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The Frequencies and Spatial Distribution of Mating Types in Stagonospora nodorum Are Consistent with Recurring Sexual Reproduction

March 2006 , Volume 96 , Number  3
Pages  234 - 239

Rubik J. Sommerhalder , Bruce A. McDonald , and Jiasui Zhan

First and second authors: Institute of Integrative Biology, Plant Pathology, ETH Zurich, LFW, CH-8092 Zürich, Switzerland; First and second authors: Scottish Crop Research Institute Invergowrie, Dundee DD2 5DA, Scotland, UK

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Accepted for publication 26 September 2005.

To test the hypothesis that Stagonospora nodorum undergoes regular cycles of sexual recombination, a total of 1,207 isolates sampled from 18 fields in 12 geographical regions in six countries on five continents were analyzed for mating type frequency and distribution using polymerase chain reaction amplification of the mating type locus. Restriction fragment length polymorphism and random amplified polymorphic DNA fingerprints were used to clone-correct the data sets. Both mating types were often found on the smallest spatial scales tested, including within the same lesion, the same leaf, and the same 1-m2 plot. In only one case out of the 18 fields tested was there a significant departure from the expected 1:1 ratio. Combining this result with previous data on the population structure of S. nodorum, we conclude that this pathogen undergoes regular cycles of sexual recombination in all regions we examined.

Additional keywords: epidemiology, hierarchical sampling, Phaeosphaeria nodorum, population genetic structure.

© 2006 The American Phytopathological Society