Molecular polymorphism and virulence phenotypes of the wheat leaf rust fungus Puccinia triticina in Canada

Sixty-nine Puccinia triticina isolates from the eastern region of Ontario and Quebec, the prairie region of Manitoba and Saskatchewan, and Alberta were tested for virulence to 22 near-isogenic Thatcher wheat lines in seedling tests and the Thatcher line with Lr22b in adult plant tests. The isolates were also tested for amplified fragment length polymorphism (AFLP) using 10 specific amplification primer pairs. Thirty-seven distinct virulence phenotypes were identified using the Thatcher lines and 69 molecular phenotypes were identified with 164 AFLP markers. The correlation of isolate grouping based on virulence phenotypes and AFLP phenotypes was 0.53. Almost all isolates from Manitoba and Saskatchewan with virulence to Lr17 had AFLP phenotypes that differed significantly from isolates in the same region that were avirulent to Lr17. This indicated that isolates with virulence to Lr17 are most likely a recent introduction to the prairie region. The presence of distinct groups of isolates based on virulence and AFLP variation provides evidence that a number of different P. triticina phenotypes have been introduced to North America.Key words: Puccinia recondita f.sp. tritici, AFLP, specific virulence.