Zeatin

About: Zeatin is a research topic. Over the lifetime, 2467 publications have been published within this topic receiving 64092 citations. The topic is also known as: Zeatin & (E/Z)-zeatin.

Cytokinin Structure-Activity Relationships and the Metabolism of N6-(Δ2-Isopentenyl)Adenosine-8-14C in Phaseolus Callus Tissues

Abstract: The activities of the free base and ribonucleoside forms of cytokinins bearing saturated and unsaturated N(6)-isoprenoid side chains have been examined in callus cultures derived from Phaseolus vulgaris cv. Great Northern, P. lunatus cv. Kingston, and the interspecific hybrid Great Northern x Kingston. In callus of cv. Great Northern, cytokinins bearing saturated side chains (N(6)-isopentyladenine, N(6)-isopentyladenosine, dihydrozeatin, and ribosyldihydrozeatin) were always more active than the corresponding unsaturated analogs (N(6)-[Delta(2)-isopentenyl]adenine, N(6)-[Delta(2)-isopentenyl]adenosine, zeatin, and ribosylzeatin). In callus of cv. Kinston, the cytokinins bearing unsaturated side chains were either more active or equally as active as the saturated compounds. These differences in cytokinin structure-activity relationships were correlated with differences in the metabolism of (14)C-N(6)-(Delta(2)-isopentenyl)adenosine. In Great Northern tissues, this cytokinin was rapidly degraded to adenosine; in Kingston tissues, the major metabolite was the corresponding nucleotide. The growth responses of callus of the interspecific hybrid were intermediate between the parental tissues, and the metabolism of (14)C-N(6)-(Delta(2)-isopentenyl)adenosine by the hybrid callus exhibited characteristics of both parental tissues. The results are consistent with the hypothesis that the weak activity of cytokinins with unsaturated side chains in promoting the growth of Great Northern callus is due to the rapid conversion of these cytokinins to inactive metabolites.

Effects of inoculum density, zeatin and sucrose on anthocyanin accumulation in a carrot suspension culture

Abstract: Anthocyanin formation in a suspension culture of Daucus carota is induced by transfer from medium containing 2,4-dichlorophenoxyacetic acid (2,4-D) to one lacking 2,4-D. The specific yields were strongly influenced by the inoculum density. Inoculum density altered the effect of zeatin concentration on anthocyanin accumulation. The in part by increasing the sucrose levels. It was inferred from the results that sucrose was exhausted at a low concentration of sucrose and at a high cell density, resulting in the decrease of yield of anthocyanin.

Cytokinin-induced ethylene biosynthesis in nonsenescing cotton leaves.

Abstract: The influence of cytokinins on ethylene production was examined using cotton leaf tissues. Treatment of intact cotton (Gossypium hirsutum L. cv LG 102) seedlings with both natural and synthetic cytokinins resulted in an increase in ethylene production by excised leaves. The effectiveness of the cytokinins tested was as follows: thidiazuron ≫ BA ≫ isopentyladenine ≥ zeatin ≫ kinetin. Using 100 micromolar thidiazuron (TDZ), an initial increase in ethylene production was observed 7 to 8 hours post-treatment, reached a maximum by 24 hours and then declined. Inhibitors of 1-aminocyclopropane-1-carboxylic acid (ACC) synthesis and its oxidation to ethylene reduced ethylene production 24 hours post-treatment; however, by 48 hours only inhibitors of ACC oxidation were effective. The increase in ethylene production was accompanied by a massive accumulation of ACC and its acid-labile conjugate. TDZ treatment resulted in a significant increase in the capacity of tissues to oxidize ACC to ethylene. Endogenous levels of methionine remained constant following TDZ treatment. It was concluded that the stimulation of ethylene production in cotton leaves following cytokinin treatment was the result of an increase in both the formation and oxidation of ACC.

Use of a cytokinin conjugate for efficient shoot regeneration from leaf sections of highbush blueberry

Abstract: Conditions for improving the efficiency of shoot regenration from leaf sections of highbush bluebeery (Vaccinium corymbosum L.) were investigated. Effectiveness of tissue culture medium supplemented with the cytokinin conjugate zeatin riboside or the cytokinin zeatin at 10, 20, or 30 μM was compared with medium supplemented with the optimum 2iP concentratioin of 15 μM. Use of 20 μM zeatin riboside resulted in the most shoots per leaf section, ≃6-fold higher than the number of shoots produced on 2iP medium. The number of shoots produced on medium supplemented with zeatin was not significantly higher than the number of shoots produced on 2iP medium []