Genome and chromosome disposition at somatic metaphase in a Hordeum x Psathyrostachys hybrid

The distribution of chromosomes by centromeres and telomeres was studied in 100 squashed, somatic metaphases of a Hordeum vulgare (2n = 2x= 14) x Psathyrostachys fragilis (2n = 2x= 14) hybrid. The chromosomes and chromosome arms were individually identified in each of the parental genomes by their Giemsa C-banding patterns. The P. fragilis chromosomes were more widely scattered on the metaphase plate, and were therefore, also, on average located further from the cell centre than the H. vulgare chromosomes. Within the parental genomes, the only exception from a random distribution of the chromosomes was that the two satellited chromosomes of H. vulgare were located closer to each other and to the cell centre than can be attributed to chance. This association was most clearly expressed for the telomeres of the chromosome arms carrying the satellites. The data suggest that the parental chromosome complements constitute separate units. This was supported by the observation that five cells had their genomes arranged side-by-side.