Showing papers on "Zeatin published in 1981"
TL;DR: The similarity between anthocyanin synthesis and embryogenesis was observed in the time course as well as in the effects of growth regulators and the correlation between metabolic and morphological differentiation is discussed.
Abstract: A system in which anthocyanin synthesis could be induced under a defined condition, was established in a carrot suspension culture. A cell suspension culture of carrot (Daucus carota L. cv. Kurodagosun) was subcultured for more than a year in a medium containing 5 × 10−7M 2,4-dichlorophenoxyacetic acid (2,4-D). At every subculture the cultures were sieved through nylon screens and the cells and cell clusters collected in the size range of 31–81 μm were transferred to a fresh medium. When the cells were transferred to a medium without auxin, synthesis of anthocyanin was induced. Zeatin promoted anthocyanin synthesis in a medium lacking auxin, with maximum yields of anthocyanin obtained at 10−7 to 10−8M zeatin, 2,4-D at higher concentrations than 10−7M inhibited anthocyanin synthesis completely. The sieved cells were fractionated by Ficoll density gradient centrifugation. Somatic embryos were formed in the fraction of higher density (>14% of Ficoll) in a medium containing 10−7M zeatin but lacking auxin, while synthesis of anthocyanin was hardly observed. On the other hand, cells in the fraction of lower density (<12% of Ficoll) synthesized anthocyanin in the same medium, but formed few embryos. Forty to fifty percent of the total cells in this lighter cell fraction synthesized anthocyanin at a maximum. The similarity between anthocyanin synthesis and embryogenesis was observed in the time course as well as in the effects of growth regulators. The correlation between metabolic and morphological differentiation is discussed.
110 citations
TL;DR: The major cytokinins in stems of decapitated, disbudded bean plants have been identified by enzymic degradation, Sephadex LH20 and reversed phase high performance liquid chromatography, and by combined gas chromatography-mass spectrometry as zeatin ribotide-O-β-D-glucoside and dihydrozeatin ribotide.
Abstract: The major cytokinins in stems of decapitated, disbudded bean plants have been identified by enzymic degradation, Sephadex LH20 and reversed phase high performance liquid chromatography, and by combined gas chromatography-mass spectrometry as 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9-β-D-ribofuranosylpurine (zeatin riboside), 6-(4-hydroxy-3-methylbutylamino)-9-β-D-ribofuranosylpurine (dihydrozeatin riboside), and the 5′-phosphates of these compounds (zeatin ribotide and dihydrozeatin ribotide). Minor cytokinins in this tissue were tentatively identified as dihydrozeatin-O-β-D-glucoside and zeatin ribotide-O-β-D-glucoside. [8-14C-]Dihydrozeatin appeared to be rapidly metabolized to dihydrozeatin ribotide when supplied to segments of stems from decapitated plants. These results are discussed in relation to the metabolism and distribution of cytokinins in the whole plant.
79 citations
TL;DR: Although water contents and osmotic potentials continued to decline over the eight-day period of stress, ABA fell rapidly after day 2, reaching normal levels by day 8, and zeatin levels remained depressed throughout the stress period but rose rapidly after stress relief, and plant growth followed a similar pattern.
75 citations
TL;DR: A second cytokinin, zeatin, has been identified by its chromatographic behavior and mass spectrum including chemical ionization mass spectrometry of its permethyl derivative.
Abstract: Gametophore-over-producing mutants of the moss, Physcomitrella patens, when grown in liquid culture export high levels of cytokinin into their culture medium. The cytokinin produced by these mutants is postulated to account for their peculiar phenotype, that of mosses treated with exogenous cytokinin. N6-(Δ2-isopentenyl)adenine, the major cytokinin, has been identified previously in two of these mutants (Wang, Cove, Beutelmann, Hartmann 1980 Phytochemistry 19: 1103-1105) and now in additional representatives. A second cytokinin, zeatin, has been identified by its chromatographic behavior and mass spectrum including chemical ionization mass spectrometry of its permethyl derivative.
62 citations
TL;DR: The stability of 8- 14 C-analogues of zeatin,Zeatin-O-β-D-glucoside, dihydrozeatin and dihydrzeatin has been studied in detached leaves and major metabolites appeared to be major metabolites; minor metabolites included adenine, adenosine, and a range of glucoside-like conjugates.
54 citations
TL;DR: A cell line of Catharanthus roseus (L.) G. Don coded PRL # 200, was characterized with respect to its biosynthetic capabilities for indolealkaloids, in particular catharanthine, in suspension cultures.
Abstract: Callus derived from hypocotyls of periwinkle, Catharanthus roseus, responded to culture on nutrient media supplementedwith IAA, BA, and zeatin with shoot formation at low frequencies. However, shoot regenerating callus could be very successfully propagated and subcultured. Alkaloid profiles of callus derived from the original explants (hypocotyls) as well as callus derived from regenerated shoots were almost identical. Subcultures of old callus (initiated in 1978) failed completely to grow shoots. In programs for long-term preservation of alkaloid producing cell lines by regeneration and storage of shoots, selection for ability to form shoots would have to precede selection for alkaloid production.
48 citations
44 citations
TL;DR: Growth stimulation of excised cotyledons by cytokinins apparently involves wall loosening, in addition to previously demonstrated increases of K(+) absorption and formation of reducing sugars.
Abstract: The mechanism of cytokinin-induced cell expansion in cotyledons excised from dark-grown seedlings of radish ( Raphanus sativus L.) and cucumber ( Cucumus sativus L.) was studied. Cotyledons were incubated in dim light with or without 17 micromolar zeatin for periods up to 3 days. Fresh weights and osmotic potentials were measured daily. Cell wall extensibility properties were measured before and after the growth period. Also, experiments in which radish cotyledons were grown in mannitol solutions of various concentrations were performed. Comparisons of growth rates and increases of tissue osmotic potentials (toward zero) during growth without mannitol indicate that wall extensibility increased during the growth period and that this extensibility was enhanced by zeatin. Extensibility values derived from growth rates in mannitol provided indirect evidence of zeatin-increased wall extensibility. These conclusions were verified by direct measurements of plasticity with an Instron extensiometer. Thus, growth stimulation of excised cotyledons by cytokinins apparently involves wall loosening, in addition to previously demonstrated increases of K + absorption and formation of reducing sugars.
43 citations
TL;DR: Root regenerarion occurred in high frequency only when the differentiated shoots were recultured on sucrose-free 1 2 strength MS medium supplemented with 1 μM indolebutyric acid (IBA), and regenerated plantlets were maintained in vitro at 26°C for over 2 years without periodic transfer and some of them were successfully grown in pots.
41 citations
TL;DR: Cytokinins were extracted from plasmodia and from the remaining host cytoplasm and the different glucosides were determined after treatment of the water fraction with β-glucosidase.
Abstract: Plasmodia have been isolated from Brassica campestris tissue infected with Plasmodiophora brassicae. Cytokinins were extracted from plasmodia and from the remaining host cytoplasm. Fractions were separated in a butanol soluble fraction containing free cytokinins and a water soluble fraction containing bound forms, presumably glucose-6-phosphate derivatives of zeatin and zeatin riboside. The butanol fraction was analysed by high pressure liquid chromatography (HPLC). The different glucosides were determined after treatment of the water fraction with β-glucosidase.
40 citations
TL;DR: One to five percent of Lycopersicon peruvianum (L.) Mill undergo cell division and concomitant organization to form embryogenic-like structures when cultured in Murashige and Skoog medium (1962).
Abstract: One to five percent of Lycopersicon peruvianum (L.) Mill. leaf mesophyll protoplasts undergo cell division and concomitant organization to form embryogenic-like structures when cultured in Murashige and Skoog medium (1962) containing 3% sucrose, 9% mannitol, 1.0 mg/l kinetin (K) and 1.0 mg/l naphthalene acetic acid (NAA) at pH 5.6–5.8 (medium A). These embryogenic structures, after passing through developmental stages similar to those observed in zygotic embryogeny, are capable of forming shoots on hormone-free medium A. In medium B, wherein 0.5 mg/l of 2,4-dichlorophenoxyacetic (2,4-D) replaced the hormones (K and NAA), embryogenic structures did not develop. However, callus originating in medium B retained morphogenetic capacity as was evidenced by subsequent shoot regeneration when they were transferred to medium A with K and NAA replaced by 1.0 mg/l zeatin (Z). The potential value of incorporating this regeneration trait into Lycopersicon species and cultivated lines for use in tissue culture programs is discussed.
TL;DR: Callus cultures were established from the scutellum, scutellar node and radicle region of immature embryos of rye and octoploid triticale on modified Murashige-Skoog basal medium supplemented with various growth regulators.
Abstract: Callus cultures were established from the scutellum, scutellar node and radicle region of immature embryos of rye and octoploid triticale on modified Murashige-Skoog basal medium supplemented with various growth regulators. 2, 4-D, 2, 4, 5-T and 2, 4, 5-Cl, POP were found suitable for initiation and maintenance of callus cultures. Cytokinins had no or inhibitory effect on callus induction and growth. On basal medium containing 5 mg/l of 2,4,5-Cl3 POP, 16% of triticale and 17% of rye primary cultures exhibited shoot bud regeneration after 3–4 weeks. Transfer of such cultures to basal medium supplemented with zeatin or zeatin in combination with IAA further promoted shoot elongation and plantlet formation. Plantlets were rooted on basal medium containing 1 mg/l NAA and were eventually transferred to soil. Chlorophyll variants were observed in about 6% of triticale cultures.
TL;DR: The cytokinin content of the root exudate and leaves of white lupin plants (Lupinus albus L) was investigated at 2 weekly intervals after anthesis of the lowest flower on the primary inflorescence as discussed by the authors.
Abstract: The cytokinin content of the root exudate and leaves of fruiting white lupin plants (Lupinus albus L.) was investigated at 2 weekly intervals after anthesis of the lowest flower on the primary inflorescence. Up to 8 weeks after anthesis the level of cytokinins in the root exudate increased. However, at 10 weeks after anthesis insufficient sap was produced for analysis. Cytokinins co-eluting with zeatin and zeatin riboside were detected in the root exudate after fractionation on Sephadex LH-20. The cytokinin levels in the mature leaves steadily increased up to 8 weeks after anthesis and thereafter remained relatively constant. Three peaks of activity, co-eluting with zeatin, zeatin riboside and the glucoside cytokinins were recorded in the leaf extracts. The level of glucoside cytokinins in the leaves was high at 8 and 10 weeks after anthesis. Paper chromatography of extracts of fruits collected at 2 weeks after anthesis indicated that as fruit development proceeded there was a build up of cytokinin in this region of the plant. It is suggested that, in the white lupin, the cytokinins translocated to the shoot are accumulated in the leaves and in the fruits and that it is only later when there is a considerable decrease in sap (10 weeks after anthesis) production that a decreasing supply of cytokinins leads to shoot senescence.
TL;DR: The results contradict the hypothesis of de novo synthesis of cytokinins in roots of intact bean plants and find strong indications for their dependency.
Abstract: Roots of intact bean plants were supplied with [14C]adenine by pulse-chase experiments. The rate of incorporation of radioactivity into tRNA and oligonucleotides of roots as well as the content of radioactive labeled cytokinin nucleotides in these RNA fractions were determined. On the average, 1/70 of the radioactivity incorporated into tRNA was localized in N6(Δ2isopentenyl)adenosine. The half life of tRNA was estimated to be 65–70 h. Shortly after the pulse period, oligonucleotides contained zeatin riboside at a ratio of 1:800, on the basis of radioactivity. The half life of these oligonucleotides was determined to be about 8 h. The main free radioactive cytokinin of roots and leaves was zeatin. Comparing the rate of degradation of 14C-labeled tRNA and the oligonucleotides of roots and the rate of appearance of radioactive cytokinins in roots and leaves, we found strong indications for their dependency. The results contradict the hypothesis of de novo synthesis of cytokinins in roots of intact bean plants.
TL;DR: The development of virescent flowers as a result of the infestation of Catharanthus roseus plants by different “strains” of mycoplasmas could be correlated with marked changes in the levels of endogenous cytokinins within the flowers, mature leaves and roots of the plants.
Abstract: The development of virescent flowers as a result of the infestation of Catharanthus roseus plants by different “strains” of mycoplasmas could be correlated with marked changes in the levels of endogenous cytokinins within the flowers, mature leaves and roots of the plants In all cases, the cytokinin levels in the roots and mature leaves decreased while that in the flowers increased Three peaks of cytokinin activity which co-eluted with glucosylzeatin, ribosylzeatin and zeatin respectively were detected in these organs No qualitative differences in the cytokinin complement of the infected plants were detected At present it is not known whether or not the mycoplasmas used synthesize cytokinins which upset the cytokinin balance of Catharanthus roseus plants or are responsible for changes in the synthetic capacity and/or translocation pattern of the infested plants
TL;DR: In vitro vegetative multiplication of sugarbeet was obtained by culturing of inflorescence explants and Gibberellic acid (GA3) enhanced the process.
Abstract: In vitro vegetative multiplication of sugarbeet was obtained by culturing of inflorescence explants. Subapical segments or 5-mm-long tips from nine varieties developed axillary shoots (up to 50 per tip) on a medium containing indolebutyric acid (IBA) and benzylaminopurine (BAP). Zeatin was ineffective as cytokinin. Gibberellic acid (GA3) enhanced the process. Such vegetative shoots were subsequently isolated and were each allowed to develop up to 20 supplementary axillary shoots on a multiplication medium containing IBA, BAP, and naphthaleneacetic acid (NAA). Rooting of shoots was obtained in the absence of growth regulators and plants were established.
TL;DR: Evidence was obtained which indicates that cytokinins are apparently both produced and utilised at low temperatures, and it would appear that their production occurs in the bark and that they are utilised within the buds.
TL;DR: Results suggest that stared cytokinin glucosides from Yucca leaves are, converted by β-glucosidase in leaves and stem, transported through the inflorescent stalk as zeatin nucleotides.
Abstract: Transport and metabolism of 8-14 C-zeatin, applied to an attached de-tipped one-year-old mature leaf of a Yucca plant bearing a bleeding inflorescent stalk, has been studied. Radioactive zeatin ribotide was found in the exudate of the bleeding inflorescence, which was collected over a period of 5 days. Radioactive zeatin ribotide was mainly extracted from the fed leaf. Minor conversion products in this leaf were zeatin ribotide, zeatin-o-β-glucoside and zeatinriboside o-β-glucoside.
In not zeatin fed plants, zeatin-o-β-glucoside was tentatively identified as the main endogenous cytokinin in one-year-old mature leaves. In the bleeding sap of not treated plants no free bases of zeatin or zeatin ribosides were found. After alkaline phosphatase treatment zeatin-riboside was detected by combined gas chromatography-mass spectrometry, indicating the presence of zeatin ribotide in the bleeding sap. High β-glucosidase activity was found in the stern.
Results suggest that stared cytokinin glucosides from Yucca leaves are, converted by β-glucosidase in leaves and stem, transported through the inflorescent stalk as zeatin nucleotides.
TL;DR: The transport and metabolism of 8[14C]t-zeatin applied to the embryonic axis and radicle tip of Zea mays L. caryopses was studied and showed the predominant way in which applied zeatin was metabolised in the metabolically more active embryonic axis.
Abstract: The transport and metabolism of 8[14C]t-zeatin applied to the embryonic axis and radicle tip of Zea mays L. caryopses was studied. As in the endosperm side-chain oxidation rather than side-chain modification (glucosylation) was the predominant way in which applied zeatin was metabolised in the metabolically more active embryonic axis. Within this tissue there was also evidence for a second form of metabolism which involved modifications to the adenine ring. No clear evidence for an embryo-endosperm interactions of cytokinins during the course of germination process could be found.
TL;DR: The cytokinins kinetin and zeatin increased stomatal opening at 15°C in the dark by up to 50% in detached epidermis of the CAM plant Kalanchoe daigremontiana and opened maximally following incubation with 10 mmol m-3 cytokinin.
Abstract: The cytokinins kinetin and zeatin increased stomatal opening at 15°C in the dark by up to 50% in detached epidermis of the CAM plant Kalanchoe daigremontiana. Stomata opened maximally following incubation with 10 mmol m-3 cytokinin. This study extends the range of species in which exogenous cytokinins promote stomatal opening.
TL;DR: Isozyme investigations reyealed varying patterns in growing and differentiating callus and a correlation between isozyme expression and differentiation process is discussed.
TL;DR: In this paper, pyruvaldehyde dimethylacetal and acetonitrile in the presence of sodium methoxide, followed by acid hydrolysis to give 58% overall yield on distillation.
Abstract: (E)-3-Formylbut-2-enenitrile (4) is synthesized in 2 steps by reacting pyruvaldehyde dimethylacetal and acetonitrile in the presence of sodium methoxide, followed by acid hydrolysis to give 58% overall yield on distillation. The aldehyde4 can be stepwise and selectively reduced to (E)-3-hydroxymethylbut-2-enylamine (7a) in 37% total yield or exhaustivelyb reduced in 1 step to (±)-4-hydroxy-3-methylbutylamine (6) in 46% total yield. Compound7a and6 can be condensed with 6-chloropurine to give zeatin and (±)dihydrozeatin respectively. This provides a readily accessible method for isotope-labelled zeatin and its derivatives at side chain.
TL;DR: In this paper, five cytokinins, trans-zeatin, 9-β-d -ribofuranosyl- trans -zeatin and 6-(trans -4- O -β- d -glucopyranosyl -3-methyl-2-butenylamino)purine were identified from immature seeds of Dolichos lablab.
TL;DR: Comparative analyses of retained and naturally abscising cotton fruits showed that abscission was negatively correlated with the concentration of cytokinins, and one fraction was tentatively identified as zeatin ribonucleotide and another was chromatographically indistinguishable from zeatIn.
Abstract: SummaryThe cytokinins in developing cotton fruit were isolated, partially purified and separated on polyvinylpyrrolidone columns into at least five fractions of activity. One fraction was tentatively identified as zeatin ribonucleotide and another was chromatographically indistinguishable from zeatin. Additional fractions were not identified. The changes in concentration of total cytokinins during the growing season were studied in relation to seed and fruit development, fruit growth and abscission. Correlations between cytokinin level, meristematic activity in the seed in the form of a cellular endosperm and growth rate of the fruit during phase II (10–20 days after anthesis) of its sigmoid growth were observed. Comparative analyses of retained and naturally abscising cotton fruits showed that abscission was negatively correlated with the concentration of cytokinins.
TL;DR: Developing fruits of jujube, Ziziphus mauritiana Lam.
TL;DR: Root nodules ofPhaseolus mungo were extracted for their cytokinin content and Rf values obtained by co-chromatography with authentic samples of cytokinins on thin layer of a mixture of polyvinylpyrrolidone/CaSO4 were obtained.
Abstract: Root nodules ofPhaseolus mungo were extracted for their cytokinin content Four cytokininsviz zeatin, zeatin riboside, N6(‡2-isopentenyl) aminopurine and its riboside were identified on the basis of Rf values obtained by co-chromatography with authentic samples of cytokinins on thin layer of a mixture of polyvinylpyrrolidone/CaSO4
TL;DR: There was no indication that butanol-soluble cytokinins, as quantified by the soyabean callus bioassay in terms of zeatin equivalents, were synthesized or produced in Chrysanthemum shoots since, although small quantities of cytokinin were detected in the agar, a greater amount of these phytohormones was lost from the shoots during diffusion.