Antagonisms between Kinetin and Amino Acids: Experiments on the Mode of Action of Cytokinins.
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In this article, the maintenance of chlorophyll in darkened first leaves of oats was used as a bioassay for cytokinins in pea (Pisum sativum) roots.Abstract:
The maintenance of chlorophyll in darkened first leaves of oats was used as a bioassay for cytokinins in pea (Pisum sativum) roots. No cytokinin was found (in contrast with earlier reports on sunflower roots); however, the extracts contained two or more substances antagonistic to cytokinin, i. e., promoting the yellowing in this test. Because the most active of these appeared to be an amino acid, individual amino acids were examined for their ability to modify the greening reaction. As a result, l-serine was found to have these properties. It promotes yellowing whether the greening agent is kinetin, indoleacetic acid, or adenine; it is, therefore, not functioning as a specific cytokinin antagonist. Its action is due to promoting proteolysis. Its d-isomer is inactive. l-Arginine, which alone does not cause chlorophyll retention and only weakly inhibits proteolysis, strongly antagonizes the action of l-serine, and thus prevents the yellowing; this effect is specific, and the only other effective serine antagonist found, although much weaker, is l-threonine. The action of arginine is not due to its preventing serine uptake, but rather the action parallels the serine-arginine antagonism previously described for nitrate reductase induction. A novel interpretation of the effect of amino acids on this process is therefore put forward. In studies of the RNase in darkened oat leaves, serine was found to have no effect; however, kinetin strongly inhibits the normal rise in the level of RNase which occurs in the isolated leaf. Kinetin also maintains the integrity of the cell membranes. A variety of evidence leads to the conclusion that the primary action of kinetin on the leaf is to inhibit proteolysis, rather than to promote protein synthesis.read more
Citations
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References
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Journal ArticleDOI
Kinetin-like activity in root apices of sunflower plants.
Chanan Weiss,Yoash Vaadia +1 more
Journal ArticleDOI
The nuclease activity of bacillus subtilis
TL;DR: Activity so defined was shown by a variety of microorganisms, such as yeast, Penicillium qlaucum, and Asperqillus niqer, and by Bacillus coli, Bacillus proteus, and staphylococcus and it is apparent that these ester bonds may be broken without the separation of phosphoric acid from any of the four nucleotides.
Journal ArticleDOI
Amino acids as sources of nitrogen for the growth of isolated oat embryos
TL;DR: Brown as mentioned in this paper reported that ammonium sulphate, aspartic acid, glutamic acid, potassium nitrate and asparagine, at concentrations supplying equivalent quantities of nitrogen, showed progressive increases in their capacity to increase the dry weight and nitrogen content of barley embryos cultured for a period of one week.
Journal ArticleDOI
Increase in chromatin associated nuclease activity of excised barley leaves during senescence and its suppression by kinetin
TL;DR: No significant changes in the composition of chromatin were found when the excised barley leaves were floated on water or on kinetin solution in the dark, but increases in the activities ofchromatin associated ribonuclease and deoxyribonucleasing in leaves floated onWater drastically suppressed the increases in these enzymes.
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