Race structure characterization and genetic diversity analysis of Puccinia striiformis f. sp. tritici in Saskatchewan
G. S. Brar (1), G. S. BRAR (1), R. Kutcher (1), Y. B. Fu (2). (1) University of Saskatchewan, Saskatoon, SK, Canada; (2) Plant Gene Resources of Canada, Agriculture and Agri-Food Canada, Saskatoon Research Centre, Saskatoon, SK, Canada
Stripe rust of wheat, caused by <i>Puccinia striiformis</i> f. sp. <i>tritici (Pst) is one of the most devastating diseases of wheat world-wide. Selection pressure on the pathogen population may result in a rapid shift to races virulent on wheat genotypes with specific resistance genes. For successful disease management, it's important to monitor the virulence spectrum of the pathogen. The purpose of this research was to characterize the race structure of Pst in Saskatchewan and to determine genotypic diversity of the pathogen population. Race characterization was performed by inoculating 27 near-isogenic wheat lines, four supplemental lines and one triticale with 24 genetically uniform Pst isolates from Saskatchewan and other provinces of western Canada. Whole genome of the pathogen isolates was sequenced after DNA extraction, using the illumina MiSeq platform and polymorphisms were assessed by single nucleotide polymorphism (SNP) markers. Characterization of Pst isolates identified 18 races of the pathogen. Genes Yr1, Yr5, Yr15 and YrSP conditioned resistance against all races. Variation for virulence was observed among isolates on Yr10, Yr24 and YrSu. Genotypic diversity was not observed to be related to geographical location or virulence phenotypes of the isolates. The SNP data revealed little variation in the Pst population, suggesting clonal lineage, which means they were derived from one another by step-wise mutation.</i>
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