Evidence for the Lr46 leaf rust resistance gene in the wheat cultivar Carberry

Stacking and deployment of pleiotropic genes for resistance to multiple fungal diseases in wheat variety development is expected to increase the durability of resistance. To achieve this gene stacking objective through molecular breeding, an understanding of which genes currently exist in adapted germplasm is necessary. The cultivar Carberry is a popular hard red spring wheat variety in Canada with good rust resistance. Pedigree, phenotype, and DNA marker evidence suggested Carberry possesses the leaf rust resistance gene Lr46. Lr46 is a slow rusting adult plant resistance gene located on chromosome 1B that provides resistance against leaf rust and other diseases such as stripe rust, stem rust, and powdery mildew. We undertook an investigation to test the hypothesis that Carberry possesses Lr46. A doubled haploid population comprising 297 lines was developed from the F1 of a cross of Carberry with the universally leaf rust susceptible cultivar Thatcher. The population was evaluated for leaf rust reaction in four field nursery environments: near Swift Current SK from 2014 to 2016, and Morden MB in 2016. The population was also assessed for stem rust response in 2014 and 2016 near Swift Current. The population was genotyped using the 90K Infinium iSelect assay and following linkage map construction with JoinMap 4.1, 5457 markers were used for quantitative trait locus (QTL) analysis using MapQTL 6. Two QTL for leaf rust resistance were identified from Carberry on chromosome 1B, one of which was coincident with a stem rust resistance QTL that mapped to the location of Lr46.