[Genetic control of the wheat Triticum monococcum L. resistance to powdery mildew]

Using hybrid analysis and test-clone method, 102 accessions of Triticum monococcum L. from the collection of the Vavilov All-Russia Institute of Plant Industry have been studied. This species of wheat has been found to by considerably polymorphic with respect to the resistance to the fungus Erysiphe graminis DC. f. sp. tritici Marchal. causing powdery mildew. The resistance of most accessions to the fungus population and clones is determined by dominant genes. In rare cases, the resistance was determined by recessive genes or one, two, or three oligogenes. A group of einkorn wheat accessions has been found in which the resistance to powdery mildew was determined by the same dominant factor or different but closely linked ones. Recessive resistance genes of T. monococcum differ from the recessive gene pm5 determining the resistance of T. aestivum plants. The genome of T. monococcum contains various genes of resistance to powdery mildew and is a potential source of effective genes to be used when selecting cultivated species of wheat for immunity.

Chromosomal location of a Triticum timopheevii--derived powdery mildew resistance gene transferred to common wheat

A dominant powdery mildew resistance gene introduced from Triticum timopheevii in line 146-155-T of common wheat, Triticum aestivum, was located on chromosome 6B by monosomic analysis. Restriction fragment length polymorphism (RFLP) and microsatellite analyses detected the presence of a T. timopheevii segment, translocated to chromosome 6B, with breakpoints between the loci Xpsr8/Xpsr964 on 6BS and Xpsr154/Xpsr546 on 6BL. The novel powdery mildew resistance gene, which has been designated Pm27, was shown to cosegregate with the microsatellite locus Xpsp3131, which is located on the introgressed T. timopheevii segment. The molecular data confirm the location of Pm27 on the translocated 6B chromosome.