Submitted to: Theoretical and Applied Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/6/2012
Publication Date: 10/23/2012
Citation: Xu, L.S., Wang, M., Chen, P., Kang, Z., Hulbert, S., Chen, X. 2012. Molecular mapping of Yr53, a new gene for stripe rust resistance in durum wheat accession PI 480148 and its transfer to common wheat. Theoretical and Applied Genetics. 126:523-533. Interpretive Summary: Stripe rust is one of the most damaging diseases of wheat worldwide. It is essential to identify new genes for effective resistance against the disease. Durum wheat PI 480148, originally from Ethiopia, was found by our program to have effective stripe rust resistance. To map the resistance gene and to transfer it to common wheat, a cross was made between PI 480148 and a susceptible common wheat genotype. Resistant F3 plants with 42 chromosomes were selected cytologically and by testing with stripe rust race PST-100. The segregation of 157 F4 plants from a single F3 plant with 42 chromosomes tested with PST-100 indicated a single dominant gene from PI 480148 conferring stripe rust resistance. Using the F4 population and molecular markers, the gene was mapped to the long arm of chromosome 2B. Closely linked molecular markers were identified for the resistance gene. The relationships of the resistance gene with those previously reported on the same chromosome were determined and the results identified the gene from PI 480148 as a new gene, and therefore perminantly designated as Yr53. Common wheat lines with Yr53 and combination of Yr53 and Yr5 (a effective stripe rust resistance gene also on the long arm of chromosomal 2B) were developed, which should be more useful for breeding programs to incorporate the gene and gene combination into commercial cultivars.
Technical Abstract: Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is one of the most damaging diseases of wheat worldwide. It is essential to identify new genes for effective resistance against the disease. Durum wheat PI 480148, originally from Ethiopia, was resistant in all seedling tests with several predominant Pst races in the US under controlled greenhouse conditions and at multiple locations subject to natural infection for several years. To map the resistance gene(s) and to transfer it to common wheat, a cross was made between PI 480148 and susceptible common wheat genotype Avocet S (AvS). Resistant F3 plants with 42 chromosomes were selected cytologically and by testing with Pst race PST-100. A total of 157 F4 plants from a single F3 plant with 2n = 42 tested with PST-100 segregated in a 3 resistant: 1 susceptible ratio, indicating that a single dominant gene from PI 480148 conferred resistance. Using the F3:4 population and the resistance gene-analog polymorphism (RGAP) and simple sequence repeat (SSR) markers, the gene was mapped to the long arm of chromosome 2B. SSR marker Xwmc441 and RGAP marker XLRRrev/NLRRrev350 flanked the resistance gene by 5.6 and 2.7 cM, respectively. The effective resistance of the gene to an Australian Pst isolate virulent to Yr5, which is also located on 2BL and confers resistance to all US Pst races, together with an allelism test of the two genes, indicated that the gene from PI 480148 is different from Yr5 and should be a new and useful gene for resistance to stripe rust. Resistant common wheat lines with plant types similar to AvS were selected for use in breeding programs.