Composition and random elimination of paternal chromosomes in a large population of wheat × barley (Triticum aestivum L. × Hordeum vulgare L.) hybrids.

KEY MESSAGE: Statistical analysis of the chromosomal composition in a population of 210 primary plants regenerated from two intergeneric wheat-barley cross combinations revealed the random nature of uniparental elimination for barley chromosomes. Uniparental chromosome elimination is a common process in interspecific and intergeneric cereal hybrids. To characterize the frequency of paternal chromosomes, a population of 218 independent green plants was generated from two wheat (♀) × barley (♂) cross combinations via embryo rescue. The chromosomal composition of 210 primary plants was analyzed with chromosome-specific DNA markers representing all seven barley chromosomes. The analysis revealed an equal proportion of haploid and full hybrids (20.5% and 19.5%, respectively), while the rest of the population contained hypoploids (partial hybrids) with no preference for any possible numbers (one to six) of barley chromosome additions. Contrary to the previous reports, there was no statistical bias or preferential elimination for any individual barley chromosome (1H-7H) in this population. The reasons for the apparent contradiction and the implications of the above findings for cereal breeding are discussed.