Genetic mapping and marker development for the leaf rust resistance gene Lr30 in wheat (Triticum aestivum L.)

Canadian spring wheat cultivars AAC Concord and Lillian possess Lr30, a gene that confers resistance against leaf rust caused by Puccinia triticina Eriks. (Pt). The objectives of this study were to generate the first linkage map of Lr30, and develop Kompetitive allele-specific PCR (KASP) markers linked to Lr30 for marker-assisted breeding. Two doubled haploid (DH) populations were generated from the crosses Lillian × Glenlea (LG) and CDC Hughes × AAC Concord (HC). The LG population was phenotyped for seedling leaf rust reaction using the Lr30 avirulent Pt isolates 96–12-3 MBDS, 74–2 MGBJ, 06–1-1 TDBG, and 77–2 TJBJ, and both populations were phenotyped with Pt isolate 21–21-1 TNBJ. The 90k iSelect SNP array was used to genotype the populations for linkage mapping. The LG population showed a 1:1 resistant to susceptible monogenic segregation ratio for all five Pt isolates, where the resistance to each race co-segregated. The HC population also showed a 1:1 phenotypic ratio when inoculated with Pt isolate 21–21-1 TNBJ. Lr30 was localized to genetic intervals of 2.7 cM and 1.6 cM on chromosome 4A of the LG and HC linkage maps, respectively. The physical location of Lr30 in the Chinese Spring wheat RefSeq.V.2.1 spans approximately between positions 522.0 Mb and 548.0 Mb of chromosome 4A. KASP markers were designed and validated for functionality using the LG and HC populations, backcross lines of wheat cultivar Pasqua with Thatcher, and a panel of 193 wheat cultivars. These new KASP markers are well-suited to marker-assisted breeding.