|St Amand, Paul|
|CARVER, BRETT - OKLAHOMA STATE UNIVERSITY|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/6/2019
Publication Date: N/A
Technical Abstract: Leaf rust, caused by Puccinia triticina Erikss. (Pt), is the most common disease of wheat (Triticum aestivum L.) worldwide. Most leaf rust resistance genes have lost effectiveness in the Great Plains of the USA because of the abundant variation in Pt populations. Identification of novel leaf rust resistance genes is imperative for sustainable wheat production. To characterize the leaf rust resistance gene in Iranian landrace PI 622111, an F2 population and 175 F2:3 lines derived from PI 622111 × Yuyuan 3 were evaluated for seedling responses to Pt race Pt52-2 (MMPSD). The '2 tests indicated a single gene segregated in the F2 and F3 populations ('2 3:1 = 1.15, df = 1, p = 0.28; '2 1:2:1 = 2.39, df = 2, p = 0.30). Based on F2:3 phenotypic data, 12 F2 plants showing homozygous resistance and 12 F2 plants exhibiting homozygous susceptibility were sequenced to develop GBS (genotyping by sequencing) markers, leading to the identification of S5B_9219863, positioned at 9,219,863 bp on the short arm of chromosome 5B in the Chinese Spring IWGSC RefSeq v.1.0 reference sequence. All resistant and susceptible plants carried ‘A’ and ‘G’ alleles at the S5B_9219863 locus, respectively, indicating that the leaf rust resistance gene in PI 622111 is close to S5B_9219863. A total of 1,445 SSR loci were identified in the terminal region (0-13.5 Mb) of chromosome 5BS, and 48 of them were chosen to develop SSR markers. Linkage analysis delimited the leaf rust resistance gene in PI 622111, designated Lr622111, in an interval of 1.1 Mb flanked by Xstars669 (6.5 Mb) and Xstars678 (7.6 Mb). Lr622111 was 0.5 cM proximal to Xstars669 and 6.1 cM distal to Xstars678. Lr622111 is a new gene differing with Lr52, a leaf rust resistance gene located on 5BS, in responses to Pt races. Lr622111 can be used to enhance leaf rust resistance in the Great Plains of the USA.