Genetic mapping of leaf rust resistance in the tetraploid wheat cross Strongfield/Blackbird

Leaf rust, caused by Puccinia triticina Eriks. (Pt), is an economically important disease of wheat worldwide. Deploying wheat cultivars with effective leaf rust resistance (Lr) genes is an efficient method for disease management. The genetic basis of leaf rust resistance was studied a doubled haploid (DH) population of the cross Strongfield/Blackbird. Strongfield is a widely grown durum wheat variety (Tritucum Triticum turgidum var. durum L.; genome AABB) in Canada, which was developed at Agriculture and Agri-Food Canada, Swift Current. Strongfield is highly resistant to Pt in Canada. Blackbird (Tritucum Triticum carthlicum; genome AABB) is susceptible to Pt at the seedling stage but may possess possesses partial adult plant resistance to leaf rust. The genetic basis of leaf rust resistance was studied in a doubled haploid (DH) population of the cross Strongfield/Blackbird which was previously genotyped with SSR markers and the 90K wheat Infinium SNP array. Total Fof four valuable QTLs were found on chromosomes 1B, 2B, 3A, and 3B based the analysis of leaf rust reaction from an inoculated field nursery nurseries in 2016 and 2017; one was found on chromosome 3AS in Strongfield and three QTLs were found on chromosome 1B, 2B and 3B separately. This population was then screened for leaf rust resistance with multiple races at the seedling stage indoors; Blackbird was susceptible while Strongfield was resistant. One leaf rust resistance Lr gene was identified on chromosome 3AL, mapping to the same location as the 3A QTL detected with the field leaf rust data based upon seedling inoculation data and 90K wheat Infinium SNP genotype results.