DNA FINGERPRINTING OF THE PLANT PATHOGENIC FUNGUS MYCOSPHAERELLA-GRAMINICOLA (ANAMORPH-SEPTORIA-TRITICI)

DNA restriction fragment length polymorphisms (RFLPs) in the nuclear genome of the plant pathogenic fungusSeptoria tritici were used to discriminate among different clones in a population. A sample of 93 isolates collected from a single field was examined for genetic variation using two restriction enzymes and eight anonymous DNA probes which hybridized to single RFLP loci and one probe which hybridized to two RFLP loci. Twenty-two of the 559,872 possible multilocus haplotypes were identified among the isolates. Isolates with identical multilocus haplotypes were clustered in the field, suggesting that they originated by clonal reproduction. Probe pSTL40, which hybridized to sequences present on 3-5 different chromosomes, differentiated 21 DNA fingerprint patterns among the 93 isolates. With three exceptions, isolates with identical multilocus haplotypes had identical DNA restriction fragment profiles when hybridized with pSTL40. The probe pSTL29, which hybridized to sequences present on 7-10 different chromosomes, identified 21 different DNA fingerprint patterns among the 22 multilocus haplotypes. Pairwise comparisons of genetic similarity among clones were calculated using proportion of shared alleles at individual RFLP loci and proportion of shared restriction fragments in DNA fingerprints. The two measures of genetic similarity were not correlated for any of the three DNA fingerprinting combinations tested, suggesting that DNA fingerprints may not provide an accurate measure of genetic similarity among clones in fungal populations. © 1991 Academic Press, Inc.