| Powdery mildew, caused by Erysiphe graminis f. sp. tritici, is one of the devastating diseases of wheat (Triticum aestivum L. em Thell.). The use of resistant cultivars is the most economical, effective and environmentally safe way to control this disease. Molecular markers tightly linked to resistance genes not only facilitates the identification and mapping of resistance genes, but also can be used for markers-assisted selection (MAS) of resistant lines in breeding programs. MAS greatly enhances the opportunity for gene pyramiding and expedites the process of breeding for resistance. Wild relatives of wheat have a large of resistance resources, and are a rich gene source for disease resistance. The objectives of the present studies were to identify and tag several powdery mildew resistance genes introgressed into wheat from some wild relatives of wheat using microsatellite markers, and using linked microsatellite markers to detect the powdery mildew resistance genes in many advanced lines derived from these wild relatives of wheat. The results will provide useful information for rapidly and effectively using the powdery mildew genes.The resistance genes in 11 tetraploid wheat-Aegilops amphidiploids, T. carthlicum acc. PS5, T. durum ace. DR147, 4 Aegilops accessions and advanced lines Am9/Laizhou953*2 F5 and (DR147/Ael4) //Laizhou953*2 F4 were analyzed by inoculating detached primary leaf segments with a set of 20 differential powdery mildew isolates. By comparisons of the response pattern of differential wheat cultivars or lines to the 20 isolates and pedigree analysis, we deduced that resistancegene Pm4b occurred in line Am9/Laizhou953* FS, and an unknown resistance gene in combination with resistance gene Pm4b occurred in T. carthlicum ace. PS5. Line (DR147/Ael4)//Laizhou953*2 F4 and T. durum aac. DR147 possessed an unknown resistance gene in combination with resistance gene Pm4a. Ae. caudata ace. Ael4 andAe. umbellulata ace. Y39 should carry a novel resistance gene.A dominant major gene conferring resistance to powdery mildew of wheat was identified in a BC2F2 population derived from a cross between amphidiploid Am4 and wheat cv. Bainong3217. The gene originated in T. carthlicum ace. PS5, the tetraploid wheat parent of Am4. Microsatellite marker Xgwm356 was identified to be linked to the gene with a genetic distance of 10.2cM. Based on the location of marker Xgwm356 on wheat chromosome, the gene was located on the wheat chromosome 2AL. Because both the gene and documented gene Pm4b originated from T. carthlicum, and was located on region of wheat chromosome 2AL near the gene Pm4b, it maybe either Pm4b, or a new gene linked to Pm4b. Temporarily, the gene was designated as PmPS5A.A dominant major gene conferring resistance to powdery mildew was identified in a BC3F2 population derived from a cross of amphidiploid Am9 and wheat cv. Laizhou953. The gene originated from T. carthlicum ace. PS5, the tetraploid wheat parent of Am9. Four microsatellite markers Xwmc317, Xgwmlll, Xgwm382 and Xgwm526 were found to be linked to the gene. On a genetic map of the gene and the linked microsatellite markers, the gene was flanked by markers Xwmc317 andXgwm526 at 1.1 cM and 18.1cM, respectively. Markers Xgwmlll and Xgwm382 were mapped on the same side as marker Xwmc317, and linked to the gene with genetic distance of 2.2cM and 4.0cM, respectively. Based on the chromosome location of the linked micro satellite markers in wheat, the gene was located on wheat chromosome 2BL. The gene was different from the gene Pm6 and Pm26 located on wheat chromosome 2B, it should be a novel powdery mildew resistance gene. Temporarily, the gene was designated as PmPSSB. It is proposed that the gene is designated as Pm32.A new gene conditioning resistance to wheat powdery mildew was identified in a BCsFs population derived from a cross of amphidiploid Am9 and wheat cv. "Laizhou953". Microsatellite markers Xgwm296, Xgwm257, and Xgwm319 were identified to cosegregate with the gene. Markers Xgwm257 and Xgwm319 were resistant codom...
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