Showing papers on "Zeatin published in 1990"
TL;DR: Judging from their activity, concentrations and response to depodding, DZR and ZR may be the most important senescence retardants in soybean xylem sap.
Abstract: Cytokinins (CKs) coming from the roots via the xylem are known to delay leaf senescence, and their decline may be important in the senescence of soybean (Glycine max) plants during pod development (monocarpic senescence). Therefore, using radioimmunoassay of highly purified CKs, we quantified the zeatin (Z), zeatin riboside (ZR), the dihydro derivatives (DZ, DZR), the O-glucosides, and DZ nucleotide in xylem sap collected from root stocks under pressure at various stages of pod development. Z, ZR, DZ, and DZR dropped sharply during early pod development to levels below those expected to retard senescence. Pod removal at full extension, which delayed leaf senescence, caused an increase in xylem sap CKs (particularly ZR and DZR), while depodding at late podfill, which did not delay senescence, likewise did not increase the CK levels greatly. The levels of the O-glucosides and the DZ nucleotide were relatively low, and they showed less change with senescence or depodding. The differences in the responses of individual CKs to senescence and depodding suggest differences in their metabolism. Judging from their activity, concentrations and response to depodding, DZR and ZR may be the most important senescence retardants in soybean xylem sap. These data also suggest that the pods can depress CK production by the roots at an early stage and this decrease in CK production is required for monocarpic senescence in soybean.
136 citations
TL;DR: The effectiveness of several different cytokinins at enhancing Malus and Rubus organogenesis was related to the shoot proliferation activity of the cytokinin and to treatment-induced variation in leaf and petiole size.
Abstract: Shoot regeneration from Rubus leaves was obtained on a medium containing MS salts, vitamins and sugars, Staba vitamins, casein hydrolysate (100 mg l−1) and 10 μM thidiazuron. Shoot regeneration from Malus leaves was obtained on N6 rice anther medium with 5 μM thidiazuron. In vitro pretreatment of source shoots with either colchicine or thidiazuron enhanced the organogenic potential of detached leaves of two Rubus hybrids. The response to colchicine was quadratic and occurred at non-mutagenic concentrations (75–250 μM). The response to thidiazuron was exponential between 0 and 5 μM. When applied as a pretreatment, the effectiveness of several different cytokinins (benzyladenine, thidiazuron, zeatin) at enhancing Malus and Rubus organogenesis was related to the shoot proliferation activity of the cytokinin and to treatment-induced variation in leaf and petiole size.
74 citations
TL;DR: Stable cell suspension cultures were established from two types of calli derived from cultured immature embryos of wheat and only the embryogenic suspension derived from the aged, compact and nodular callus formed distinct somatic embryos when plated on regeneration media containing IAA and zeatin.
Abstract: Stable cell suspension cultures were established from two types of calli (one compact, nodular and embryogenic, the other friable and embryogenic) derived from cultured immature embryos of wheat (cv FLA302). Only aged calli, which had been subcultured for at least 5–8 months, formed suspensions comprised mainly of groups of small, round, densely cytoplasmic, starch-containing cells. Only the embryogenic suspension derived from the aged, compact and nodular callus formed distinct somatic embryos when plated on regeneration media containing IAA and zeatin. Upon subsequent transfer to fresh regeneration medium more than 200 green rooted plants were obtained.
64 citations
TL;DR: Effects depended on the amount of cytokinin applied and were of greater mag- nitude with benzyladenine than with zeatin, which had a 90% longer shelf life than controls.
Abstract: Broccoli (Brassica oleracea L. var. italica 'Citation') florets were treated postharvest with either benzyladenine or trans-zeatin at either 10 or 50 ppm before packaging in perforated polyethylene bags and storage at 16C. The most pronounced effects were observed with benzyladenine at 50 ppm. Compared to controls, respiration rate was reduced 50% and ethylene production increased 40% throughout the first 4 days of storage. Total chlorophyll content had dropped 60% in controls, but was unchanged in cytokinin-treated florets, which had a 90% longer shelf life than controls. These effects depended on the amount of cytokinin applied and were of greater mag- nitude with benzyladenine than with zeatin.
63 citations
TL;DR: Callus cultures were initiated from immature cotyledons of Vigna aconitifolia, V. mungo and V. radiata on MS medium supplemented with NAA, picloram or 2, 4-D and large number of somatic embryos differentiated from the callus.
50 citations
Journal Article•
TL;DR: A simple, defined medium has been standardized for the mass multiplication and production of virus-free plants of Pogostemon cablin (Blanco) Benth, and multiple shoot proliferation is exhibited.
Abstract: A simple, defined medium has been standardized for the mass multiplication and production of virus-free plants of Pogostemon cablin (Blanco) Benth. Shoot meristems cultured on Murashige and Skoog's (1962) medium (MS) supplemented with 2.0 mg I −1 6-benzylaminopurine (BAP) or 0.5-2.0 mg I −1 6-γ,γ--dimethylallyaminopurine (2iP) or 0.5-2.0 mg I −1 zeatin (Z) and 1.0 mg I −1 indole-3-acetic acid (IAA) exhibited multiple shoot proliferation. Regenerated shoots readily rooted on half-strength MS containing 1.0 mg I −1 IAA or α-naphthaleneacetic acid (NAA) and 1.5% sucrose. Rooted plantlets were transferred to pots, hardened in the glasshouse and grown to maturity in the field with a high rate (80-90%) of survival
50 citations
TL;DR: Although the addition of cytokinin was needed for embryo formation for some plants, in no instance were cytokinins able to replace the inductive effect of high-temperature treatments.
Abstract: Anther culture medium was prepared with different types and concentrations of cytokinins to gain greater insight into the control of embryo formation during Brassica oleracea L. var. italica (broccoli) anther culture. The independent addition of the four cytokinins tested had widely divergent effects dependent upon cytokinin concentration and the genetic background of the test plants. All cytokinins were generally inhibitory at high concentrations, however, individual plants showed significant stimulation of embyro formation at typical physiological levels. The influence of cytokinins was highly cultivar-specific, some lines were stimulated, others inhibited and still other test lines were largely unaffected. Although the addition of cytokinins was needed for embryo formation for some plants, in no instance were cytokinins able to replace the inductive effect of high-temperature treatments.
43 citations
01 Jan 1990
TL;DR: Cytokinins in apices of eight isogenic lines of Mercurialis annua were compared (high performance liquid chromatography-gas chromatography mass spectroscopy computer system) as mentioned in this paper.
Abstract: Cytokinins in apices of eight isogenic lines of Mercurialis annua were compared (high performance liquid chromatography-gas chromatography mass spectroscopy-computer system). These apices develop normal staminate or pistillate differentiation processes (sex series lines) or empty (sterile), semiempty (semisterile), and full anthers (restored fertile male) in the sterility series in which a pistillate line was constructed. Both series developed two different cytokinin pathways: trans-cytokinins characterized the sex series, whereas the cis pathway characterized the sterility series. Drastic changes in the trans pathway (0/250 nanograms trans-zeatin and 166/0 nanograms zeatin nucleotide) induced
42 citations
TL;DR: In addition to their effects on vascular tissue regeneration, both cytokinins promoted callose production and were most evident on the sieve plates of the regenerated sieve tube members and on the walls of the parenchyma cells around the wound.
Abstract: Cytokinin proved to be a controlling factor in sieve tube regeneration around wounded collateral bundles in an in vivo system in which the endogenous cytokinin level had been minimized. Both kinetin and zeatin were applied in aqueous solution to the bases of excised, mature internodes of Coleus blumei Benth. that had an active vascular cambium. Each internode also received indoleacetic acid (IAA) in lanolin at its apical end. Under either low (0.1% w/w) or high (1.0% w/w) auxin concentrations, the control internodes (without exogenous cytokinin) exhibited small amounts of sieve tube regeneration. At appropriate concentrations, both kinetin and zeatin induced a significant increase in sieve tube regeneration around the wound. However, the highest concentration of kinetin tested (50 μg/mL) completely inhibited this process. Kinetin was the most effective with high auxin (1.0% IAA), while zeatin was the most effective with low auxin level (0.1% IAA). Kinetin and zeatin showed the strongest promotive effect at 10 μg/mL and 20 μg/mL, respectively. Both cytokinins also induced supplementary phloem regeneration further from the wound surface. In addition to their effects on vascular tissue regeneration, both cytokinins promoted callose production. This was most evident on the sieve plates of the regenerated sieve tube members and on the walls of the parenchyma cells around the wound. The largest deposits of callose were found in both regenerated sieve tube members and parenchyma cells at the highest cytokinin concentration tested (50 μg/mL). The possible role of cytokinin in controlling callose accumulation in the sieve tubes during autumn is discussed.
41 citations
TL;DR: Time taken from plating protoplasts to obtaining plantlets is 8–10 weeks, using this procedure, several hundred regenerated plants have been hardened in a growth chamber and transferred to soil.
Abstract: Protoplasts derived from hypocotyls of seedlings grown on half-strength MS medium containing 1% sucrose were cultured at a density of 5×104 ml-1 in Kao's medium supplemented with 1.0 mgl-12,4-D, 0.1 mgl-1 NAA and 0.5 mgl-1 zeatin riboside. After three days of culture in darkness at 25±1°C, cultures were transferred to light (70 μEm-2s-1) in a 16/8 h ligo ht/dark cycle. Cultures were diluted on the 7th, 10th and 13th day with Kao's medium containing 3.4% sucrose, 0.1 mgl-1 2,4-dichlorophenoxyacetic acid and 1.0 mgl-1 benzyladenine. On the fifteenth day, microcalli were plated on K3 medium gelled with 0.5% agarose (Type 1, low EEO, Sigma). After a further period of two weeks, transfers were made to specific media to achieve either organogenesis or somatic embryogenesis. Time taken from plating protoplasts to obtaining plantlets is 8–10 weeks. Using this procedure, several hundred regenerated plants have been hardened in a growth chamber and transferred to soil.
41 citations
TL;DR: The embryonic axis plays an essential role in the mobilization of the main reserves of the cotyledons of seeds of Cicer arietinum L. cv Castellana and the principal regulatory role of the endogenous cytokinins concerns the metabolism of carbohydrates and proteins; there is less influence on lipid metabolism.
Abstract: The embryonic axis plays an essential role in the mobilization of the main reserves of the cotyledons of seeds of Cicer arietinum L. cv Castellana. This control by the axis of the metabolism of the storage products of the cotyledons largely takes place through the cytokinins, which are transported from the embryonic axis to the cotyledons where the mobilization of reserves begins. The principal regulatory role of the endogenous cytokinins concerns the metabolism of carbohydrates and proteins; there is less influence on lipid metabolism. However, each cytokinin seems to have a different role in the mobilization processes. The glucosides, glucosyl zeatin riboside, and glucosyl zeatin act only as storage forms of the hormones. Zeatin riboside affects mainly the mobilization of carbohydrates and has less effect on protein mobilization. Zeatin regulates both the mobilization of carbohydrates and that of proteins and is more marked in the latter case.
TL;DR: Results provide further evidence that growth regulators can be used for the tissue culture of seaweeds and for the study of developmental phenomena in these plants.
Abstract: We examined whether auxins and cytokinins, either singly or in combination, stimulate cell division in tissue cultures of a red seaweed. Our experimental model consisted of filamentous and callus-like growths that developed from cross-sectional discs cut from young branches of Agardhiella subulata. Plant growth regulators were added to the medium to give combinations of an auxin with a cytokinin over a range of concentrations (1 µg L−1 −10 mg L−1). Several mixtures of auxins and cytokinins, as well as some single auxins, cytokinins and phenolics, stimulated cell division and growth in the tissue cultures beyond that of controls. The treatments that were effective included: phenylacetic acid/zeatin; phenylacetic acid/6-benzylaminopurine; α-naphthaleneacetic acid/zeatin; 2,4,5-trichlorophenoxyacetic acid/6-benzylaminopurine; and indoleacetic acid/kinetin. High concentrations of cytokinins (i.e. 10 mg L−1) inhibited the regeneration of plants in some of the cell cultures. These results provide further evidence that growth regulators can be used for the tissue culture of seaweeds and for the study of developmental phenomena in these plants.
TL;DR: Relatively high concentrations of cytokinin-like substances in petiole phloem sap coincided in time with high concentrations in sap from the base of the inflorescence, consistent with movement of cytkinins from leaves into the developing inflorescence and fruit, rather than direct input to the fruit from xylem sap.
Abstract: Cytokinin-like activity in samples of xylem and phloem sap collected from field-grown plants of white lupin (Lupinus albus L.) over a period of 9 to 24 weeks after sowing was measured using the soybean hypocotyl callus bioassay following paper chromatographic separation. The phloem sap was collected from shallow incisions made at the base of the stem, the base of the inflorescence (e.g. stem top), the petioles, and the base and tip of the fruit. Xylem sap was collected as root exudate from the stump of plants severed a few centimeters above ground level. Concentration of cytokinin-like substances was highest in phloem sap collected from the base of the inflorescence and showed an increase over the entire sampling period (from week 10 [61 nanogram zeatin equivalents] to week 24 [407 nanogram zeatin equivalents]). Concentrations in the xylem sap and in the other phloem saps were generally lower. Relatively high concentrations of cytokinin-like substances in petiole phloem sap (70 to 130 nanogram zeatin equivalents per milliliter) coincided in time with high concentrations in sap from the base of the inflorescence (see above). Concentrations in sap (phloem or xylem) from the base of the stem were very much lower. This finding is consistent with movement of cytokinins from leaves into the developing inflorescence and fruit, rather than direct input to the fruit from xylem sap. However, an earlier movement of cytokinins from roots into leaves via the xylem cannot be ruled out. Sap collected at an 18-week harvest was additionally separated by sequential C18 reversed-phase high performance liquid chromatography → NH2 normal phase high performance liquid chromatography, bioassayed, and then analyzed by electron impact gas chromatography-mass spectrometry. Identification of zeatin riboside and dihydrozeatin as two of the major cytokinins in combined sap samples was accomplished by gas chromatography-mass spectrometry-selected ion monitoring.
TL;DR: Three superior clones of Eucalyptus grandis hybrids were micropropagated through several steps to induce juvenile sprouts and regular subculture on the multiplication medium improved rooting significantly.
Abstract: Three superior clones of Eucalyptus grandis hybrids were micropropagated through several steps. Five-year-old trees were girdled to induce juvenile sprouts. Cultures were attempted from mature branches and sprouts. Branches from mature trees were 100% contaminated while sprouts were only 40% contaminated. Pre-initiation hormone free medium and dark environment were used to screen for contaminants and to reduce production of phenolic compounds. Initiation of auxillary buds was achieved with modified MS plus 0.05 mg/l NAA and 0.5 mg/l BAR High multiplication rates were obtained on auxin-free medium with 0.6 mg/1 BAR Elongation of shoots was best on media with high auxin (2.5 mg/l of IBA) and cytokinin (1–1.5 mg/l of zeatin). Continual subculture on the multiplication medium improved rooting significantly. Up to 98% rooting was achieved on 1/4 MS with 2 mg/l IBA. Rooted propagules were successfully transferred to a mist greenhouse with 82% survival, and then to greenhouse conditions.
TL;DR: In this article, the authors compared eight isogenic lines of Mercurialis annua with high performance liquid chromatography-gas chromatography mass spectroscopy-computer system and found that the complete cis-pathway was morphologically effective in the sterility series when the ratio of cis to trans pathways was 1:2 or 1:1 instead of 1:3.
Abstract: Cytokinins in apices of eight isogenic lines of Mercurialis annua were compared (high performance liquid chromatography-gas chromatography mass spectroscopy-computer system). These apices develop normal staminate or pistillate differentiation processes (sex series lines) or empty (sterile), semiempty (semisterile), and full anthers (restored fertile male) in the sterility series in which a pistillate line was constructed. Both series developed two different cytokinin pathways: trans-cytokinins characterized the sex series, whereas the cis pathway characterized the sterility series. Drastic changes in the trans pathway (0/250 nanograms trans-zeatin and 166/0 nanograms zeatin nucleotide) induced staminate/pistillate differentiations. Less drastic quantitative changes in the cis pathway induced sterility or restored fertility compared to normal fertile anthers (192 or 669 nanograms/traces). The action of the complete cis-pathway was morphologically effective in the sterility series when the ratio of cis to trans pathways was 1:2 or 1:1 instead of 1:3. A final diagram shows the action of each sex or sterility allele on the enzymes controlling specific metabolites in both pathways. The discussion provides insights on the regulation of cytokinin-auxin balances specific for each kind of reproductive differentiation.
TL;DR: The significance of the results is discussed in terms of the relative importance of several factors: transpiration, cytokinin synthesis in roots and above-ground tissues, and mobilization of storage cytokinins in early spring.
TL;DR: Immunoaffinity techniques using columns of immobilized antibodies raised against zeatin riboside and isopentenyladenosine were found to be effective in isolating cytoklnins from vegetative, female, and male buds of Douglas-fir.
Abstract: Immunoaffinity techniques using columns of immobilized antibodies raised against zeatin riboside and isopentenyladenosine were found to be effective in isolating cytoklnins from vegetative, female, and male buds of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco). The purified cytokinins were separated by reverse phase high performance liquid chromatography and analyzed by radioimmunoassay. Confirmation of cytokinin identities was by gas chromatography-mass spectrometry. Immediately prior to bud burst, all bud types contained three major cytokinins: isopentenyladenosine, zeatin riboside, and a hexose conjugate of zeatin riboside (not zeatin riboside O-glucoside). Zeatin-type cytokinins were present in relatively high concentration in vegetative and female buds. In male buds, however, relatively high levels of isopentenyladenosine were found together with low levels of zeatin-type cytokinins.
TL;DR: Sucrose as plasmolyticum in the protoplast growth medium improved survival and increased the divisions during the initial growth phase.
TL;DR: Explants from flower stalks of Nicotiana tabacum L. were cultured on different cytokinins to induce flower bud formation and it was concluded that the free cytokinin base is the main active compound.
Abstract: Explants from flower stalks of Nicotiana tabacum L. were cultured on different cytokinins to induce flower bud formation. All cytokinins tested except zeatin and zeatin-riboside induced the same maximal number of flower buds. Benzyladenine, benzyladenosine, and dihydrozeatin were the most active compounds whereas isopentenyladenosine and isopentenyladenine acted at a 20-fold higher concentration. These data suggest that the active cytokinins bind to the same receptor with different affinities. The presence of benzyladenine in the medium was necessary only during the first 2 days of culture (initiation period). The equilibrium between benzyladenine and its conjugates (the riboside, glucoside, and nucleotides) after a 4-day pulse was independent of the benzyladenine concentration whether it was inductive or noninductive for bud formation. The level of all derivatives was proportional to the benzyladenine concentration in the medium. Isopentenyladenine was used as a competitive inhibitor of benzyladenine conjugation. Isopentenyladenine concentrations that were too low for bud formation led to a synergistic increase in bud number when applied together with benzyladenine. Isopentenyladenine decreased benzyladenine uptake and conjugation. In spite of the lower uptake, the concentration of free benzyladenine inside the explants was higher in the presence of isopentenyladenine than in its absence whereas the concentration of the 7-glucoside of benzyladenine was lower. It was concluded that the free cytokinin base is the main active compound.
TL;DR: Radioactivity was found to be incorporated into zeatin nucleotide indicating that the embryo in the germinating seed is capable of cytokinin biosynthesis.
Abstract: The embryos of germinating Zea mays seed were supplied with [14C]-adenine. Following incubation, the tissue was extracted and extensively purified by ion-exchange chromatography and thin layer chromatography. Radioactivity was found to be incorporated into zeatin nucleotide indicating that the embryo in the germinating seed is capable of cytokinin biosynthesis.
TL;DR: Benzyladenine induced the best proliferation responses, as shoot and node production, in Actinidia deliciosa cultivars ‘Hayward’ and ‘Tomuri’, while callus growth was enhanced on zeatin (Z)-enriched media.
TL;DR: Plant regeneration from cultured immature inflorescence segments of Eleusine coracana was obtained by direct shoot development and somatic embryogenesis and the majority of the regenerated plants showed the diploid chromosome constitution in their root tips.
Abstract: Plant regeneration from cultured immature inflorescence segments of Eleusine coracana was obtained by direct shoot development and somatic embryogenesis. Direct development of shoots from cultured inflorescence segments occurred on MS medium supplemented with 2,4-D in combination with zeatin. Inflorescences with well developed spikelets differentiated at a low frequency (<5%) from callus cultures initiated on media supplemented with 2,4-D in combination with zeatin or coconut water or picloram + kinetin. Somatic embryogenesis was also induced in callus cultures growing on MS + picloram + kinetin at the end of four passages. Supplementation of the media with different concentrations of sucrose showed 3% sucrose as the best concentration for plant differentiation from somatic embryos. The majority of the regenerated plants showed the diploid chromosome constitution in their root tips. The regenerants were in general shorter with an increased number of tillers compared to the control.
TL;DR: The two clones of hybrid poplar responded similarly to growth regulator treatments; however, the number of shoots produced was greater from the root organs derived from ‘Crandon’ clones.
Abstract: Excised roots of various ages from ‘Crandon’ and ‘Hansen’ clones of Populus alba x P. grandidentata were tested for their regeneration capacity. Sixty-day-old excised roots that contained root tips were found to be most suitable. The highest number of shoots (an average of 111 shoots/root segment with ‘Crandon’ and 98 with ‘Hansen’) was obtained by adding 22μM and 14μM zeatin to the medium, respectively. The two clones of hybrid poplar responded similarly to growth regulator treatments; however, the number of shoots produced was greater from the root organs derived from ‘Crandon’ clones. Regenerated shoots were rooted in basal Woody Plant Medium without any growth regulators. Successful transplantation into soil and growth was achieved with all plants.
TL;DR: Embryogenic competence was maintained throughout 10 months of regular subculturing and mature somatic embryos were achieved after transfer to Woody Plant Medium.
TL;DR: It is suggested that Z could regulate root elongation by acting on the IAA and/or ABA level, and the comparative action of these two hormones is discussed.
Abstract: Elongation, indolyl-3-acetic acid (IAA) and abscisic acid (ABA) levels, – gas chromatography-mass spectrometry quantification –, in the elongating zone were analysed for maize (Zea mays L., Cv. LG11) roots immersed in buffer solution with or without zeatin (Z). The effect of Z depends on the initial extension rate of roots. The slower growing roots are more strongly inhibited by Z (10−7−10−5M) and they show a greater increase in IAA and ABA content. When compared to the rapidly growing roots, the larger reactivity of the 'slow’ones cannot be attributed to a higher Z uptake as shown when using [14C]-Z. It is suggested that Z could regulate root elongation by acting on the IAA and/or ABA level. The comparative action of these two hormones is discussed.
TL;DR: Anthers containing microsporcs at miduninucleatc stage from live wheat cultivars and two octoploid trilicale lines were tested mainly for callus induction and polyhaploid production on each of the 11 media.
Abstract: Homozygous doubled-haploid plantlets derived from anther culture of wheat (Triticum aestivum L.) and triticale (×Triticosecale Wittmack) are useful breeding materials. However, efficiency of an-drogenesis needs improvement. We used media (basic components, are the same as 85DI2) each containing one of the seven auxins [2,4,5-trichlorophenoxyacetic acid (2,4,5–T), P-chloraphenoxyacetic acid (pCPA), 3,6-dichloro-o-anisic acid (dicamba), 4-amino-3,5,6-trichloropicolinic acid (picloram), indole-3-butrytic acid (IBA), indole-3-acctic acid (IAA), and 2,4-dichlorophenoxyacetic acid (2,4-D) as a control] in combination with 6-furturyl-aminopurine (kinetin). In addition, each of the four cytokinins [6-benzylaminopurine (6-HA), 2-isopenlylnyl adenine (2-ip), 6-(4-hydroxy-3-meihylbut-2-enylamino) purinc (zeatin), and kinetin as a control] was tested in combination with 1-naphthalene acetic acid (NAA). Anthers containing microsporcs at miduninucleatc stage from live wheat cultivars (Angus, Centurk, Chris, K.itt, and Pavon 76) and two octoploid trilicale lines (T81, T82) were tested mainly for callus induction and polyhaploid production on each of the 11 media. The cultivar × medium interaction was not significant, When averaged over all growth regulators, Pavon was (he best cultivar which produced 14.4 % calli and 23 % polyhaploid plantlets. Averaged over all cultivars, the medium containing 2, 4-U produced the highest calli (13.9 %). Undifferentiated calli were regenerated on 87T1 medium, which contained IAA (1 mg/1) and kinetin (2 mg/1).
TL;DR: High specific activity ZR was supplied to germinating seed and developing seedlings of Zea mays to study its metabolism and translocation and found aleurone tissue isolated from quiescent wheatgrains will not secrete amylase in response to gibberellicacid.
Abstract: High specific activity [ 3 H]-zeatin nboside (ZR) was supplied to germinating seed and developing seedlings of Zea mays to studyits metabolism and translocation The major metabolites of ZR in endosperm, embryo, and first leaves were adenosine, adenine,and adenine nucleotide When ZR was supplied to the radicle tip a significant proportion of the radioactivity extracted from theradicle was identified as zeatin-9-glucoside (Z9G). However, some ZR was also transported to the shoot and vestigial embryoDuring the initial stage of germination, movement of zeatin nboside from the embryo to the endosperm was pronounced but littlemovement occurred in the reverse directionKey words- Zea mays, cytokinin, zeatin nboside, metabolism, translocation INTRODUCTIONWhile the morphological and biochemical changes (Toole,1924; Tucker, 1957; Ingle and Hageman, 1965) in Zeamays seed during germination have been well defined,there are few studies of cytokinin metabolism and translo-cation in this seed or in other monocot seeds in relationto the germination process Endogenous cytokinins havebeen implicated in the control of monocot seed germina-tion. Thus, aleurone tissue isolated from quiescent wheatgrains will not secrete amylase in response to gibberellicacid (GA
01 Dec 1990
TL;DR: Expiants for establishing callus cultures originated from in vitro cultured hybrid poplar from stem internodes, leaf discs, and root segments and Regenerated shoots were easily rooted in polyterra™ peat plugs in transparent plastic boxes and transferred to pots containing an artificial potting mix.
Abstract: Expiants for establishing callus cultures originated from in vitro cultured hybrid poplar (Populus alba L X P grandidentata Michx) Plant regeneration was achieved from established callus cultures derived from stem internodes (SI), leaf discs (LD), and root segments (RS) Shoot regeneration from callus occurred within 4 weeks of culture on most of the media tested Frequency of shoot formation was greatly increased by subculturing the selected organogenic calli on regeneration media The highest rate of multiple shoot formation (an average number of 7/SI, 11/LD, and 8/RS) was obtained by using 005 μM IBA in combination with 225 μM 2iP, 225 μM zeatin, and 125 μM 2iP, respectively Regenerated shoots were easily rooted in polyterra™ peat plugs in transparent plastic boxes The rooted plantlets were subsequently transferred to pots containing an artificial potting mix
TL;DR: Zeatin binding varied with ionic strength, but could be detected using both precipitating (ammonium sulphate assay) and non-precipitating (equilibrium dialysis) conditions.