Chromosomal locations of four minor rDNA loci and a marker microsatellite sequence in barley.
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.
Pedersen
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C
Environmental Science and Technology Department, Risø National Laboratory, Roskilde, Denmark.
Linde-Laursen
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I
D002874:Chromosome Mapping / Q000379:methods; D004275:DNA, Ribosomal / Q000235:genetics*; D004276:DNA, Satellite / Q000235:genetics*; D005819:Genetic Markers; D001467:Hordeum / Q000648:ultrastructure*; D017404:In Situ Hybridization, Fluorescence; D012335:RNA, Ribosomal / Q000235:genetics*; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid
D004275:DNA, Ribosomal; D004276:DNA, Satellite; D005819:Genetic Markers; D012335:RNA, Ribosomal; D012337:RNA, Ribosomal, 18S; C065096:RNA, ribosomal, 26S