RELATIONSHIPS IN THE GENUS HORDEUM - GIEMSA C-BANDED KARYOTYPES

Giemsa C-banded karyotypes of the 32 Hordeum L. species incl. all subspecies and cytotypes divide them into four groups by chromosome banding patterns. Most taxa have a rather similar pattern with a number of more or less randomly disposed C-bands at centromeric, intercalary, and distal positions. This agrees with their grouping with a common genome, H. H. brevisubulatum s.l. is normally grouped with genome H, but the banding patterns of the five subspecies deviate by having a low number of centromeric and intercalary bands only (patterns vary from having no to very conspicuous C-bands at the telomeres). H. bulbosum has most C-bands at the centromeres, and H. vulgare, most C-bands at centromeric and juxtacentromeric positions. The overall resemblance of the C-banding patterns of H. bulbosum and H. vulgare supports that both carry thc same genome, I. H. marinum and H. murinum each have a deviating karyotype. The corresponding genomes are preliminarily referred to as 'X' and 'Y'. In combination with chromosome number, and number and morphology of marker chromosomes, the C-banded karyotypes of a number of species are sufficiently distinct to bc of use for identification and the study of relationships. Most Hordeum species of the Americas have similar C-banded karyotypes at the respective ploidy level, questioning the biological relevance of referring them to different sections.