The Ribosomal RNA Gene Number and the Length of the Nucleolar Secondary Constrictions in Bellevalia Romana and B. Dubia (Liliaceae): A Possible Correlation

Karyological analyses and rRNA/DNA hybridization experiments were carried out in Bellevalia romana and B. dubia (Liliaceae). B. romana (2 n=8) has four short NORs and 3,200 genes for ribosomal RNA; B. dubia (2 n=8) has six NORs clearly longer than those of B. romana and 9,800 rRNA genes. The gene numbers are calculated on the basis that both species possess 24 × 10 −12 g/2C nucleus. A correlation between cytological and molecular hybridization results is made.