The present paper deals with the results of electron-microscopic observations on the hypertrophied hypocotyl of radish caused by an application of MCP (Sodium [(4-chloroo-tolyl) oxy] acetate).
Hypertrophied tissues were induced by the solution of MCP in the concentration 1.0 ppm. Short time treatment of MCP (less than 24 hrs) caused the malformation of the seedling even after their transplanting to the condition without the chemicals. When the radish seeds were treated in the lower concentration of MCP, they grew up as well as the control after their transplanting, but died from the treatment of MCP in higher concentration.
From histological observations on the hypertrophied hypocotyl, intercellular space was not recognized abundantly in the central cylinder compared with that of cortex tissues.
The cortical cell had a large vacuole and thin peripheral layer of protoplasm. Plasmolysis did not occured and the cell membrane was adjacent to the cell wall. Degenerated plastids were scarcely recognizable in the vacuole of cortical cells, and sometimes degenerated plastids and swelled mitochondria were observed in the cells of central cylinder. Abundant protoplasm, nuclei, proplastids and plasmodesmata as shown in the normal cells were observed in the primordium-cells of roots affected with the chemicals. Cotyledon was not injured with the application of MCP. Osmiophilic granules, grana structures and matrix were found in most chloroplasts of cotyledon cells.