Chromosomal locations of four minor rDNA loci and a marker microsatellite sequence in barley

Abstract

Four minor rDNA loci have been mapped physically to barley (Hordeum vulgare L.) chromosomes 1 (7l), 2 (2l), 4 (4l), and 5 (1l) by a two-step in situ hybridization procedure including a GAA microsatellite sequence. Reprobing with the microsatellite resulted in a distinct banding pattern, resembling the C-banding pattern, which enabled unequivocal chromosome identification. This study suggests that gene mapping accuracy may be improved by using probes with well-characterized and narrow hybridization sites as cytological markers which are situated close to the gene locus. One of the rDNA loci is located about 54% out on the short arm of chromosome 4 and it has not previously been reported in barley. We have designated the new locus Nor-l6. rDNA loci on homoeologous group 4 chromosomes have not yet been reported in other Triticeae species. The origin of these 4 minor rDNA loci is discussed in relation to their equilocal distribution on the chromosomes.

Hordeum vulgare × H. bulbosumtetraploid hybrid provides useful agronomic introgression lines for breeders

“…H. vulgare chiomosoines were identified using fluorescent in situ hybridisation (FISH) (Fig. 1A) (Pedersen & Linde-Laursen 1994). To establish which of the H. vulgare chromosomes contained an introgression from H. bulbosum, the same chromosome preparations were then re-probed following removal of the labelled DNA and subjected to genomic in situ hybridisation (GISH).…”

Physical Mapping of Ribosomal DNA Genes on <i>Jatropha curcas</i> Chromosomes by Multicolor FISH

“…Tandem repeat sequences include several types of repeat sequences, such as satellite DNA, 2 kinds of ribosomal RNA genes, (rDNA)-45S and 5S rDNA, and telomeric repeats (Lapitan 1992). rDNA belongs to a highly conserved repeat sequence family with hundreds of copies and locates on 1 or more pairs of chromosomes (Pedersen and Linde-Laursen 1994). Tandemly repeated sequences are also excellent cytological markers for karyotyping, especially in species with small chromosomes (Hasterok et al 2001).…”

A Transgenomic Cytogenetic Sorghum (Sorghum propinquum) Bacterial Artificial Chromosome Fluorescencein SituHybridization Map of Maize (Zea maysL.) Pachytene Chromosome 9, Evidence for Regions of Genome Hyperexpansion

“…The mitotic chromosomes are easier to prepare, but meiotic chromosomes have the advantage of longer axial fibers for improved localization within chromosome arms (Pedersen and Linde-Laursen 1994;Cheng et al 2001a,b;Desel et al 2001;Kulikova et al 2001). Another advantage of meiotic chromosomes is that the pachytene-based cytogenetic maps can be compared to and integrated directly with recombination nodule-based maps and translocation breakpoint data (Anderson et al 2004;Sheridan and Auger 2006).…”