MOLECULAR ANALYSIS OF THE GENOMES OF WIDE HYBRIDS IN CEREALS

The structural organization of various highly repetitive DNA sequences from barley (H. vulgare) and rye (S. cereale) were studied by blot-hy bridization in hybrids of Hordeum x Secale, the tri-generic hybrid H. vulgare x T. timopheevii x S. cereale, and regenerants of the tri-gene ric hybrid after in vitro cultivation. The set of repetitive DNA seque nces used proved to be valuable as molecular markers for the analysis of the hybrid genetic material. Use of the probes permitted the identi fication of each generation during wide crossing and following backcro sses. Structural rearrangements of certain repetitive sequences were r evealed, which were probably generated by such stress factors as wide crosses and in vitro cultivation. New RFLP patterns, not found in the parental species, arose on two occasions, once in a backcross of the h ybrid H. geniculatum x S. cereale, once in a regenerant of the tri-gen eric hybrid. When the hybrid H. geniculatum x S. cereale was backcross ed to S. cereale, new hybridization fragments, characteristic of the w ild barley species H. jubatum were discovered. Changes in the structur al organization of several repetitive sequences are described, while t he non-random nature of these rearrangements is discussed.