|ZURN, JASON - North Dakota State University|
|Rouse, Matthew - Matt|
|SHIAOMAN, CHAO - North Dakota State University|
|STHAPIT, JINITA - Washington State University|
|WANYERA, RUTH - Kenya Agricultural Research Institute|
|NJAU, PETER - Kenya Agricultural Research Institute|
|BRUEGGEMAN, ROBERT - North Dakota State University|
|ACEVEDO, MARICELIS - North Dakota State University|
Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2014
Publication Date: 4/3/2014
Citation: Zurn, J.D., Newcomb, M.S., Rouse, M.N., Jin, Y., Shiaoman, C., Sthapit, J., See, D.R., Wanyera, R., Njau, P., Bonman, J.M., Brueggeman, R., Acevedo, M. 2014. High density mapping of a resistance gene to Ug99 from an Iranian landrace. Molecular Breeding. 34:871-881.
Interpretive Summary: Managing the disease wheat stem rust is imperative for the preservation of global food security. A new race called TTKSK is speading throughout Africa and the Middle East and is particularly dangerous. The most effective strategy for managing this devastating disease is pyramiding several resistance genes into adapted wheat cultivars. A search for new sources of TTKSK resistance identified the spring wheat landrace PI 626573 as a new source of resistance. We identified that this wheat landrace possesses a resistance gene effective to TTKSK stem rust. The gene, named SrWLR, was identified on chromosome arm 2BL in wheat. We also identified molecular markers linked to SrWLR. The molecular markers linked to this gene may be useful for efficient breeding of resistant resistant wheat cultivars to protect United States wheat production from the threat of TTKSK wheat stem rust.
Technical Abstract: Managing the disease wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt) including the highly virulent race TTKSK is imperative for the preservation of global food security. The most effective strategy for managing this potentially devastating disease is pyramiding several resistance genes into adapted wheat cultivars. A search for new sources of Pgt race TTKSK resistance identified the spring wheat landrace accession PI 626573 as a potentially novel source of resistance. A recombinant inbred population was developed with the susceptible line LMPG-6 to characterize and map the resistance. Bulk segregant analysis (BSA) of LMPG-6/PI 626573 F2 progeny determined resistance was conferred by a single dominant gene given the provisional designation SrWLR. The BSA identified nine microsatellite (SSR) markers on the long arm of chromosome 2B associated with the resistant phenotype. Fifteen polymorphic SSRs, including the nine identified in the BSA, were used to produce a linkage map of chromosome 2B; positioning SrWLR between the SSRs GWM47 and WMC332. This region has been reported to contain the wheat stem rust resistance genes Sr9 and SrWeb, the latter conferring resistance to Pgt race TTKSK. The 9,000 marker Illumina Infinium iSelect SNP assay was used to further saturate the SrWLR region. The cosegregating SNP markers IWA6121, IWA6122, IWA7620, IWA8295, and IWA8362 further delimited the SrWLR region distally to a 1.6 cM region. Future work will focus on the positional cloning of SrWLR and the relation of SrWLR to other resistance genes in the region.