A genome-wide association study of resistance to the yellow rust pathogen (Puccinia striiformis f. sp. tritici) in elite UK wheat germplasm

ABSTRACT Pauline G. M. Bansept-Basler, 2013 A genome wide association study of resistance to the yellow rust pathogen (Puccinia striiformis f. sp. tritici) in elite UK wheat germplasm Identification of marker-trait associations (MTA) in germplasm relevant to breeding program via association mapping (AM) can be an effective way to identify loci useful for selection. This approach does not require the generation of specific mapping populations and takes advantage of historical phenotypic data. In the present study, an association panel of 327 bread wheat varieties have been assembled and genotyped with 1806 DArT markers. Genetic structure analysis revealed a low stratification of the panel based on geographical origin (UK versus mixed European varieties) and a close relatedness between lines, which is confirmed by pedigree information. Historical evaluations against the yellow rust pathogen (Puccinia striiformis f.sp. tritici (Pst)) carried in the United Kingdom between 1990 and 2009, as well as de novo evaluations against recent Pst races have been collected and analysed for MTAs. Association scans considering historical data focused on specific Pst pathotypes and de novo seedling tests identified markers linked to known racespecific Yr genes Yr6, Yr7, Yr9, Yr17 and Yr32. When evaluated against current Pst races in the field, 35% of the lines from the panel presented repeatedly a high level of resistance (Area Under the Disease Progress Curve relative