| Abstract: | The genus Phaseolus is characterized by a highly stable karyotype of 2n = 22. Despite this constancy, the size of the chromosomes varies, and crossing of species is possible only in a few cases. We determined the 2C nuclear DNA content of a number of Phaseolus species, cultivars and genotypes by flow cytometry, in order to realize the interspecific and intraspecific variation of the 2C value. The data range from 1.03 pg to 2.18 pg without any clear correlation to systematic relationships. The mean DNA values of wild and cultivated forms, as well as those of Andean and Mesoamerican genotypes, do not differ significantly. The variation is interpreted in terms of some nucleotypic adaptations. The data may be useful for molecular biological analyses, as well as for biotechnological and classical breeding programmes. |
