Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2012
Publication Date: 5/15/2012
Citation: Rouse, M.N., Nava, I., Chao, S., Jin, Y., Anderson, J. 2012. Identification of markers linked to the Ug99 stem rust resistance gene Sr28 in wheat (Triticum aestivum L.). Theoretical and Applied Genetics. Available: http://www.ncbi.nlm.nih.gov/pubmed/22584633. Interpretive Summary: Wheat stem rust disease has caused devastating yield losses in wheat in the United States and worldwide. Over the last several decades, stem rust has been controlled worldwide through the use of wheat genetic resistance. A stem rust race known as Ug99, first detected in Uganda in 1998, threatens United States and global wheat production because of its ability to infect nearly all currently grown wheat varieties. Sources of resistance need to be identified and characterized to facilitate their use in agriculture. A wheat line from South Dakota State University developed in the 1940's, line SD 1691, displayed resistance to Ug99 in field screening in Kenya. We identified a single resistance gene present in SD 1691 accounting for this resistance. We provided evidence that this stem rust resistance gene is the same as a previously known gene called 'Sr28'. We identified molecular markers linked to 'Sr28' and validated the usefulness of these markers for application in the central United States spring wheat production area. Identification of these markers will allow for wheat breeders to select for resistance to Ug99 faster and at lower cost. The findings of this research will benefit wheat farmers and distributors by providing wheat breeders with the necessary tools to rapidly and efficiently protect wheat yields with genetic resistance to Ug99.
Technical Abstract: Wheat stem rust caused by Puccinia graminis f. sp. tritici can cause devastating yield losses in wheat. Over the last several decades, stem rust has been controlled worldwide through the use of genetic resistance. Stem rust race TTKSK (Ug99), first detected in Uganda in 1998, threatens global wheat production because of its unique virulence combination. As the majority of the currently grown cultivars and advanced breeding lines are susceptible to race TTKSK, sources of resistance need to be identified and characterized to facilitate their use in agriculture. Year 1947 South Dakota breeding line SD 1691 displayed resistance to race TTKSK in the international wheat stem rust nursery in Njoro, Kenya. Seedling screening of progeny derived from SD 1691 crossed to susceptible LMPG-6 indicated that a single resistance gene was present. Allelism and race-specificity tests indicated the stem rust resistance gene in SD 1691 is Sr28. The chromosome arm location of Sr28 was previously demonstrated to be 2BL. We identified molecular markers linked to Sr28 and validated this linkage in two additional populations. Common spring wheat cultivars in the central United States displayed allelic diversity for markers flanking Sr28. These markers could be used to select for Sr28 in breeding populations and for combining Sr28 with other stem rust resistance genes.