Intrachromosomal mapping of chromatid aberrations induced by restriction endonucleases in barley

The intrachromosomal distribution patterns of chromatid aberrations induced by the restriction endonucleases HpaII, MspI and HaeIII in a multireconstructed barley karyotype were analysed. All of these endonucleases, which differ with respect to their DNA recognition sequences but produce only one type of DNA damage, showed nearly the same pattern of localized chromosome breakage. The most pronounced aberration hot spots proved to be the loci of transcriptionally active and condensed, inactive, rDNA. Possible mechanisms involved in the specific distribution of induced aberrations along the distinct chromosomal regions are discussed.