| 英文摘要 |
Four-day old etiolated seed lings were sprayed with 2.5 x 10-3M 2, 4-D (pH 6.0) for 24 hr (treated seedlings) and the morphological. anatomical and biochemical changes were examined. The elongation of cells in the young meristematic region and in the early stages of differentiation were inhibited. The radial enlargement of the mature epicotyl was due to the increase in diameter of cortical and pith cells. The 2, 4-D treatment not only altered the size of the cells in the cortex and pith. but also increased the size of the nucleolus, especially in the cortex and vascular strands. The diameter of nucleolus was increased by 40% to 60% (1. 5-2.2 µm to 2.2-3.6 µm), but the size of nuclei was only slighly increased by the auxin treatment. The increase in diameter of nucleoli up to 6-8 µm observed previously by the auxin treatment in isolated nuclei was not found in situ in these cross sections. From these studies, the enlargement of nucleoli by auxin treatment was not found to be localized in any particular region and the nuclei with enlarged nucleoli isolated from the treated seedlings for in vitro studies were not preferentially obtained from any particular region of the tissue. |
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