Molecular Analysis of the Genomes of Wide Hybrids in Cereals

Abstract

The structural organization of various highly repetitive DNA sequences from barley (H. uulgare) and rye (S. cereale) were studied by blot-hybridization in hybrids of Hordeum x Secale, the tri-generic hybrid H. uulgare x T. timopheeuii x S. cereale, and regenerants of the tri-generic hybrid after in vitro cultivation. The set of repetitive DNA sequences used proved to be valuable as molecular markers for the analysis of the hybrid genetic material. Use of the probes permitted the identification of each generation during wide crossing and following backcrosses. Structural rearrangements of certain repetitive sequences were revealed, 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 hybrid H. geniculatum x S. cereale, once in a regenerant of the tri-generic hybrid. When the hybrid H. geniculaium x S. cereale was backcrossed to, S. cereale, new hybridization fragments, characteristic of the wild barley species H. jubaium were discovered. Changes in the structural organization of several repetitive sequences are described, while the non-random nature of these rearrangements is discussed.