PURPUREUM DETECTED BY POLYMORPHISMS IN THE RIBOSOMAL DNA

Variation in the ribosomal (rDNA) repeat was analyzed for 107 isolates of the pathogenic fungus Chondrostereum purpureum, collected from Eur ope, New Zealand, and North America. The rDNA repeat of a representati ve Canadian isolate of C. purpureum was cloned into the lambda vector EMBL-3, and a detailed restriction map was constructed. Variation in t he large non-transcribed spacer region of the rDNA was determined for the entire collection of isolates following amplification by the polym erase chain reaction (PCR) and analysis of restriction fragment length polymorphisms (RFLPs). Three distinct nuclear type patterns were iden tified using the restriction endonuclease HaeIII. Nuclear type I was f ound in North American, European, and New Zealand isolates. Nuclear ty pe II was only detected in isolates collected from North America, and nuclear type III was observed in isolates collected from both Europe a nd New Zealand. Nuclear type I was the predominant nuclear type in eas tern North America as indicated by a frequency of 0.78, and nuclear ty pe II occurred with a frequency of 0.89 in western North America. Gene flow across the continent was indicated by nearly equal nuclear type distributions (nuclear type I, 0.41; nuclear type II, 0.59) in central North America, but geographic separation has led to unequal nuclear-t ype distributions across North America.