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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Publications at this Location » Publication #347289
Title: Mapping and characterization of wheat stem rust resistance genes SrTm5 and Sr60 from Triticum monococcum

Author
item CHEN, SHISHENG - University Of California, Davis
item GUO, YAN - University Of California, Davis
item BRIGGS, JORDAN - University Of Minnesota
item DUBACH, FELIX - University Of California, Davis
item Chao, Shiaoman
item ZHANG, WENJUN - University Of California, Davis
item Rouse, Matthew
item DUBCOVSKY, JORGE - University Of California, Davis

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2017
Publication Date: 11/21/2017
Publication URL: https://handle.nal.usda.gov/10113/5900048
Citation: Chen, S., Guo, Y., Briggs, J., Dubach, F., Chao, S., Zhang, W., Rouse, M.N., Dubcovsky, J. 2017. Mapping and characterization of wheat stem rust resistance genes SrTm5 and Sr60 from Triticum monococcum. Theoretical and Applied Genetics. 131(3):625-635. https://doi.org/10.1007/s00122-017-3024-z.
DOI: https://doi.org/10.1007/s00122-017-3024-z

Interpretive Summary: The emergence and spread of new virulent races of the wheat stem rust pathogen, including the TTKSK (Ug99) race group, is a serious threat to global wheat production. In this study, we mapped and characterized two stem rust resistance genes from diploid wheat. We mapped SrTm5, a previously postulated gene effective to race TTKSK, on chromosome arm 7AmL completely linked to Sr22. SrTm5 displayed a different race specificity compared to Sr22 indicating that they are distinct. Characterization of the segregating populations with Pgt race QFCSC revealed an additional resistance gene on chromosome arm 5AmS that was assigned the official name Sr60. This gene was also effective against races QTHJC and SCCSC but not against TTKSK. Using two large mapping populations, we mapped Sr60 within a 0.44 cM interval flanked by sequenced-based markers GH724575 and CJ942731. The discovery of SrTm5 as effective to Ug99 may facilitate the improvement of Ug99 resistance in United States wheat varieties. Ug99 resistant wheat varieties would protect United States wheat production from yield loss if a Ug99 epidemic were to occur in the United States.

Technical Abstract: The emergence and spread of new virulent races of the wheat stem rust pathogen (Puccinia graminis f. sp. tritici; Pgt), including the TTKSK (Ug99) race group, is a serious threat to global wheat production. In this study, we mapped and characterized two stem rust resistance genes from diploid wheat Triticum monococcum accession PI 306540. We mapped SrTm5, a previously postulated gene effective to race TTKSK, on chromosome arm 7AmL completely linked to Sr22. SrTm5 displayed a different race specificity compared to Sr22 indicating that they are distinct. Sequencing of the Sr22 homolog in PI 306540 revealed a novel haplotype. Characterization of the segregating populations with Pgt race QFCSC revealed an additional resistance gene on chromosome arm 5AmS that was assigned the official name Sr60. This gene was also effective against races QTHJC and SCCSC but not against TTKSK. Using two large mapping populations (total 4,046 gametes), we mapped Sr60 within a 0.44 cM interval flanked by sequenced-based markers GH724575 and CJ942731. These two markers delimit a 54.6 kb region in Brachypodium distachyon chromosome 4 and a 430 kb region in the Chinese Spring reference genome. Both regions include a leucine-rich repeat protein kinase (LRRK123.1) that represents a potential candidate gene. Three CC-NBS-LRR genes were found in the Brachypodium region but not in the wheat genome. We are currently developing a Bacterial Artificial Chromosome library of PI 306540 to determine which of these candidate genes are present in the T. monococcum genome and to complete the cloning of this gene.