DIVERSITY AND MULTILOCUS GENETIC-STRUCTURE IN POPULATIONS OF CRYPHONECTRIA-PARASITICA

Genetic diversity and multilocus genetic structures of four population s of the chestnut blight fungus, Cryphonectria parasitica, were analyz ed. Two populations in Michigan had very low vegetative compatibility (vc) type diversity and also low diversity of DNA fingerprints and mit ochondrial DNA (mtDNA) haplotypes. A population in Teano, in southern Italy, had low ve type diversity but higher levels of fingerprint anti mtDNA haplotype diversity. In contrast, a population in Finzel, Maryl and, had high diversity for all markers. Mating type was in a 1:1 rati o in one Michigan population and in Finzel but significantly deviated from 1:1 in the other populations. DNA fingerprints were more similar within ve types than between ve types in Teano but nor in Finzel; lack of diversity for all markers precluded similar analyses for the Michi gan populations. Based on tests for gametic disequilibrium and genotyp ic diversity, the multilocus structure in Finzel was consistent with a hypothesis of random mating. In contrast, the random mating hypothesi s was rejected in Teano for the full sample but not within the dominan t ve type, which comprised 75% of the sample. Recombinant va types bet ween the two common ve types in Teano were found only rarely in the fi eld, and DNA fingerprints did not always correlate to mtDNA haplotypes and ve types, indicating that recombination occurs infrequently in Te ano. These results demonstrate that ve diversity does not necessarily correlate to diversity of other genetic markers but may be related to the reproductive biology of C. parasitica in nature.