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Title: Linkage maps of wheat stripe rust resistance genes Yr5 and Yr15 for use in marker assisted selection

Author
item Murphy, Lesley
item SANTRA, D - WASHINGTON STATE UNIV
item KIDWELL, K - WASHINGTON STATE UNIV
item YAN, G - OREGON STATE UNIV
item Chen, Xianming
item Garland-Campbell, Kimberly

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/21/2008
Publication Date: 9/1/2009
Citation: Murphy, L.R., Santra, D., Kidwell, K.K., Yan, G.P., Chen, X., Garland Campbell, K.A. 2009. Linkage maps of wheat stripe rust resistance genes Yr5 and Yr15 for use in marker assisted selection. Crop Sci. 49:1-5.

Interpretive Summary: Wheat stripe rust (also known as yellow rust) is a serious global disease of wheat. Two important stripe rust resistance genes, Yr5 and Yr15, are being bred into wheat and are the only known all-stage resistance genes that provide protection from all stripe rust races currently found in the United States. To determine whether wheat lines have these important genes, it is easiest to use genetic tools; however, previously published markers for these genes are not very effective. Our objective was to create new maps for both genes using a combination of markers and to evaluate their effectiveness across a variety of wheat lines. Two populations were created using Avocet-Susceptible as a susceptible parent and Triticum aestivum ssp. spelta ‘Album’ and Triticum dicoccoides ‘V763-251’ as the Yr5 and Yr15 donors, respectively, and were evaluated for resistance to multiple races of stripe rust. Molecular markers that had been previously mapped to wheat chromosome 1B (Yr5) or 2B (Yr15) were mapped to the appropriate population. Linkage maps were constructed using JoinMap and the markers closest to each gene were then tested on the various wheat lines. None of the markers that mapped closely to the Yr5 gene were diagnostic in all genetic backgrounds, although there are combinations that would be effective in gene identification. However, Xbarc8 and Xgwm413 appear to be completely linked with the gene in our Yr15 population and were diagnostic in almost all backgrounds tested. We have identified several useful SSR and STS markers for introgression of Yr5 and Yr15 and developed maps for both genes comprised of several marker types.

Technical Abstract: Wheat stripe rust (also known as yellow rust) caused by Puccinia striiformis Westend. f. sp. tritici Eriks. is a serious global disease of wheat. Two important stripe rust resistance genes, Yr5 and Yr15, are being introgressed into wheat in several breeding programs and are the only known all-stage resistance genes that defeat all stripe rust races currently found in the United States. Previously mapped and published markers for these genes, however, show limited polymorphism across diverse genotypes and/or map at a fairly large distance from the genes, reducing the effectiveness of marker assisted selection for these genes, individually and in combination. Our objective was to create new linkage maps for both genes using a combination of available STS and SSR loci and to evaluate closely linked markers across a diverse panel of wheat genotypes. Two recombinant inbred populations created using Avocet-Susceptible as a susceptible parent and Triticum aestivum ssp. spelta ‘Album’ and Triticum dicoccoides ‘V763-251’ as the Yr5 and Yr15 donors, respectively, were evaluated for resistance to multiple races of stripe rust. Molecular markers that had been previously mapped to wheat chromosome 1B (Yr5) or 2B (Yr15) were mapped to the appropriate population. Linkage maps were constructed using JoinMap. Markers most closely linked to each gene were evaluated against a panel of genotypes collected from active introgression programs in the US. The STS7/8 marker mapped closest to Yr5 flanked by Xbarc349 and Xbarc167, although none of these markers were diagnostic in all genetic backgrounds. For Yr15, Xbarc8 and Xgwm413 appear to be completely linked with the gene in our population, along with RGAP marker Xwgp99. We have identified several useful SSR and STS markers for introgression of Yr5 and Yr15 and have developed linkage maps for both genes comprised of several marker types.