Ontogenetic Changes in DNA Content in Roots of the Water Fern Azolla filiculoides

The DNA content of the apical cell and various other cells in the roots of Azolla filiculoides was determined by two-wavelength cytospectrophotometry. DNA content decreased markedly with increasing age of the apical cell; there was a similar but less pronounced trend in the other cell populations studied. These findings suggest the possibility of DNA amplification in very young roots with rapidly dividing cells.