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Populations of Puccinia triticina, one of the casual agents of wheat leaf rust disease, in the pacific (British Columbia and Alberta), prairie (Manitoba and Saskatchewan), and eastern regions (Quebec and Ontario) of Canada from 1997 to 2007 were analyzed for virulence and genetic diversity by revealing expressed sequence tag derived simple sequence repeat (EST-SSR) polymorphisms. Since 1997, a significant shift in the virulence of P. triticina occurred across Canada. The diversity of P. triticina virulence phenotypes in Manitoba and Saskatchewan, as measured by Shannon and Simpson indexes, decreased due to the directional selection toward predominant virulence phenotypes, whereas it remained relatively constant in Quebec and Ontario. The clustering of P. triticina virulence phenotypes from 1997 to 2007 was similar to that found in previous years, and was correlated with virulence to leaf rust resistance genes Lr2a, Lr2c, and 1x17a. Distinct EST-SSR profiles were found in different groups of P. triticina virulence phenotypes based on virulence to Lr2a, Lrlc, and Lrl7a. In addition, the population of P. triticina in Manitoba and Saskatchewan was different from thai in Quebec and Ontario from 1997 to 2007, based on both virulence characteristics and EST-SSR genotypes. Key words: Puccinia triticina, wheat leaf rust, virulence, simple sequence repeat and diversity. Les auteurs ont analyse les populations du Puccinia triticina, l'agent causal de la rouille foliaire du ble dans les regions du pacifique (Colombie britannique et Alberta), des prairies (Manitoba et Saskatchewan) et de l'est (Quebec et Ontario) au Canada, de 1997 a 2007, en determinant la virulence et la diversite genetique mises en evidence par les polymorphismes par le polymorphisme de marqueurs de type microsatellites derive d'etiquettes de sequences exprimees (ESTSSR). Depuis 1997, on observe un glissement significatif de la virulence du P. triticina a travers le Canada. La diversite des phenotypes de virulence du P. triticina au Manitoba et en Saskatchewan, telle que mesuree par les index de Shannon el de Simpson, adiminue du a une selection directionnelle vers des phenotypes virulents predominants, alors que cette diversite est demeuree relativement constante au Quebec et en Ontario. Le regroupement des phenoiypes de virulence du P. triticina de 1997 a 2007, ne differe pas de celui observe au cours des annees antecedentes, et montre une correlation avec la virulence des genes de resistance a la rouille foliaire Lr2a, Lr2c et Lrl7a. On observe des profils EST-SSR dans differents groupes de phenotypes de virulence du P. triticina, bases sur les genes de virulence a Lr2a, Lrlc et Lrl7a. De plus, la population du P. triticina du Manitoba et de la Saskatchewan s'eloigne de celle du Quebec et de l'Ontario entre 1997 et 2007. en se basant a la fois sur les caracteristiques de virulence et sur les genotypes EST-SSR. Mots-cles : Puccinia triticina, rouille foliaire du ble, virulence, sequence a simple repetition et diversite. [Traduit par la Redaction], Introduction Wheat leaf rust, caused by Puccinia triticina Eriks, is a serious production problem in many wheat growing areas worldwide, including Canada (Kolmer 2005; McCallum and Seto-Goh 2009). Depending on [...]