Molecular cytogenetic characterization and SSR marker analysis of a leaf rust resistant wheat line carrying a 6G(6B) substitution from Triticum timopheevii (Zhuk.)

A disease (powdery mildew, leaf rust) resistant line was selected from the progenies of a Triticum aestivum x Triticum timopheevii amphiploid produced at Martonvasar. This line was previously identified with C-banding as a 6G(6B) substitution. In order to detect the 6G chromosome in a wheat background, fluorescence in situ hybridization (FISH) and microsatellite marker analysis were used. Ten microsatellite markers of the 43 tested generated PCR products that were polymorphic between chromosomes 6B and 6G, and four showed length-polymorphism. The FISH hybridization pattern of 6G from T. timopheevii was identified using a combination of four repetitive DNA probes (Afa-family, pSc119.2, pTa71, (GAA)(7)). Genomic in situ hybridization (GISH) technique, capable of labelling the A(t) and G genomes separately, was used on the same slides to differentiate the A(t) and G genomes in T. timopheevii. The A(t) and G genomes of T. timopheevii were grouped on the basis of the GISH patterns and a cyclic intergenomic translocation involving 6A(t)-1G-4G was detected in T. timopheevii accession TRI667. The presence of 6G in the substitution line was demonstrated using FISH with the four repetitive DNA probes. Chromosome 6G was clearly identified and its FISH pattern was different from that of 6B in the parental wheat cultivar Fleischmann-481. According to field tests, the 6G(6B) substitution line has resistance to leaf rust.