Production and identification of new structural chromosome mutations in barley (Hordeum vulgare L.).

A total of 52 reciprocal translocations and 9 pericentric inversions were induced and identified in both standard and cytologically marked barley karyotypes using gamma-rays as the clastogenic agent. An analysis based upon Giemsa N-banding patterns and arm length measurements of the reconstructed chromosomes enabled a rather precise cytological localization of intra- and interchange breakpoints. This analysis was significantly facilitated and improved, especially for the identification of pericentric inversions, when the reconstructed karyotype T-1586 was used as starting material. The majority, if not all, of the aberration breakpoints proved to be localized in interband regions or in medial and terminal parts of the chromosomes, i.e., in regions which are deficient in constitutive heterochromatin. A great number of the structural mutations produced in this study contain specific cytological markers covering nearly all of the chromosomes of barley karyotype. This material might be of considerable interest in solving various problems of barley cytogenetics and chromosome engineering and especially in constructing a physical map of barley genome.