Nucleolus organiser variation in wheat and rye revealed by in situ hybridisation

Abstract

The technique of in situ hybridisation has been used to demonstrate that some wheat varieties have very different numbers of ribosomal RNA genes clustered in homologous nucleolus organisers. In these experiments the labelled probe was RNA synthesized in vitro using wheat ribosomal DNA cloned in a bacterial plasmid as template. Homologous nucleolus organisers were identified by the use of intervarietal chromosome substitution lines. A variety of rye has been shown to be heterozygous for the number of rRNA genes clustered in its major pair of nucleolus organisers. The in situ hybridisation technique has also been used to demonstrate an anomalous deletion of rDNA in an aneuploid derivative of Chinese Spring wheat.