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GrainGenes Reference Report: GEN-140-1367

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Reference
GEN-140-1367
Title
Ribosomal RNA multigene loci: nomads of the Triticeae genomes.
Journal
Genetics
Year
1995
Volume
140
Pages
1367-1377
Author
Dubcovsky J
Dvorak J
Abstract
The nucleolus organizing regions (NORs) on the short arms of chromosomes 1A^m^ and 5A^m^ of diploid wheat, Triticum monococcum L., are at the most distal loci in the linkage maps of these two chromosome arms. This distal location differs from the interstitial location of the Nor loci on chromosome arms 1BS of tetraploid Triticum turgidum L. and hexaploid T. aestivum L., 5DS of T. aestivum and diploid Ae. tauschii Coss., and 5HS of barley. Moreover, the barley 5HS locus is at a different location than the 5DS locus. However, other markers, including the centromeres, are colinear. These findings showed that the major Nor loci have repeatedly changed position in the chromosome arms during the radiation of species in the tribe Triticeae without rearrangements of the linkage groups. It is suggested that Nor loci may change position via dispersion of minor loci, that are shown here to exist in the T. monococcum genome, magnification of gene copy numbers in these minor loci, and subsequent deletion of the original major loci. Implications of these finding for the use of rRNA nucleotide sequences in phylogenetic reconstructions are pointed out.
Map Data
1AS, T.m. G3116 x DV92
[ Show all 8 ]
Image
XNor location on group 1 chromosomes
XNor location on group 5 chromosomes