Resumo

RODRIGUEZ-GARCIA, M. Florencia et al. Analysis of wheat (Triticum aestivum L.) yellow rust (Puccinia striiformis f. sp. tritici) virulence in the High Valleys of Mexico. Agrociencia [online]. 2010, vol.44, n.4, pp.491-502. ISSN 2521-9766.

Wheat yellow rust (Puccinia striiformis f. sp. tritici) causes major losses in wheat (Triticum aestivum L.) yields in the High Valleys of México because the fungus can evolve and overcome the resistance bred into new varieties. Therefore, the virulence of this pathogen was studied in the High Valleys of México during the spring-summer crop cycles of 2005, 2006, and 2007. Leaves and spikes infected by the fungus causing wheat yellow rust were collected in the production zones of the states of Tlaxcala, Hidalgo, Puebla, and the Estado de México. Samples were processed in the Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT), located in El Batán, Texcoco, Estado de México. To identify the physiological races, 14 isogenic lines and 10 varieties were used. The results indicated the presence of 39 races; the most frequent was 219MEX0, (15.6%) previously identified in 2003, which overcame the resistance of Yr1 gene. Following in frequency were 218MEX0 (6.4%) and 91MEX0 (8.2%). Races 122MEX0, 377MEX0, 378MEX0, 506MEX0, and 507MEX0 were present in the 2005 and 2006 spring-summer cycle, while races 218MEX0, 219MEX0, and 251MEX0 were present in the 2006 and 2007 spring-summer cycles. It was determined that in the High Valleys of México there is virulence for the genes Yr1, 2, 3, 6, 7, 8, 9, 17, 27, Poll and YrA and avirulence for Yr5, 10, 15, 24, 26, and YrSp. The identified races were also characterized in the set of European and world differential genotypes, where the following equivalences were found: 730MEX0=70E0, 122MEX0=38E148, 219MEX0=135E6, 472MEX0=134E132, 346MEX0=134E2, 250MEX0=134E22, 216MEX==134E134, 251MEX0= 135E150, 89MEX0=199E0, 248MEX0=6E18, 88MEX0= 6E2, 218MEX0=6E6, and 478MEX0=70E0. When the differential lines of the world set were used, it was found that the equivalence 134 with virulence for the Yr7, 6, 9+ genes has been recorded in Ethiopia, Kenya, Syria and Yemen since 1992. The identification of physiological races and knowledge of the virulence of the pathogen is important as a useful tool in breeding and releasing new varieties with genetic combinations that are more effective in the control of yellow rust.

Palavras-chave : P. striiformis f. sp. tritici, genes; varieties; physiological race; wheat; Yr.

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