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Title: Yr45, A new wheat gene for stripe rust resistance mapped on the long arm of chromosome 3D

Author
item LI, QIANG - Washington State University
item Chen, Xianming
item WANG, MEINAN - Washington State University
item JING, JINXUE - Northwest Agriculture And Forestry University

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/25/2010
Publication Date: 9/14/2010
Citation: Li, Q., Chen, X., Wang, M., Jing, J. 2010. Yr45, A new wheat gene for stripe rust resistance mapped on the long arm of chromosome 3D. Theoretical and Applied Genetics. 122:189-197.

Interpretive Summary: Stripe rust is one of the most destructive diseases of wheat worldwide. Growing resistant cultivars is the most effective approach to control the disease, but only few genes are available conferring effective all-stage resistance against the current populations of the pathogen worldwide. It is urgent to identify new genes for diversifying resistance genes and pyramiding genes for different types of resistance in order to achieve high-level and durable resistance for sustainable control of stripe rust. The common spring wheat germplasm ‘PI 181434’, originally from Afghanistan, was resistant in all greenhouse and field tests. In this study, we identified a dominant resistance gene in PI 181434 and mapped it to the long arm of wheat chromosome 3D. Because it is the first stripe rust resistance gene identified on 3D, the gene is different from all previously reported genes for resistance to the disease and is officially named Yr45. We tested two closely linked resistance gene analog polymorphism (RGAP) markers in 45 wheat cultivars and found that they were polymorphic in 73.3% and 82.2% of the cultivars. Therefore, the markers can be directly used to incorporate the gene into most wheat cultivars. For the cultivars that did not show size polymorphism, we sequenced the marker fragments and identified single nucleotide polymorphisms (SNPs) that separated these cultivars from PI 181434. Thus, the RGAP markers and SNP markers can be used in marker-assisted selection to incorporate the new gene basically into any wheat cultivars.

Technical Abstract: Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the most destructive diseases of wheat worldwide. Growing resistant cultivars is the most effective approach to control the disease, but only few genes are available conferring effective all-stage resistance against the current populations of the pathogen worldwide. It is urgent to identify new genes for diversifying resistance genes and pyramiding genes for different types of resistance in order to achieve high-level and durable resistance for sustainable control of stripe rust. The common spring wheat genotype ‘PI 181434’, originally from Afghanistan, was resistant in all greenhouse and field tests in our previous studies. To identify the resistance gene(s) in the genotype, PI 181434 was crossed with susceptible genotype ‘Avocet Susceptible’. Adult plants of 103 F2 progeny were tested in the field under the natural infection of P. striiformis f. sp. tritici. Seedlings of the parents, F2 and F3 were tested with races PST-100 and PST-127 of the pathogen under controlled greenhouse conditions. The genetic study showed that PI 181434 has a single dominant gene conferring all-stage resistance. The resistance gene analog polymorphism (RGAP) and simple sequence repeat (SSR) techniques were used to identify molecular markers linked to the gene. A linkage map of 8 RGAP markers and 2 SSR markers was constructed for the gene using the 103 F2 plants with their derived F3 lines tested in the greenhouse. Amplification of the complete set of nulli-tetrasomic lines and selected ditelosomic lines of Chinese Spring with an RGAP marker and the two SSR markers mapped the gene on the long arm of chromosome 3D. Because it is the first gene for stripe rust resistance mapped on 3DL and different from all previously named Yr genes, the gene in PI 181434 was designated as Yr45. Polymorphism rates of the two closest flanking markers, Xwgp115 and Xwgp118, in 45 wheat genotypes were 73.3% and 82.2%, respectively. Single nucleotide polymorphisms (SNPs) were identified in the eight wheat genotypes sharing both flanking markers. The RGAP markers and potential SNP markers should be useful in incorporating the gene into wheat cultivars and pyramiding with other genes for durable resistance.