Kinetin

About: Kinetin is a research topic. Over the lifetime, 7856 publications have been published within this topic receiving 135550 citations. The topic is also known as: Kinetin.

Mechanism of a Synergistic Effect of Kinetin on Auxin-induced Ethylene Production: Suppression of Auxin Conjugation

Abstract: In hypocotyl segments of mung bean (Phaseolus mungo L.) seedlings, exogenously supplied indoleacetic acid was rapidly conjugated mainly into indoleacetylaspartic acid, which was inactive in inducing ethylene production. Kinetin is known to stimulate indoleacetic acid-induced ethylene production. The mechanism of kinetin action on indoleacetic acid-induced ethylene production by hypocotyl segments of mung bean seedlings was studied in relation to indoleacetic acid uptake and indoleacetic acid metabolism. Kinetin enhanced indoleacetic acid uptake during the initial 2-hour incubation and markedly suppressed the conversion of indoleacetic acid to indoleacetic acid conjugates throughout the whole 7-hour incubation. As a result, there was more free indoleacetic acid and less conjugated indoleacetic acid in the segments treated with kinetin than in those receiving no kinetin. A close relationship was demonstrated between the rate of ethylene production and the level of free indoleacetic acid, which was regulated by kinetin.

In vitro propagation of Saussurea obvallata (DC.) Edgew.—an endangered ethnoreligious medicinal herb of Himalaya

Abstract: This is the first report of a micropropagation protocol for Saussurea obvallata (DC.) Edgew. (Asteraceae), a rare, threatened and near-endemic medicinal herb of the Indian Himalayan region. Multiple shoots were formed from epicotyle explants on Murashige and Skoog (MS) medium supplemented with 1.0 µM kinetin and 0.25 µM α-naphthaleneacetic acid. A maximum of five shoots were obtained from one explant in a 75-day culture period. The effect of subsequent subcultures on shoot formation was also studied. After 100% in vitro rooting was obtained in half-strength MS supplemented with 2.5 µM Indole-3-butyric acid, the plantlets were transferred to ex vitro conditions. Following a 15-day in vitro rooting period and 12 days of ex vitro acclimatization, 66.7% of the plantlets had established in the field. Application of this protocol has the potential to substantially reduce the pressure on natural populations

Factors regulating ethylene biosynthesis in etiolated Arabidopsis thaliana seedlings

Abstract: ethylene in other plant tissues. Auxin, cytokinin, brassinosteroid and cupric ion were found to highly elevate ethylene show that the synergism between cytokinin and auxin in production in these seedlings, but several other signaling com- Arabidopsis is due to an enhancement of the effects of auxin, pounds, as well as wounding and mechanical stimulation, had but not by increased elevation of ACS4 mRNA levels. These little or no effect. A mutant that disrupts the ACS5 gene results suggest that cytokinin acts post-transcriptionally to (cin5) was partially defective in the induction of ethylene in increase ACS4 function, which, coupled with the observation that auxin elevates ACS4 mRNA levels, accounts for the the presence of brassinosteroids, suggesting a role for this synergistic interaction. isoform in mediating this response. Cytokinin displayed a synergistic interaction with both brassinosteroid and auxin,

Antagonisms between Kinetin and Amino Acids: Experiments on the Mode of Action of Cytokinins.

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.