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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.


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Journal ArticleDOI
TL;DR: It is concluded that the culture of seeds on cytokinin-containing media, followed by transfer to cytokinIn-free medium, is a suitable procedure for rapid production of a large number of uniform regenerants.
Abstract: We determined the effects of zeatin (ZEA), isopentenyl adenine (2iP), kinetin (KIN), benzyladenine (BA), and thidiazuron (TDZ) on seed germination, elongation of seedling shoots and roots, frequency of regeneration, and the number of regenerants per seedling in Lotus corniculatus L. Sterilized seeds were cultured in vitro on Murashige and Skoog (1962) medium containing 3% sucrose, 0.7% agar, and various cytokinins (0, 0.08, 0.22, 0.35, 0.80, 2.20, and 3.50 μM). After 30 days, seedlings were transferred to cytokinin-free medium for another 60 days. All cytokinins stimulated the rate and percentage of seed germination at least twofold in optimum concentrations; TDZ and ZEA were the most active, followed closely by BA, whereas KIN and 2iP stimulated germination in higher concentrations only. Elongation of shoots and roots was strongly inhibited at the lowest TDZ and BA concentrations, whereas ZEA, KIN, and 2iP exerted moderate, dose-dependent inhibition. The frequency of regenerant-producing seeds was highest on ZEA and BA, whereas the greatest number of regenerants per seedling was found on TDZ. It is concluded that the culture of seeds on cytokinin-containing media, followed by transfer to cytokinin-free medium, is a suitable procedure for rapid production of a large number of uniform regenerants. The presumed role of particular cytokinins is discussed.

81 citations

Journal ArticleDOI
TL;DR: It is suggested that conjugated zeatin is an important form of cytokinin during the ripening stage of rice, because the level of each of the cytokinins in Akenohoshi was higher than that in Nipponbare.
Abstract: Changes in exudation rate and cytokinin activities in the exudates were measured in two varieties of rice (Oryza sativa L.), cv Nipponbare (a Japanese normal cultivar) and cv Akenohoshi (a high-yielding cultivar). The exudation rates of Akenohoshi, the leaves of which remained green for a longer time, were higher than those of Nipponbare after the booting stage. Cytokinin activities in the exudates of Akenohoshi were higher than those of Nipponbare during the ripening period. Cytokinins in the exudates collected during the middle of the ripening stage were analyzed with mass spectrometry using deuterium-labeled standards. trans-Zeatin, trans-ribosylzeatin, and N6-isopentenyladenosine were detected as free cytokinins, and zeatin was detected in the hydrolysates of highly polar fractions (“conjugated zeatin”) in the exudates of both cultivars. Conjugated zeatin was the predominant cytokinin in both cultivars. Therefore, we suggest that conjugated zeatin is an important form of cytokinin during the ripening stage. The level of each of the cytokinins in Akenohoshi was higher than that in Nipponbare. Also, we discuss the correlation between the leaf senescence and cytokinin content in root exudates.

81 citations

Journal ArticleDOI
TL;DR: The identities and concentrations of cytokinins in goldenrod ball galls, normal goldenrod stems, and in the gall-forming larvae of the tephritid fly Eurosta solidaginis were determined in order to gain insight into the mechanism of ball gall formation on Solidago altissima.
Abstract: ummary • The identities and concentrations of cytokinins in goldenrod ball galls, normal goldenrod stems, and in the gall-forming larvae of the tephritid fly Eurosta solidaginis were determined in order to gain insight into the mechanism of ball gall formation on Solidago altissima. • Zeatin, zeatin riboside, isopentenyladenine, and isopentenyladenosine were identified and quantified by gas chromatography–mass spectrometry in ball galls, goldenrod stems, and in larvae of E. solidaginis. • Concentrations of the four cytokinins were higher in gall tissues than in stem tissues when expressed on a weight per stem length basis but not when expressed on a weight per weight basis. Isopentenyladenine was the most abundant cytokinin in larvae from developing galls and in larvae from fully formed galls exhibiting ‘green islands’. In first instar larvae, isopentenyladenine was present at a much higher concentration (c. 50 fold) than in control stem tissues. • The presence of an E. solidaginis larva results in higher cytokinin amounts in a given length of stem than are found in its absence. Larvae of E. solidaginis may act as point sources of isopentenyladenine in developing ball galls. Abbreviations BHT, butylated hydroxytoluene; DMSO, dimethylsulphoxide; DMSO−, dimethylsulphoxide anion; GC-MS, gas chromatography mass spectrometry; HPLC, high pressure liquid chromatography; iP, isopentenyladenine; iPA, isopentenyladenosine; Me-dHZ, methyl-dihydrozeatin; Me-dHZR, methyl-dihydrozeatin riboside; Me-iP, methyl-isopentenyladenine; Me-iPA, methyl-isopentenyladenosine; Me-Z, methyl-zeatin; Me-ZOG, methyl-zeatin-O-glucoside; Me-ZR, methyl-zeatin riboside; Me-ZROG, methyl-zeatin riboside-O-glucoside; m/z, mass to charge ratio; PVPP, polyvinylpolypyrrolidone; SIM, selected ion monitoring; TEAB, triethylammonium bicarbonate; Z, zeatin; ZR, zeatin riboside.

81 citations

Journal ArticleDOI
TL;DR: The results suggest that, at least in oat and possibly in wheat, zeatin-type bases, ribosides and O-glucosides supplied to the leaf in xylem sap are likely to play a role in regulating transpiration in vivo.
Abstract: This study was conducted lo determine whether naturally occurring xylem cytokinins, when supplied to leaves via the xylem at approximately endogenous concentrations, increase transpiration and delay senescence in selected monocot species (oat and wheat). The concentrations of some of the major cytokinins (zeatin, dihydrozeatin, ciszeatin and their ribosides, the O-glucosides and nucleotides) were determined in the xylem exudate of oat and wheat seedlings by radioimmunoassay. Evidence is presented that the small volume of exudate (4–5 mm3) collected per plant was xylem sap in transit at the time of shoot excision. Using the data on cytokinin levels, the individual bases and ribosides (and a base/riboside mixture), at multiples of concentrations determined in xylem sap, were tested in transpiration and senescence bioassays. The individual O-glucosides (and mixtures of the O-glucosides) were similarly tested at (i) multiples of the molar concentrations of the corresponding bases and ribosides, and/or at (ii) multiples of the endogenous concentrations. Similarly, zeatin and dihydrozeatin nucleotides were tested at multiples of the molar concentration of zeatin riboside and, in some instances, at multiples of endogenous concentrations. Our results suggest that, at least in oat and possibly in wheat, zeatin-type bases, ribosides and O-glucosides supplied to the leaf in xylem sap are likely to play a role in regulating transpiration in vivo. O-glucosides in oat xylem sap may be important regulators of leaf senescence in the intact plant. The nucleotides were present in xylem sap at lower concentrations than most of the bases, ribosides and O-glucosides. The nucleotides appear likely to play a lesser role than the bases, riboside and O-glucosidcs in controlling transpiration and senescence in the intact plant.

80 citations

Journal ArticleDOI
TL;DR: To determine the utility of zeatin for initiation of diverse genotypes, 96 Vaccinium accessions from the National Clonal Germplasm Repository, representing 22 species and 44 cultivars, were screened using 25C and low light intensity.
Abstract: Explants of mature pot-grown Vaccinium corybosum L. cultivars were tested for initiation of new shoots using two growing conditions and four cytokinin treatments. Initiation tests with 12 genotypes showed significantly higher rates of new shoot growth on modified woody plant (MWPM) medium with 4 mg zeatin/liter at 25C under low light intensity than on any other treatment. Explants at 25C in light with 10 or 15 mg 2iP/liter initiated at a moderate rate, but significantly lower rates were found for all controls and at 4C in darkness. To determine the utility of zeatin for initiation of diverse genotypes, 96 Vaccinium accessions from the National Clonal Germplasm Repository, representing 22 species and 44 cultivars, were screened using 25C and low light intensity. Initiation rates higher than 60% were achieved for 89 of 96 accessions tested. Chemical name used: N6-(2-isopenteny1) adenine (2iP), 6-(4-hy- droxy-3-methylbut-2-eny1amino)purine (zeatin).

80 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202333
2022103
202135
202034
201932
201848