XVI International Botanical Congess
We have analyzed morphology of PCD using light, epifluorescence and transmission electron microscopy (TEM) in three cell lines in the roots of Azolla: a) tracheary elements (Tes), b) root cap cells and c) sieve elements (SEs). In addition we have triggered PCD following the application cadmium ions and probe cells for the animal apoptopic protein machinery: p53. TE cell elongation and secondary wall deposition is associated with the marginalization, condensation of chromatin in the nucleus and the formation of the compound vesicles, containing various cellular components. However, here unlike in TEs, SEs do not die: the cytoplasm remains alive at maturity and their nuclei became lobed, degenerate and pycnotic. Nuclear fragmentation also occurs in root cap cells. Our data indicate i) high concentrations of cadmium caused necrosis while ii) lower doses induced retardation of growth and development iii) appearance of cells with morphological characters that closely mirror those associated with apoptosis iv) overexpression of p53. Dr. Tatyana Kalynyak