2011 Field Crops Rust Symposium:
QTL Mapping of Resistance to Ethiopian Stem Rust Races Including Ug99 in Durum Wheat (Triticum durum Desf.)
Presenting Author: J. K. HAILE (1)
Coauthors: M. S. Röder (1), M. M. Nachit (2), K. Hammer (3), A. Badebo (4)
Affiliations: (1) Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany; (2) ICARDA, ICARDA BIGM, Durum Improvement Program, Aleppo, Syria; (3) Dept. of Agrobiodiversity, Institute of Crop Sciences, University of Kassel, Witzenhausen, Germany; (4) Ethiopian Institute of Agricultural Research, Debre-Zeit Agricultural Research Centre, Debre-Zeit, Ethiopia
Stem rust caused by Puccinia graminis f. sp. tritici was historically one of the most destructive diseases of wheat worldwide. The evolution and rapid migration of race TTKSK (Ug99) and its derivatives, first detected in Uganda in 1999, is of an international concern due to the virulence of these races to widely used stem rust resistance genes. In attempts to identify quantitative trait loci (QTL), regions linked with resistance to the stem rust race, including Ug99 and its derivatives, 95 recombinant inbred lines (RILs) developed from a cross between two durum wheat varieties, ‘Kristal’ × ‘Sebatel’, were evaluated. Seven field trials at two locations were carried out in main and off-season. In addition to the natural infection, the population was also artificially inoculated with urediniospores of stem rust race Ug99 and a mixture of highly virulent races from Ethiopia. A genetic map was constructed based on 209 polymorphic SSR and two STS loci. Using composite interval mapping, seven major and consistent QTLs with additive effects for resistance to currently available stem rust races from Ethiopia were identified on chromosomes 1AL, 2AS, 3BS, 4BL, 6AL, 7AS, and 7BL. Additionally, on chromosome 7AL, a minor QTL was identified in the region where Sr22 is reported. A minor consistent QTL was also identified on the long arm of chromosome 5B. These results suggest that durum wheat resistance to the Ethiopian races of stem rust is oligogenic and that there is potential to identify previously uncharacterized resistance genes with minor effects. The SSR markers that are closely linked to the consistent QTLs can be used for MAS for stem rust resistance in durum wheat.