Location: Cereal Disease LabTitle: Genetic mapping of stem rust resistance to Puccinia graminis f. sp. tritici race TRTTF in the Canadian wheat cultivar 'Harvest'
|HIEBERT, COLIN - Agriculture And Agri-Food Canada|
|Rouse, Matthew - Matt|
|JAYAVEERAMUTHU, NIRMALA - University Of Minnesota|
|FETCH, TOM - Agriculture And Agri-Food Canada|
Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2016
Publication Date: 11/10/2016
Citation: Hiebert, C.W., Rouse, M.N., Jayaveeramuthu, N., Fetch, T. 2016. Genetic mapping of stem rust resistance to Puccinia graminis f. sp. tritici race TRTTF in the Canadian wheat cultivar 'Harvest'. Phytopathology. 107:192-197.
Interpretive Summary: Wheat stem rust is a devastating fungal disease of wheat. Emerging strains of the wheat stem rust fungus such as Ug99 and race TRTTF threaten wheat production because of their borad virulence to currently grown wheat varieties. Harvest is a commonly grown spring wheat cultivar that confers resistance to race TRTTF. Genetic mapping with molecuar markers placed resistance to race TRTTF in Harvest on wheat chromosome arm 6AS. Markers closely linked to this resistance gene were assessed on 241 breeding lines and cultivars from the United States, Canada, and Mexico and proved to be predictive of resistance to race TRTTF. The markers closely linked to race TRTTF resistance are suitable for marker-assisted selection in breeding and germplasm development programs. Markers linked to stem rust resistance genes effective to emerging races can be used by wheat breeding programs to develop resistant wheat cultivars.
Technical Abstract: Stem rust, caused by Puccinia graminis Pers.:Pers. f. sp. tritici Eriks. & E. Henn.(Pgt), is a destructive disease of wheat that can be controlled by deploying effective stem rust resistance (Sr) genes. Highly virulent races of Pgt in Africa have been detected and characterized. These include race TRTTF and the Ug99 group of races such as TTKSK. Several Canadian and United States spring wheat cultivars, including the widely grown Canadian cultivar 'Harvest', are resistant to TRTTF. However, the genetic basis of resistance to TRTTF in Canadian and United States spring wheat cultivars is unknown. The objectives of this study were to determine the number of Sr genes involved in TRTTF resistance in 'Harvest', genetically map the resistance with DNA markers, and use markers to assess the distribution of that resistance in a panel of Canadian cultivars. A doubled haploid (DH) population was produced from the cross LMPG-6S/Harvest. The DH population was tested with race TRTTF at the seedling stage. Of 92 DH progeny evaluated, 46 were resistant and 46 were susceptible which perfectly fit a 1:1 ratio indicating a single Sr gene was responsible for conferring resistance to TRTTF in 'Harvest'. Mapping with SNP and SSR markers placed the resistance gene distally on the chromosome 6AS genetic map, which corresponded to the location reported for Sr8. SSR marker gwm459 and 30 co-segregating SNP markers showed the closest linkage, mapping 2.2 cM proximal to the Sr gene. Gene Sr8a confers resistance to TRTTF and may account for the resistance in 'Harvest'. Testing a panel of Canadian wheat cultivars with four SNP markers closely linked to resistance to TRTTF suggested that the resistance present in 'Harvest' is present in many Canadian cultivars. Two of these SNP markers were also predictive of TRTTF resistance in a panel of 241 spring wheat lines from the United States, Canada, and Mexico. The data also suggested that SrCad, a gene that confers resistance to Ug99 races of Pgt, may also contribute resistance to TRTTF in some Canadian wheat cultivars.