The Effect of 2.4-Dichlorophenoxyacetic acid on the Staminal Hair Cells of Tradescantia in vivo
1. 24-D sodium hydrate effect on the mitotic cells
1953 Volume 66 Issue 779-780 Pages 155-160
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1953 Volume 66 Issue 779-780 Pages 155-160
By means of the agar plate method, the action of 2.4-dichlorophenoxyacetic acid sodium, hydrate (hereafter abbreviated 2.4-D)was investigated in the staminal hair cells of Tradescantia reflexa in vivo.
In the treatment with high concentrations (1-0.5%) of 2.4-D solution, the cells of staminal hairs become gelatinized within 25-60 minutes and later become sol state. Similar solidification of the cell contents would occur also in low concentrations (0.08-0.01%) of 2.4-D solution after survival for weeks and, the cell contents seem to be entirely liquefied. It may be thought that this phenomenon is due to the hydration of the protoplasm caused by the action of 2.4-D sodium salt.
In the concentrations of less than 0.1% of this drug, some of the hair cells become gelatinized and die in a few days after the treatment, however, during this lapse of days some of them aquire resistancy to the toxicity of the 2.4-D sodium salt and recover their vital forces. These cells then grow unusually containing fully grown plastids and survive a few weeks or more. In the cells with aquired resistancy to the 2.4-D, it is recognized that the cells can make use of this drug as a growth promoting hormone.
Any concentration of 2.4-D is effective on the mitosis and makes the chromosomes sticky. Consequently this drug can introduce chromosome aberrations, abnormal separation of anaphase chromosomes and secondarily the abnormalities of cell wall formation. Daughter cells with unequal size, micronuclei, imcomplete cell walls and binucleate cells appear in the 2.4-D treatment. Some of these mitotic abnormalities would appear also in the concentrations of 2.4-D solution, in which the resting nuclei can enter into the mitosis de novo.
It is considered that the specific actions of 2.4-D sodium salt on the mitotic cells may be responsible for its killing effect to the weeds and for the formation of abnormal tissues to the treated plants.
