Not available – first paragraph follows: Success in hybridizing wild with cultivated species ultimately depends on the ability of the alien chromosomes to pair and recombine with the chromosomes of the crop species at meiosis. In bread wheat, pairing and thus recombination normally occur only between identical or homologous chromosomes and not, unfortunately, between a wheat chromosome and an alien chromosome. However, increasing knowledge of the components of the genetic system controlling pairing has made it possible to manipulate them to achieve pairing between nonhomologous chromosomes. A major advantage of such induced pairing is that it usually occurs between closely related but not homologous chromosomes—termed homoeologues. Recombination of genetic material between homoeologues is likely to result in genetically more balanced chromosomes than if recombination were between unrelated chromosomes.