CHIAS-based positioning of recombination hotspots and Giemsa bands in a multireconstructed barley karyotype

Abstract The chromosome complement of reconstructed barley karyotype PK 88 was analyzed by computer-aided Chromosome Image Analysis System (CHIAS). Fine mapping of Giemsa N-bands and regions with increased meiotic recombination activity along each individual chromosome was achieved. It was also found that CHIAS-visualized condensation profiles can be utilized as a reliable criterion for subtle differentiation of hetero- and euchromatin domains within a defined chromosomal regions. Application of CHIAS on karyotypes with distinct chromosome morphology was found to be an appropriate and reliable tool for screening of changes in chromatin compactness and its functional characteristics

Cytological and molecular evidence of deletion of ribosomal RNA genes in chromosome 6 of barley (Hordeum vulgare)

The barley chromosomal mutant T-35, in which only one pair of satellite chromosomes is apparent, was analyzed using a range of cytological and molecular techniques. Using conventional Feulgen staining, Giemsa and silver banding, in situ hybridization, and Southern blot analysis, unequivocal cytological and molecular evidence was obtained that T-35 is a homozygous deletion of rRNA genes residing in the nucleolus organizer region (NOR) of chromosome 6. According to the criteria of arm ratio and Giemsa-banding pattern of this chromosome, the deletion involved the whole NOR, one of the breakpoints being localized in the short arm proximally to the NOR-associated heterochromatic band, the other probably in the satellite of the chromosome. As a result of this deletion, an increased activity of the rRNA genes (as indicated by the size of the silver bands) on the other NOR-bearing chromosome (chromosome 7) was observed. The possible reasons for this phenomenon are discussed

CALLUS INDUCTION AND PLANT REGENERATION FROM BARLEY MATURE EMBRYOS (HORDEM VULGARE L.)

ABSTRACT Immature and mature embryos of four Bulgarian winter and spring barley (Hordem vulgare L.) (72.2% and 97.8%, respectively) and the highest number of regenerated plants per embryo (9.3 and 13.3, respectively). A comparison of the responses of the two types of explants indicated that the mature embryos were more useful explants for plant regeneration, and therefore, being available throughout the year, can be used as an effective explant source in barley studies

DNA methylation pattern in a barley reconstructed karyotype with deleted ribosomal gene cluster of chromosome 6H

A reconstructed barley karyotype (T-35) was utilised to study the influence of chromosomal rearrangements on the DNA methylation pattern at chromosome level. Data obtained were also compared with the distribution of Giemsa N-bands and high gene density regions along the individual chromosomes that have been previously described. In comparison to the control karyotype (T- 1586), the DNA methylation pattern was found to vary not only in the reconstructed chromosomes but also in the other chromosomes of the complement. Significant remodelling process of methylation pattern was found also in the residual nucleolus organiser regions (NOR) on chromosome 5H as a consequence of deletion comprising the whole NOR of chromosome 6H in T-35. Moreover, differences between corresponding segments of the homologues with respect to some other chromosome locations were also observed. Repositioning of genomic DNA methylation along the metaphase chromosomes following chromosomal reconstruction in barley seems to be essential to ensure correct chromatin organisation and function

DNA methylation and chromosomal rearrangements in reconstructed karyotypes of Hordeum vulgare L

One standard and two reconstructed barley karyotypes were used to study the influence of chromosomal rearrangements on the distribution pattern of DNA methylation detectable at the chromosome level. Data obtained were also compared with Giemsa N-bands and high gene density regions that had been previously described. The effect of chromosomal reconstruction in barley seems to be decidedly prominent in the repositioning of genomic DNA methylation along metaphase chromosomes. In comparison to the standard karyotype, the DNA methylation pattern was found to vary not only in the reconstructed chromosomes but also in the other chromosomes of the complements not subjected to structural alterations. Moreover, differences may occur between corresponding regions of homologues. Some specific chromosomal bands, including the nucleolus-organizing regions, showed a relative constancy in the methylation pattern, but this was not the case when the two satellites were combined by translocation in chromosome 6H5H of line T-30. Our results suggest that epigenetic changes like DNA methylation may play an important role in the overall genome reorganization following chromosome reconstructio