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

Abstract

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.

Molecular Cytogenetic Characterization of a New Reconstructed Barley Karyotype

“…this approach was successfully applied to map the heterochromatic segments in barley karyotype, since the pericentromeric regions of nearly all chromosomes of this species were found to carry heavy n-bands making it impossible to localize precisely the position of the centromeres directly in Giemsa N-banded plates. As expected, the data concerning the distribution pattern of n-bands along the individual chromosomes, obtained in this study, completely confirmed our results from previous analogous investigations with the parental lines of PK 88-19 (6,8). What is interesting to see on this figure, however, is that the identity of each chromosome of the complement is readily apparent in a routinely stained preparation, thus having no need to use laborious, sophisticated techniques in barley cytogenetic studies.…”

“…clear indications were obtained that the reconstructed chromosomes 1h 5h and 5h 1h have resulted from unequal reciprocal interchange between the long arms of chromosomes 1H and 5H (8). The data obtained from FISH analysis in this study showed that the putative region of the exchange in chromosome 1H, 22 mGNs in length, is confined within two hybridization sites: GAA signal at position 29 and Afa family signal at position 51 ( Fig.…”

“…FISH analysis of the reconstructed chromosomes resulting from this interchange allowed to attain significantly higher precision in the location of the translocation breakpoints compared to our previous studies with the parental lines (6,8). The putative breakpoints of the interchange were found to occur within the regions, 6 mGNs in length, located distally to the GAA hybridization site positioned in the long arm of chromosome 2H at 14 mGNs from the centromere, and at the segment confined within outer borders of the Afa family bands localized terminally in the long arm of chromosome 7H, at positions 49 and 61, respectively ( Fig.…”

“…The same materials were further subjected to karyotype analysis, including differential staining of chromosomes, to identify the position of the rearrangement breakpoints (8). Because most of the Giemsa bands were found to reside in the pericentromeric regions of the chromosomes, a number of rearrangement breakpoints which were localized distally to any marker bands escaped precise detection by this technique.…”

“…the multiple reconstructed barley karyotype PK 88-19 and the initial spring barley variety Freya (standard karyotype) were used as experimental materials in this study. PK 88-19 was selected (Gecheff, unpublished data) in the segregating progenies of a cross between reconstructed karyotypes PK-88 (6) and the structural mutant i-19 (8).…”