Cytology of Vicia species. IX. Nuclear DNA amount, chromatin organization and computer aided karyotyping of a Russian accession of Vicia faba L

The Faba section of the Vicia genus, which includes several widely distributed species in Mediterranean countries is considered the most evolved. Indeed, it is known nuclear DNA values range from 9.15 pg. (2C value) in Vicia bithynica, to 26.56 pg. (2C value) in Vicia faba which has the highest DNA content in the genus. Banding pattern of metaphase chromosomes and nuclear DNA content in root meristematic cells of a Russian accession of V. faba were determined. Microdensitometric evaluation of nuclear absorption at different thresholds of optical density after Feulgen reaction indicated the organisation of the chromatin interphase nuclei. Karyotype, morphometric data and density distribution along the mid-rib of a chromatid were employed for the construction of a quantitative chromosome map generated by an automated image analysis system. The classification of Stebbins (1971), the TF% values (HUZIWARA 1962) and Rec. and Syi indices (GREILHUBER and SPETA 1976) were used to perform the analysis. The results are compared with previous data concerning V. faba