Scanning Microscopy


Ultrastructural effects of ionizing irradiation were investigated on the specific constituents of plant cells, primarily in fruits, with reference to mushroom cells and comparable data in the literature. In the cell wall the dissolution of the middle lamellae, probably due to radiation damage of pectin, and irregular thickenings were found. In the vacuole the quantity of inclusions changed, or unusual aggregations appeared, presumably in connection with altered phenolic biosynthesis . In chloroplasts the senescence was inhibited, and dedifferentiation occurred into agranal state. In amyloplasts starch hydrolysis was hind ere d. These platidial effects are considered as visible signs of inhibition of synthesis of proteases, the LHCII, or amylolytic enzymes, respectively. Some lines of evidence suggest that the target for irradiation was outside of the plastids in all these cases. Starch resynthesis was observed in apple epidermis as a synergistic effect of CaCl2 treatment and gamma irradiation. In this case presumably the sugar recycled from the vacuole into the plastids due to altered membrane permeabilities.

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