Location: Cereal Disease LabTitle: Resistance to Ug99 stem rust in six bread wheat cultivars maps to chromosome 6DS Author
|Rouse, Matthew - Matt|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/4/2013
Publication Date: 10/13/2013
Citation: Lopez-Vera, E.E., Nelson, S., Singh, R.P., Basnet, B.R., Haley, S.D., Bhavani, S., Huerta-Espino, J., Xoconostle-Cazares, B., Ruiz-Medrano, R., Rouse, M.N., Singh, S. 2013. Resistance to Ug99 stem rust in six bread wheat cultivars maps to chromosome 6DS. Theoretical and Applied Genetics. 127:231-239. Interpretive Summary: Over 80% of wheat area worldwide is currently grown to wheat varieties that are susceptible to the virulent Ug99 strain of the stem rust fungus. Wheat lines Niini, Tinkio, Coni, Pfunye, Blouk and Ripper were resistant to Ug99. We found that each of these wheat lines has a single gene that provides resistance to Ug99. We identified the chromosome location of the gene in each of these lines. We also identified molecular markers linked to the resistance gene in each of these lines. Our results provide valuable molecular marker and genetic information for developing Ug99 resistant wheat varieties for wheat breeding programs in the United States and internationally.
Technical Abstract: Over 80% of wheat area worldwide is currently grown to varieties that are susceptible to the Ug99 race group of the stem rust fungus. Wheat lines Niini, Tinkio, Coni, Pfunye, Blouk and Ripper were resistant to Ug99 at the seedling and adult plant stages. We mapped stem rust resistance in populations derived from crosses of a susceptible parent with each of the resistant lines. The segregation of resistance in each population indicated the presence of a single gene. The resistance gene in Niini mapped to the short arm of chromosome 6D and was flanked by SSR markers Xcfd49 and Xbarc183 at distances of 3.9 cM and 8.4 cM proximal and distal, respectively. The chromosome location of this resistance was validated in three other populations PBW343/Coni, PBW343/Tinkio and Cacuke/Pfunye. Resistance initially postulated to be conferred by gene SrTmp in Blouk and Ripper was also linked to Xcfd49 and Xbarc183 on 6DS, however mapped proximal to Xbarc183 at a similar position to previously mapped genes Sr42 and SrCad. Based on variation in marker alleles it is possible that Niini, Pfunye, and Blouk may carry different resistance genes/alleles. Further studies are needed to determine the allelic relationships between the various resistance genes located on chromosome arm 6DS. Our results provide valuable molecular marker and genetic information for developing Ug99 resistant wheat varieties in diverse germplasm.