Rye chromosome variability in wheat-rye addition and substitution lines

In a study of polymorphism and stability in rye chromosomes, three rye vari eties and the sets of wheat-rye addition and substitution lines were compar ed using two non-homologous highly repetitive DNA families, pSc200 and pSc2 50. The rye varieties, Petkus, Imperial and Onohoiskaya, showed polymorphis m for the presence and the size of the pSc200 in-situ hybridization signals on chromosome pairs, 2R, 4R and 7R, and the pSc250 signals on chromosomes, 5R, 6R and 7R. Chromosome 1R was heteromorphic within the Onohoiskaya vari ety. Differences in the distribution of chromosome polymorphisms imply that intervarietal changes to these highly repetitive DNA families occurred ind ependently, despite their juxtaposition or even overlapping locations in su btelomeric heterochromatic regions. In the set of Saratovskaya 29 wheat/Ono hoiskaya substitution lines, only chromosome 2R was altered relative to its counterpart in the parental rye variety due to amplification of the pSc250 signal on the long arm, although this did not exceed intervarietal polymor phism. In the set of Chinese Spring wheat/ Imperial addition lines, only tw o Imperial chromosomes, 4R and 6R, were unchanged. We detected the loss of one or both rye homologous chromosomes, the loss of one arm, and the deleti on of subtelomeric heterochromatin accompanied by the loss of the pSc200 si gnal. The results show that Saratovskaya 29/Onohoiskaya chromosome substitu tion lines possess increased chromosome stability compared with Chinese Spr ing/Imperial addition lines.