Development of arm specific RAPD markers for rye chromosome 2R in wheat

Rye (Secale cereale L.) chromosome 2R carries several genes for resistance to biotic and abiotic stresses, which could be used in wheat (Triticum aest ivum L,) improvement. To make these genes accessible in breeding, transloca tions of 2R to wheat chromosome 2B have been generated. To compensate for t he lack of clearly identifiable cytological markers on chromosome 2R, rando m amplified polymorphic DNAs (RAPDs) were employed as markers. Wheat lines homozygous for centric translocations 2RS.2BL and 2BS.2RL were screened wit h 489 primers, resulting in 65 clear and reproducible RAPD polymorphisms. T o assign the polymorphisms to individual arms of chromosomes 2R and 2B, the arms of the translocations were separated by centric misdivision and the r esulting progeny with desired chromosome constructs were rescreened, As a r esult, 17 markers were assigned to chromosome arm 2RS, 15 to 2RL, and the r emaining 33 most likely located on 2B, Preliminary mapping studies (not sho wn here) have indicated that some of these markers are evenly distributed a long the chromosome arms. These markers should be useful for the localizati on of translocation breakpoints in recombinant wheat-rye chromosomes.