MOLECULAR CYTOGENETIC CHARACTERIZATION OF BROMEGRASSES

Dept. of Agronomy, University of Nebraska-Lincoln, Lincoln, NE 68583-0915 USA

Bromegrasses belong to the genus Bromus L. and there are more than 100 species in this genus with a wide geographic distribution. Previous cytogenetic studies of Bromus were limited to chromosome counts and construction of karyotypes based on feulgen staining. Our objectives are to characterize and classify genomes of four bromegrass species (Bromus inermis spp. inermis, Bromus inermis spp. pumpellianus, Bromus biebersteinii, and Bromus riparius) and to determine genomic relationships among them, using moleculer cytogenetic approach. We have standardized a C-banding procedure for these species. We have made a karyotype of a diploid species (Bromus riparius) based on C-banding patterns, centromeric location and chromosome size. The haploid chromosome complement of this species was composed of four metacentric, two sub-metacentric and one satellite chromosome. All chromosomes had clearly visible C-bands, and 5 of the 7 chromosomes could be identified. The remaining two chromosomes were similar in size and C-banding patterns but can be distinguished by morphology. We are in the process of making karyotypes of Bromus species, which have higher ploidy levels.