Nuclear DNA and nucleotype effect

The meaning of C DNA amount for the organism, in this mainly retroelements constituting often over 50% of the genome, is surveyed. Content of nuclear DNA is of specific character but among plant species there occur some exceptions. There exists the variation among the biotypes of the same species on the score of this parameter. Genomes can vary in DNA amount even over 1000-fold in angiosperms. Some close related species vary even 30-fold on that score. In some cases less complex organisms posesses more DNA than high advanced ones. These cases were named the paradox C-value. There are different theories, which try to explain these fenomena.