COMPARISON OF RIBOSOMAL DNA SITES IN LOLIUM SPECIES BY FLUORESCENCE IN-SITU HYBRIDIZATION

The position of the 18S-5.8S-26S and 5S rRNA genes have been physicall y mapped on the chromosomes of seven Lolium taxa, 18S-5.8S-26S sites w ere seen on two pairs of chromosomes in the inbreeding taxa, In the ou tbreeding taxa six sites were found in the L. multiflorum, seven in L. perenne and nine in L. rigidum var, rigidum. Two 5S sites were found in each of the taxa. In the inbreeders, the 5S sites were found adjace nt to the 18S-5.8S-26S sites on chromosome 2. In L. multiflorum and L. perenne the 5S sites were on the short: arm of chromosome 3. However, in L. rigidum var. rigidum the 5S rDNA site was found in either of th e two positions.