ISSN:
1432-2242
Keywords:
Wheat
;
Ribosomal RNA genes
;
Synthetic tetraploids
;
Evolution
;
Nucleolar activity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary The ribosomal RNA genes in the A genome of tetraploid (AABB) wheats are either absent or present at low levels. In four synthetic AABB tetraploids tested by in situ hybridization with a radioactive probe, the level of radioactive label at A and B NOR's corresponded to those of the parent species. There was no reduction after ten generations. In addition, the A chromosome rDNA is transcriptively active, the numbers of nucleoli being governed by the number of rRNA gene repeats in the smaller of the two A-genome NOR's. Since the wild tetraploid Triticum dicoccoides, as well as its domesticated derivatives, lack A-genome NOR's, their deletion is likely to have occurred prior to domestication, i.e. more than 10,000 years ago.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00249154
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