Abstract: 45S rDNA and 5S rDNA were mapped on the metaphase chromosomes of 3 diploid wild
rose species：Rosa multibracteata Helm. et Wils.，R. soulieana Crép. and R. laevigata Michx.，respectively，
by double color fluorescence in situ hybridization. The 45S rDNA chromosomal distribution patterns were
highly conserved among the three species. Each species had a pair of 45S rDNA loci on the short arms of
one pair of heteromorphic submetacentric homologous chromosomes. The 5S rDNA sites were different in
number and location among the three species. A pair of 5S rDNA signals was detected on the
chromosomes of R. multibracteata，and two pairs of 5S rDNA sites were detected on those of both R.
soulieana and R. laevigata. 5S rDNA were localized near the centromere region on the long arms of
chromosomes. The number，location and fluorescent intensity of the rDNA signals varied somewhat in
these three species. These results indicated that the double color FISH with 45S rDNA and 5S rDNA as
probes supplied some characteristic cytomolecular markers for identifying their own chromosomes for these species.

Key words: Rosa L., rDNA, fluorescence in situ hybridization（FISH）, karyotype