Leaf rust, caused by Puccininia triticina (Pt), is one of the most common wheat diseases in the Great Plains of the USA. A population of recombinant inbred lines (RILs) from CI 17884 x Bainong 418 was evaluated for responses to leaf rust race Pt52-2 and genotyped using single nucleotide polymorphism (SNP) markers. Quantitative trait locus (QTL) analysis identified a minor gene for resistance to leaf rust, designated QLr.stars-1RS, on the 1BL.1RS translocation segment in Bainong 418, and another leaf rust resistance gene, Lr47, on chromosome 7A of CI 17884. Lr47, originally identified in CI 17884 and located in a wheat-T. speltoides translocation segment 7S#1S, remains one of only a few race-specific resistance genes still effective in the Great Plains. A set of 7A-specific simple sequence repeat (SSR) markers were developed and used to genotype CI 17884 and a pair of near-isogenic lines differing in the presence or absence of 7S#1S, PI 603918 and Pavon F76. Haplotype analysis indicated that the estimated length of 7S#1S was 157.23 to 174.42 Mb, accounting for about 23% of the 7A chromosome. Two SNPs on 7S#1S and 4 SNPs on the 1RS chromosome arm were converted to KASP markers, which were subsequently validated in a panel of cultivars and recently released elite breeding lines. Of these, one and two KASP markers are specific to the 1RS chromosome arm and 7S#1S, respectively, indicating that they can facilitate the introgression of Lr47 and QLr.stars-1BS into locally adapted wheat cultivars and breeding lines.
Study of the leaf rust resistance gene Lr52 by targeted sequencing
