Polymerase chain reaction based mapping of rye involving repeated DNA sequences

A novel type of polymerase chain reaction (PCR) marker was developed for the mapping of cereal rye (Secale cereale). Primer pairs were synthesized targeting the insertion sites of three individual copies of the R173 family of rye specific repeated DNA sequences. While one primer was derived from a sequence within the respective R173 element, the second primer corresponded to a flanking region. The complex banding patterns obtained in rye allowed not only the mapping of the three R173 elements to certain chromosome regions of 1RS (the short arm of rye chromosome 1) but also the mapping of an additional 3-10 easily identifiable bands per primer pair to other rye chromosomes. Linkage mapping of a polymorphic 1R band derived from three rye cultivars demonstrated the presence of nonallelic, dominant markers in two independent crosses. Because of the high copy number of the R173 family (15,000 copies per diploid rye genome), its dispersion over the entire length of all chromosomes and the high number of markers obtained per primer pair, PCR markers based on the R173 family provide an almost unlimited source for well-spaced markers in rye mapping.