Genomic constitution and intergenomic translocations in the Elymus dahuricus complex revealed by multicolor GISH

Multicolor genomic in situ hybridization was used to investigate the genomic constitution and intergenomic translocations in the Elymus dahuricus complex. The genomic constitution of species of the E. dahuricus complex was confirmed as StYH. H/Y and H/St intergenomic translocations were identified in the present study, with 7H and 1Y chromosomes involved in reciprocal translocations for all the accessions investigated in the complex. We propose that the translocations in the E. dahuricus complex are species-specific, associated with allopolyploidy, and may serve as important structural alterations for allopolyploid stability. Furthermore, they may help to restore fertility and nucleocytoplasmic compatibility in a newly formed polyploid and facilitate the successful establishment of E. dahuricus as a stable species. It was found that more chromosomes were involved in translocations and more types of intergenomic translocations were observed in the high altitude (4150 m) population Y 2228 than in populations from relatively lower altitudes (2600-3800 m). We speculate that more complicated genomic changes were associated with escalating altitudes in the Tibetan Plateau. These genomic changes contribute to promote the genetic variability and enable the newly formed allopolyploids to adapt to more changeable and harsher environments during the evolution of a polyploid species, thus facilitating their rapid and successful establishment in nature.