Comparison of ribosomal DNA sites inLolium species by fluorescencein situ hybridization

The position of the 18S-5.8S-26S and 5S rRNA genes have been physically mapped on the chromosomes of sevenLolium taxa. 18S-5.8S-26S sites were seen on two pairs of chromosomes in the inbreeding taxa. In the outbreeding taxa six sites were found in theL. multiflorum, seven inL. perenne and nine inL. rigidum var.rigidum. Two 5S sites were found in each of the taxa. In the inbreeders, the 5S sites were found adjacent to the 18S-5.8S-26S sites on chromosome 2. InL. multiflorum andL. perenne the 5S sites were on the short arm of chromosome 3. However, inL. rigidum var.rigidum the 5S rDNA site was found in either of the two positions.accepted by J.S. (Pat) Heslop-Harrison