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Molecular cytogenetic characterization of bromegrasses

Metin Tuna, University of Nebraska - Lincoln


Bromus inermis L. is most commonly cultivated bromegrasss species used as a forage crop in North America. The genome structure of Bromus and its relatives is still not resolved. Additional information on the genome structure and relationship of these species to each other will assist plant geneticists in their research. The objectives of this research included the determination of the ploidy level of the accessions of Bromus species (Bromus inermis ssp. inermis , Bromus riparius, Bromus biebersteinii , and Bromus inermis ssp. pumpellianus) and the development of more informative karyotypes using a molecular cytogenetic technique (C-banding) for each of the different ploidy levels to attempt to resolve some of the genomic issues among species. ^ Based on DNA content (pg 2C–1) and verifying chromosome counts, average DNA content and chromosome number of bromegrass species were: 22.62 pg 2C–1 for octaploid B. biebersteinii (2n = 56), 26.07 pg 2C–1 for decaploid B. biebersteinii (2n = 70), 11.74 pg 2C–1 for tetraploid B. inermis ssp. inermis (2n = 28), 22.28 pg 2C–1 for octaploid B. inermis ssp. inermis (2n = 56), 22.72 pg 2C–1 for octaploid B. inermis ssp. pumpellianus (2n = 56), 26.5 pg 2C–1 for decaploid B. inermis ssp. pumpellianus (2n = 70), 6.14 pg 2C –1 for diploid B. riparius (2n = 14), 22.15 pg 2C–1 for octaploid B. riparius (2n = 56) and 26.64 pg 2C–1 for decaploid B. Riparius (2n = 70). ^ C-bands were located mainly at telomeric regions of the chromosomes of the Bromus species. Except four chromosomes of the tetraploid B. inermis, it was possible to distinguish all chromosomes of diploid B. riparius and tetraploid B. inermis and match the pairs of homologous chromosomes based on C-banding patterns, chromosome length and arm ratio. The combination of C-banding patterns, chromosome length and arm ratio also facilitated karyotyping of the octaploid B. inermis and made it possible to make a more informative karyotype than previous karyotypes. These C-banded karyotypes can be used to study relations within the genus Bromus when C-banded karyotypes were made for other species of Bromus. ^

Subject Area

Agriculture, Agronomy|Biology, Molecular|Biology, Genetics

Recommended Citation

Tuna, Metin, "Molecular cytogenetic characterization of bromegrasses" (2000). ETD collection for University of Nebraska - Lincoln. AAI9962069.