Mapping and characterization of two stem rust resistance genes derived from cultivated emmer wheat accession PI 193883
Two stem rust resistance genes identified on chromosome arms 2BL and 6AL of the cultivated emmer wheat accession PI 193883 can be used for protecting modern varieties against Ug99 strains.
The wheat research community consistently strives to identify new genes that confer resistance to stem rust caused by the fungal pathogen Puccinia graminis f. sp. tritici Eriks & E. Henn (Pgt). In the current study, our objective was to identify and genetically characterize the stem rust resistance derived from the cultivated emmer accession PI 193883. A recombinant inbred line population developed from a cross between the susceptible durum wheat line Rusty and PI 193883 was genotyped and evaluated for reaction to Pgt races TTKSK, TRTTF, and TMLKC. Two QTLs conferring resistance were identified on chromosome arms 2BL (QSr.fcu-2B) and 6AL (QSr.fcu-6A). The stem rust resistance gene (Sr883-2B) underlying QSr.fcu-2B was recessive, and based on its physical location it is located proximal to the Sr9 region. QSr.fcu-6A was located in the Sr13 region, but PI 193883 is known to carry the susceptible haplotype S4 for Sr13, indicating that the gene underlying QSr.fcu-6A (Sr883-6A) is likely a new allele of Sr13 or a gene residing close to Sr13. Three IWGSC scaffold-based simple sequence repeat (SSR) and two SNP-based semi-thermal asymmetric reverse PCR (STARP) markers were developed for the Sr883-2B region, and one STARP marker was developed for Sr883-6A. Sr883-2B was epistatic to Sr883-6A for reaction to TTKSK and TRTTF, and the two genes had additive effects for TMLKC. These two genes and the markers developed in this research provide additional resources and tools for the improvement in stem rust resistance in durum and common wheat breeding programs.
We thank Shiaoman Chao and Mary Osenga, at the USDA-ARS Small Grains Genotyping Lab at Fargo, ND, for assistance in genotyping the mapping population using the wheat 90 K SNP iSelect assays and Danielle Holmes for technical support in stem rust evaluations. This research was supported in part by funds to S. S. X. and M. N. R. provided through grants from the Bill & Melinda Gates Foundation and UK Department for International Development to Cornell University for the Durable Rust Resistance in Wheat (DRRW) and Delivering Genetic Gain in Wheat (DGGW) Projects. It was also funded by the US Department of Agriculture–Agriculture Research Service (USDA-ARS) Current Research Information System (CRIS) Projects Nos. 3060-21000-038-00D and 5062-21220-023-00-D.
Author contributions statement
JF, SX, MR, YJ, and PO initiated the study and designed the experiment. QZ, DK, and SX developed the mapping populations. JS, DK, and TF conducted stem rust test using TMLKC and other North American races. MR, PO, and YJ conducted the stem rust tests using TTKSK and TRTTF. JS, YL, JF, and SX developed STARP and SSR markers. JS, PM, and JF conducted linkage analysis of stem rust resistance. JS and JF wrote the manuscript, and all authors contributed to the final version.
Conflict of interest
The authors declare that they have no conflicts of interest.
The experiments were performed in compliment with the current laws of the United States of America.
- Aoun M, Kolmer JA, Rouse MN, Elias EM, Breiland M, Bulbula WD, Chao S, Acevedo M (2019) Mapping of novel leaf rust and stem rust resistance genes in the Portuguese durum wheat landrace PI 192051. Genes Genom Genet 9:2535–2547Google Scholar
- Klindworth DL, Niu Z, Chao S, Friesen TL, Jin Y, Faris JD, Cai X, Xu SS (2012) Introgression and characterization of a goatgrass gene for a high level of resistance to Ug99 stem rust in tetraploid wheat. Genes Genomes Genet 2:665–673Google Scholar
- Newcomb M, Olivera PD, Rouse MN, Szabo LJ, Johnson J, Gale S, Luster DG, Wanyera R, Macharia G, Bhavani S, Hodson D, Patpour M, Hovmøller MS, Fetch TG Jr, Jin Y (2016) Kenyan isolates of Puccinia graminis f. sp. tritici from 2008 to 2014: virulence to SrTmp in the Ug99 race group and implications for breeding programs. Phytopathology 106:729–736CrossRefGoogle Scholar
- Olivera P, Newcomb M, Szabo LJ, Rouse M, Johnson J, Gale S, Luster DG, Hodson D, Cox JA, Burgin L, Hort M, Gilligan CA, Patpour M, Justesen AF, Hovmøller MS, Woldeab G, Hailu E, Hundie B, Tadesse K, Pumphrey M, Singh RP, Jin Y (2015) Phenotypic and genotypic characterization of race TKTTF of Puccinia graminis f. sp. tritici that caused a wheat stem rust epidemic in southern Ethiopia in 2013–14. Phytopathology 105:917–928CrossRefGoogle Scholar
- Roelfs AP (1978) Estimated losses caused by rust in small grain cereals in the United States 1918–76. United States Department of Agriculture, Agricultural Research Service, Washington DCGoogle Scholar
- Roelfs AP, McVey DV (1975) Races of Puccinia graminis f. sp. tritici in the U.S.A. during 1974. Plant Dis Report 59:681–685Google Scholar
- Saini J, Faris JD, Zhang Q, Rouse MN, Jin Y, Long Y, Klindworth DL, Elias EM, McClean PE, Edwards MC, Xu SS (2018) Identification, mapping, and marker development of stem rust resistance genes in durum wheat ‘Lebsock’. Mol Breed 38:77. https://doi.org/10.1007/s11032-018-0833-y CrossRefGoogle Scholar
- Singh RP, Hodson DP, Jin Y, Lagudah ES, Ayliffe MA, Bhavani S, Rouse MN, Pretorius ZA, Szabo LJ, Huerta-Espino J, Basnet BR, Lan C, Hovmøller MS (2015) Emergence and spread of new races of wheat stem rust fungus: continued threat to food security and prospects of genetic control. Phytopathology 105:872–884CrossRefGoogle Scholar
- Spielmeyer W, Sharp PJ, Lagudah ES (2003) Identification and validation of markers linked to broad-spectrum stem rust resistance gene Sr2 in wheat (Triticum aestivum L.). Crop Sci 43:333–336Google Scholar
- Stakman EC, Stewart DM, Loegering WQ (1962) Identification of physiologic races of Puccinia graminis var. tritici. USDA ARS E-617. U.S. Gov. Print. Off., WashingtonGoogle Scholar