Poster: Root Biology
Abs #
523: Comparative Sensitivity to Chemical Stress of the Plerom and Periblem Cell Files of Root Meristem
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Presenter: |
Litinskaya, Tatiana K., litat16@yahoo.com |
Authors | Litinskaya, Tatiana K. (A) | | Affiliations: |
(A): Timiryazev's Institute of Plant Physiology, RAS, ASPB member ID # 62785
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In the normal root meristem of 3-6-day-old maize (Zea mays L., cv Sterling) seedlings grown in darkness at 27C the number of cells in periblem files declined as follows: endoderm > inner cortex > rhizoderm > pericycle > outer cortex > hypoderm. On the 1st day there was 180 cells in endoderm and 135 cells in hypoderm, 143 and 118 cells on the 2nd day, and 100 and 82 on the 3rd day. Mitotic index (MI) value in each of the periblem tissues was proportional to the number of cells in the file. MI decreased from 12-15% to 7-9% in the same sequence of tissues. The pattern of divisions was similar in all tissues: MI increased along the first 20-40 cells in the file, then decreased in the middle of meristem, increased again in the second part of meristem during the last mitotic cycle (MC), and finally dropped to zero in the last 20-30 cells of the file. In plerom the number of cells in files of axial parenchyma was two times less than number of cells in periblem. Their MI was 5-9%, and the only peak of mitotic activity was observed between 10th and 30th cells of file. Volume of cells of axial parenchyma was the same as of cortex cells, while length of most distant dividing cells reached 30m (i.e. 3 times longer than cortex cells), and density of cytoplasm was 40% lower. This phenomenon indicates that plerom files have one MC less than periblem files. Under chemical stressors (Cd, metabolic inhibitors) the number of cells in the files of periblem tissues was reduced because of absence of the last MC. Furthermore, a gradient of sensitivity was observed: outer periblem files were injured more than inner ones. Plerom cell files were injured lesser then periblem files. The data shows mechanism of cellular resistance of plerom tissues.
