Abstract
Key messageStatistical 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.
Highlights
Complete or partial uniparental genome elimination during initial mitotic divisions in embryos of ultrawide sexual hybrids is a general phenomenon in the plant kingdom (Ishii et al 2016)
Uniparental chromosome elimination is well described for cereal plant species, where it is primarily, though not exclusively, confined to the paternal genome donor (Houben et al 2011; Zhao et al 2013)
Chromosome elimination during the embryogenesis of cultivated barley (Hordeum vulgare) × Hordeum bulbosum hybrids is associated with the formation of micronuclei, abnormally condensed chromatin, and chromosome fragments (Gernand et al 2006)
Summary
Complete or partial uniparental genome (or chromosome) elimination during initial mitotic divisions in embryos of ultrawide (interspecific and intergeneric) sexual hybrids is a general phenomenon in the plant kingdom (Ishii et al 2016). It represents a key element in the protection of genome integrity from “genome shock” (McClintock 1984) as a result of hybridization between unusually distant partners. Chromosome elimination during the embryogenesis of cultivated barley (Hordeum vulgare) × Hordeum bulbosum hybrids is associated with the formation of micronuclei, abnormally condensed chromatin, and chromosome fragments (Gernand et al 2006). Chromosome elimination is not always due to malfunction of the kinetochores binding to the microtubuli and to the failure of the sister
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