A STRATEGY FOR DETECTING CHROMOSOME-SPECIFIC REARRANGEMENTS IN RYE

To obtain translocations involving specific chromosomes in rye, a line in which chromosome 1R has large C-bands on its two telomeres but whi ch lacks C-bands (or has very small ones) on the telomeres of the rema ining chromosomes was used. About 6% of the plants produced using poll en from irradiated (1.2 krad (1 rad = 10 mGy)) spikes of this line pos sessed structural changes involving the labeled chromosome. These aber rations included translocations, ring chromosomes, isochromosomes, and telocentrics. It is concluded (i) that all nonlabeled chromosomes hav e the same probability of participating in reciprocal translocations w ith the labeled chromosome, 1R, and (ii) that most induced reciprocal translocations involved exchanges of chromosome segments of approximat ely equal length. The use of lines having the appropriate combination of telomeric C-bands improves the efficiency of obtaining reciprocal t ranslocations involving specific chromosomes that could be used in the construction of detailed physical maps.