Abstract
JENSEN1 has also claimed that the ability to plasmolyse in onion cells is not a reliable index to their viability, because he observed some abnormal cells in which vacuoles were normally stained by neutral red solution and tonoplasts still retained their permeability, having the cytoplasmic layers torn outside the tonoplasts. In a previous report3 I stated that such abnormal cells have not yet been observed during several years study in the parenchyma cells of the cortex in woody plants, but some parenchyma cells are found in which the ectoplasts still retain their semi-permeability though their tonoplasts are torn and their cytoplasmic layers are mixed with vacuolar content (see plate 1,2 ref. 2) However, such abnormal cells are easily distinguishable from the normal by their appearance. Thus, in the parenchyma cells in twigs of woody plants, unlike the case of onion cells, it may be possible to determine the relative degree of viability in parenchyma cells, upon the basis of both their vital staining with neutral red solution and the appearance of plasmolysed cells, at least in one and the same series of experiments. However, judging3 of the intactness of twig as a whole cannot be made only on the basis of plasmolysis test in parenchyma cells just subsequent to, or even after, many days of thawing, because inner cortex, pith ray, and pith periclinal tissue are less resistant to freezing than parenchyma cells of cortex. Accordingly, to demonstrate the intactness of a treated twig as a whole, it was planted in moist sand and its capacity tested to continue normal development at least for three months after planting, as mentioned in my reports4. Even in the tetrazolium5 test used by Parker, it may be said that judging the intactness in plants means only determination of a relative value of viability of certain tissues in twig or leaf without testing the whole of it as is done by the plasmolysis method.
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References
Jensen, A. B., Protoplasma, 36, 195 (1942).
Sakai, A., Low Temp. Sci., Ser. B., 17, 21 (1959).
Sakai, A., Low Temp. Sci., Ser. B., 13, 43 (1955).
Sakai, A., Low Temp. Sci., Ser. B., 14, 17 (1956).
Parker, J., Bot. Gaz., 121, 46 (1959).
Sakai, A., Nature, 183, 393 (1960).
Sakai, A. (unpublished work).
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SAKAI, A. Survival of Woody Plants at Extremely Low Temperatures. Nature 187, 1134 (1960). https://doi.org/10.1038/1871134a0
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DOI: https://doi.org/10.1038/1871134a0
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