Molecular Cytogenetic Localization and Characterization of 5S and 25S rDNA Loci for Chromosome Identification in Oilseed Rape (Brassica napus L.)

Chromosome identification in oilseed rape (Brassica napus L.)is extremely difficult using conventional cytogenetic techniquesbecause amphidiploid Brassica species possess numerous verysmall chromosomes with few cytogenetic landmarks. In combinationwith methods for improved chromosome preparations, we used asimplified fluorescencein situ hybridization (FISH) techniqueto localize simultaneously the gene families coding for 5S and25S rDNA in B. napus. The resulting hybridization patterns enabledten of the 19 oilseed rape chromosome pairs to be unequivocallyidentified. Copyright 2000 Annals of Botany Company Brassica napus, oilseed rape, rDNA, molecular cytogenetics, FISH, chromosome identification