PHYLOGENETIC COMPARISON OF LARGE NUCLEAR DNA CONTENTS OF DIFFERENTIATED CELLS IN THE ROOTS OF EQUISETUM,TRADESCANTIA, AND HORDEUM

Nuclear DNA of meristematic, epidermal and root cap cells from the roots of three vascular plants—the cryptogam, Equisetum hyemale L, and the phanerogams, Tradescantia Clone 02 and Hordeum vulgare L.—was measured with quantitative Feulgen microspectrophotometry. Epidermal cells of all three species and root cap cells in both phanerogams contained up to 8fold the amount of nuclear DNA found in their respective meristematic telophase nuclei. In general, the large amounts of nuclear DNA parallel development and differentiation in the epidermis regardless of phylogeny, habitat, or degree of domestication. However, comparisons of the increase in nuclear DNA contents in the various epidermal cell types among these three species suggest that the mechanisms giving rise to these increases may differ phylogenetically and may represent another character in which cryptogams and phanerogams diverged in their evolution.