Location: Cereal Crops ResearchTitle: Identification and mapping of Sr46 from Aegilops tauschii accession CIae 25 conferring resistance to race TTKSK (Ug99) of wheat stem rust pathogen Author
|Yu, Guotai - North Dakota State University|
|Zhang, Qijun - North Dakota State University|
|Rouse, Matthew - Matt|
|Zhong, Shaobin - North Dakota State University|
|Rasmussen, Jack - North Dakota State University|
|Lagudah, Evans - Commonwealth Scientific And Industrial Research Organisation (CSIRO)|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2014
Publication Date: 12/19/2014
Publication URL: http://handle.nal.usda.gov/10113/60599
Citation: Yu, G., Zhang, Q., Friesen, T.L., Rouse, M.N., Jin, Y., Zhong, S., Rasmussen, J.B., Lagudah, E.S., Xu, S.S. 2015. Identification and mapping of Sr46 from Aegilops tauschii accession CIae 25 conferring resistance to race TTKSK (Ug99) of wheat stem rust pathogen. Theoretical and Applied Genetics. 128:431-443.
Interpretive Summary: Bread wheat is a hexaploid species with the A, B, and D genomes. Goatgrass species Aegilops tauschii is the D-genome donor of bread wheat and it is a rich source of genes for resistance to many diseases and insects of wheat. Here, we report the identification of a gene in Aegilops tauschii line CIae 25 for resistance to the Ug99 race group of stem rust pathogen and the development of molecular markers for the gene. In this study, a population of progenies was developed from a cross between Aegilops tauschii lines CIae 25 (resistant) and AL8/78 (susceptible). A total of 710 plants from this population were first evaluated for resistance to stem rust at the seedling stage and then 179 susceptible plants were selected as the mapping population to identify the molecular markers linked to the gene. The results showed that CIae 25 carries a single dominant gene for resistance to stem rust. Based on the marker analysis, we mapped the gene to the short arm of chromosome 2D. A survey on the origin of CIae 25 and its resistance response to multiple races of the stem rust pathogen indicate that the gene in CIae 25 is Sr46, which has not been reported in literature. Five new molecular markers (designated as Xrwgs33 to Xrwgs37) were then developed for the gene region based on the expressed sequence of genes mapped to the chromosomal region. The marker analysis indicated that three markers that are closely-linked to Sr46 can be used to select the gene in wheat breeding. Although Sr46 is designated in the Catalogue of Gene Symbol in Wheat, it has not been reported in the literature. Therefore, this study serves as the first report on identification and characterization of Sr46.
Technical Abstract: The race TTKSK (Ug99) of Puccinia graminis f. sp. tritici, the casual pathogen for wheat stem rust, is currently a major threat to global wheat production. To confine this threat, researchers across the world have been devoted to identifying TTKSK-resistant genes. Here, we report the identification of a stem rust resistance gene in Aegilops tauschii accession CIae 25 that confers resistance to TTKSK and the development of molecular markers for the gene. An F2 population of 710 plants from a cross between Ae. tauschii accessions CIae 25 (resistant) and AL8/78 (susceptible) were first evaluated against race TPMKC. A set of 14 resistant and 116 susceptible F2:3 families from the F2 plants were then evaluated for their reactions to TTKSK. Based on the tests, 179 homozygous susceptible F2 plants were selected as the mapping population to identify the simple sequence repeat (SSR) markers linked to the gene by bulk segregant analysis. A single dominant gene for resistance to both TTKSK and TPMKC was identified and mapped to the deletion bin 2DS5-0.47-1.00 on chromosome arm 2DS. A survey on the origin of CIae 25 and its race specificity indicated that the gene in CIae 25 is Sr46, which has not been reported in literature. Five sequence tagged site markers (Xrwgs33 to Xrwgs37) were developed for the gene region using the expressed sequence tags mapped to the bin. The marker validation indicated that three closely-linked markers Xgwm210, Xwmc111, and Xrwgs33 can be used for marker assisted selection of Sr46 in wheat breeding programs.