Chromosomal distribution of 18S-25S rDNA in four Lupinus species visualized by fluorescence in situ hybridization.

The number and position of 18S-25S rDNA sites in 4 selected Lupinus species are reported for the first time. L. atlanticus, L. subcarnosus and L. paniculatus had two rDNA loci, while L. albus exhibited only one loci. Among these 4 species, all of them exhibited one large pair of strong signals that extends from the short arm to a NOR on a chromosome satellite. L. atlanticus, L. subcarnosus, L. paniculatus had one more locus of 18-25S rDNA, but a pair of weak hybridization signals were observed in L. paniculatus when 18S-25S rDNA was used as probe. The results are discussed in terms of the evolutionary relationships among these species.