LOCALIZATION OF RNA GENE SITES AND SECONDARY CONSTRICTIONS IN VICIA-NARBONENSIS AND VICIA-SATIVA

Sites of 18/25S RNA genes and those of secondary constrictions have been located in metaphase chromosomes of V. narbonensis and V. sativa by RNA/DNA in situ hybridization and Feulgen staining. In V. narbonensis the rRNA genes are located in median position on one pair of chromosomes, which is the shortest of all in the genome. In V. sativa rRNA genes are located in two pairs of chromosomes. The two heterologous sites differ markedly in the level of labeling. Strong labeling is found in a submedian position of a short pair of chromosomes. Weaker labeling is found in a median position on the longest pair of chromosomes. In V. narbonensis and V. sativa the position of the grain clusters correlate with the position of the secondary constrictions in chromosomes stained by Feulgen. The implications with respect to karyograms of V. narbonensis and V. sativa known from the literature are discussed. © 1979 Springer-Verlag.