Cytophotometrical measurement of nuclear DNA content in some coniferous and deciduous trees

The DNA content of nuclei from meristematic root tip cells of five coniferous and one deciduous tree species and, for comparison, ofVicia faba was cytophotometrically determined. The DNA values of diploid nuclei fromGinkgo biloba are approximately a quarter lower than those fromVicia faba. The nuclear DNA values of the other tree species are merely a third to a ninth part of those ofVicia faba. In three tree species, as well as diploid, we have found nuclei of different polyploid level.The reliability of different cytochemical methods, which are used for determination of the nuclear DNA content, is critically analyzed. The DNA values of the investigated tree species are discussed in connection with the evolution of the DNA content in higher plants.