Chromosome pairing at meiosis in hybrids between aeg/lops and secale species: A study by in situ hybridisation using cloned dna

Abstract

The meiotic pairing behaviour in hybrids between Aegilops and Secale species has been examined using the technique of in situ hybridisation of tritium labelled RNA copies of cloned DNA sequences to distinguish the chromosomes. The probe used was a 480 b.p. repeat which is specific to rye, enabling the rye chromosomes to be clearly identified. It was shown that in diploid hybrids between Ae. caudata or Ae. comosa and S. cereale, pairing is mostly of the allosyndetic, Aegilops/rye type, although some autosyndetic associations also occur. In the triploid hybrid between Ae. coluinnaris and rye however, pairing is predominantly limited to the Aegilops chromosomes. Examination of the patterns of labelling shown by the hybridisation of the 480 b.p. probe suggested that pairing orientation and chiasma formation are not at random. This was confirmed by in situ hybridisation of the chromosome specific, ribosomal RNA gene probe to the meiotic chromosomes of the F1 hybrid between Ae. comosa and S. cereale. © 1980 The Genetical Society of Great Britain.