Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2003
Publication Date: 11/30/2004
Citation: Chen, X., Soria, M.A., Yan, G.P., Sun, J., Dubcovsky, J. 2004. Development of sequence tagged site and cleaved amplified polymorphic sequence markers for wheat stripe rust resistance gene yr5. Crop Science. 43:2058-2064. Interpretive Summary: Stripe rust is one of the most destructive diseases of wheat in the western United States and has become increasingly important in the central United States. Growing resistant cultivars is the most effective, economical, and environmentally friendly method to control the disease. Molecular markers are useful for more efficiently incorporating resistance genes into commercial varieties. The wheat gene Yr5 is effective against all strains of the stripe rust pathogen in the United States. We previously identified markers completely associated with the resistance gene. However, those markers were difficult to use. In this study, we developed more user-friendly markers from the previous markers and tested the usefulness of the markers with a set of diverse wheat varieties. The new markers were not only easier to use, but also worked well in backgrounds of the most wheat varieties that were tested. These markers should be more useful to accelerate incorporation of the resistance gene into wide range of wheat varieties and also to combine this gene with other genes for durable and superior resistance.
Technical Abstract: The Yr5 gene confers resistance to all races of the wheat stripe rust pathogen (Puccinia striiformis f. sp. tritici) in the United States. Co-segregating resistance gene analog polymorphism (RGAP) markers for Yr5 are available but their use is cumbersome. To develop user-friendly markers for Yr5, sequence tagged site (STS) primers were designed based upon the sequences of RGAP markers Xwgp-18 (AY167598) from cultivar 'Avocet Susceptible' (AVS) and Xwgp-17 (AY167597) from the Yr5 near isogenic line (Yr5) of AVS carrying the Yr5 gene from 'Triticum spelta album' (TSA). Three sets of STS markers (2 co-dominant and one dominant) were developed to amplify a region including a polymorphic 6-bp indel (insertion/deletion). The co-segregation of the STS markers with Yr5 was confirmed with 114 BC7:F3 lines developed from the cross between AVS and TSA. However, the indel was not polymorphic in some cultivars and advanced breeding lines that did not have the Yr5 gene, precluding the use of the STS markers in crosses using these backgrounds. Fortunately, most of the susceptible lines including those that were not polymorphic for the 6-bp indel showed an additional single base pair polymorphism. These susceptible lines have an additional Dpn II restriction site that is absent in the lines carrying Yr5. The cleaved amplified polymorphic sequence (CAPS) markers based on the Dpn II polymorphism was useful to differentiate most of the elite breeding lines and cultivars from the Yr5 allele. The co-dominant STS and CAPS markers presented in this study are easier to use than the original RGAP markers, and would be valuable tools to accelerate the introgression of Yr5 into commercial cultivars.