Showing papers on "Zeatin published in 1984"
TL;DR: The authors' entry into the polyamine field was accidental, but their attention was drawn to a report that the rapid senescence of detached leaves of this plant could be delayed substantially by the application of arginine, and this work was started on cereal leaf protoplasts.
514 citations
TL;DR: To obtain a high frequency of regeneration, rapidly growing calli were transferred to media having a high cytokinin:auxin ratio as early as possible, usually 3 weeks after protoplast isolation.
Abstract: Protoplasts isolated from 4-day-old hypocotyls of various species of Brassica (Brassica napus, B. campestris and B. oleracea) produced callus with high efficiency in media containing casein hydrolysate and high concentrations of the auxin 2,4-D (4.5 μM). Cell division began after 24 h and 60% of the cells had divided after 48 h. In contrast, protoplasts isolated from stem and mesophyll of plants grown in vitro or in the greenhouse began to divide after a delay of 3–5 days. In these cases 40–50% of the cells had divided after 5 days as compared to 70% for hypocotyl protoplasts. To obtain a high frequency of regeneration, rapidly growing calli were transferred to media having a high cytokinin:auxin ratio as early as possible, usually 3 weeks after protoplast isolation. The average regeneration frequency for calli obtained from mesophyll protoplasts was 50%, while as many as 70% of the calli derived from hypocotyl protoplasts of B. napus regenerated plantlets on a medium containing zeatin (9.1 μM) and IAA (0.6 μM). On the same medium regeneration of Brassica oleracea was obtained. A low percentage of calli (1%) from Brassica campestris formed shoots when cultured on a combination of zeatin (4.6 μM), BA (4.4 μM) and IAA (0.6 μM).
271 citations
TL;DR: Sample cytokinin levels estimated by radioimmunoassay were in close agreement to those available in the literature for similar samples assayed by alternative methods, however, in some samples, unknown cross-reacting compounds were detected.
Abstract: The cross-reactivity of antibodies elicited in rabbits against zeatin riboside, to a wide range of naturally occurring cytokinins, was examined. As well as to zeatin riboside, the antisera cross-reacted to a considerable extent with zeatin, lupinic acid, zeatin-9-glucoside, zeatin riboside 5′-monophosphate and to a much lesser, but measurable extent, with dihydrozeatin riboside and dihydrozeatin. Chromatographic methods were devised which allowed separation of all these cross-reactive compounds. Four biological samples, extracts of immature Zea mays kernels, immature seeds of Lupinus luteus, and Datura innoxia crown gall tumor tissue, and a sample of Agrobacterium tumefaciens culture supernatant, were purified by these chromatographic methods, using [3H]zeatin riboside as a recovery marker, and at each stage of the purification process, were subjected to radioimmunoassay over a range of dilutions. At each stage of sample purification, sample dilution curves were found to be parallel to the standard curve. Sample cytokinin levels estimated by radioimmunoassay were in close agreement to those available in the literature for similar samples assayed by alternative methods. However, in some samples, unknown cross-reacting compounds were detected.
81 citations
TL;DR: A two-stage in vitro technique was established for the development of interspecific hybrid embryos in the genus Lens, and the culture of 14-day-old fertilized ovules on MS medium supplemented with zeatin allowed theDevelopment of viable and vigorous plants.
Abstract: A two-stage in vitro technique was established for the development of interspecific hybrid embryos in the genus Lens. The culture of 14-day-old fertilized ovules on MS medium supplemented with zeatin, followed by the release of the embryos from the ovular integuments, allowed the development of viable and vigorous plants.
73 citations
TL;DR: Fragments of maize leaves were incubated at controlled temperature and irradiance either on distilled water or on one of three concentrations of cytokinin, and the effects of zeatin or kinetin on stomatal aperture were determined by stripping abaxial epidermis from the fragments after incubation and immediately measuringStomatal apertures under the microscope.
Abstract: Fragments of maize leaves were incubated at controlled temperature and irradiance either on distilled water or on one of three concentrations of cytokinin (10"', 10"2 and 10"3 mol m~3). The effects of zeatin or kinetin on stomatal aperture were determined by stripping abaxial epidermis from the fragments after incubation and immediately measuring stomatal apertures under the microscope. At each cytokinin concentration leaf pieces were incubated at 5 or 350 //mol mol"1 CO, with or without ABA ( 10 1 mol m"3). At 5-0 //mol mol"' C02 increasing the concentrations of zeatin had a negligible effect upon stomatal aperture. When air containing 350 //mol mol"1 CO, was bubbled through the incubation solutions, apertures of stomata incubated on water were more than halved. Increasing cytokinin concentrations reduced the effect of CO, on stomata and incubation on 10"1 mol m"3 zeatin completely removed any C02 response. The addition of ABA restored the effect of C02, even at the highest cytokinin concentration.
53 citations
TL;DR: Both ZR and O-glucosyl-ZR were metabolised extensively, withAdenine, adenosine, and adenine nucleotide(s) as the major metabolites, and a diversity of minor metabolites of ZR were identified, including O- glucosides, lupinic acid and dihydrol upinic acid.
Abstract: The activity, uptake and metabolism of cytokinin metabolites was determined in soybean (Glycine max (L.) Merr.) callus tissue. The following activity sequence was established: zeatin riboside (ZR)>zeatin (Z)>O-glucosides of Z, ZR and their dihydro derivatives>lupinic acid (an alanine conjugate of Z)>7- and 9-glucosides of Z which were almost inactive. The 7- and 9-glucosides and lupinic acid were taken up very slowly by the callus tissue and showed great metabolic stability, but some degradation to 7-glucosyladenine, 9-glucosyladenine and the 9-alanine conjugate of adenine occurred. Compared with its aglycone, O-glucosyl-ZR exhibited slow uptake and greatly enhanced stability but gas chromatographic-mass spectrometric analysis showed that appreciable amounts were hydrolyzed to ZR in the tissue. Both ZR and O-glucosyl-ZR were metabolised extensively, with adenine, adenosine, and adenine nucleotide(s) as the major metabolites. A diversity of minor metabolites of ZR were identified, including O-glucosides, lupinic acid and dihydrolupinic acid. The metabolism of ZR was suppressed by 3-isobutyl-1-methylxanthine. When compared with the soybean callus line normally used for cytokinin bioassays (cv. Acme, cotyledonary callus), related callus lines exhibited greatly differing growth responses to cytokinin: however, these were not reflected in marked differences in metabolism.
53 citations
TL;DR: Roots can be readily induced with IBA, but salt concentration and the physical support on which shoot-tips are grown influence both root initiation and growth, and half-strength salts and 1 μM IBA gave best root initiation.
49 citations
TL;DR: It is demonstrated that the endogenous cytokinin of tobacco crowngall tissue show a clear correspondence to the range of metabolites formed when exogenous cytokinins are supplied to nontumorous tobacco cells.
Abstract: the cytokinins of tobacco crown-gall tissue have been analysed by quantitative mass spectrometry using 2H2-labelled cytokinin riboside 5′-monophosphates and 15N4-labelled cytokinin glycosides as internal standards. The principal endogenous cytokinin of this tissue is zeatin riboside 5′-monophosphate. The biologically inactive 7-glucoside of zeatin is the most abundant basic cytokinin in the tissue. These findings expose the limitations of previously reported analyses of similar tissues, which were restricted to biologically active basic cytokinins. The present study demonstrates that the endogenous cytokinins of tobacco crowngall tissue show a clear correspondence to the range of metabolites formed when exogenous cytokinins are supplied to nontumorous tobacco cells.
47 citations
TL;DR: Based on detection and quantitation by bioassay, endogenous gibberellin-like substances and cytokinins in Pinus radiata D. don buds during sequential shoot initiation shift from less polar to more polar forms (GAs) and from conjugated to free forms (CKs).
Abstract: Based on detection and quantitation by bioassay, endogenous gibberellin-like substances (GAs) and cytokinins (CKs) in Pinus radiata D. Don buds during sequential shoot initiation shift from less polar to more polar forms (GAs) and from conjugated to free forms (CKs). As the terminal bud moves from the production of “short shoots” (needle fascicles) to “long shoots” (lateral branches or female conebuds), a more polar GA appears while a glucoside-conjugate of zeatin riboside is reduced, and zeatin riboside levels increase markedly. Permethyl derivatives of the two highly active CK fractions were examined by capillary gas chromatography-mass spectrometry after separation by C 18 reverse phase high performance liquid chromatography. The mass spectra indicated the presence of: 9-β-d-ribofuranosyl-6-(4-hydroxy-3-methyl-but-2-enylamino)purine (zeatin riboside) and 9-[hexosyl(probably glucosyl)-β-d-ribofuranosyl]-6-(4-hydroxy-3-methyl-but-2- enylamino)purine (a glycoside of zeatin riboside in which the glycosyl moiety is attached directly to the ribosyl moiety at an unknown position).
45 citations
TL;DR: EIA measurements showed that there was a concentration gradient of ZR + Z along the length of the Zea stem, and the five lowest internodes contained the highest concentrations toward their apical end, the region which included the node; this asymmetry was less pronounced near the top of the plant.
Abstract: A sensitive, specific enzyme immunoassay (EIA) for trans-zeatin riboside (ZR) and trans-zeatin (Z) in the 0.3 to 30 picomole range has been described. The reliability of the method for measuring ZR + Z in partially purified extracts of Zea mays L. tissues was verified by highperformance liquid chromatography. EIA measurements showed that there was a concentration gradient of ZR + Z along the length of the Zea stem. The topmost internodes, internodes 7 and 8 counting from the coleoptilar node, had the highest concentration ( approximately 130 picomoles per gram fresh weight). Moving basipetally, the concentration dropped approximately 10-fold to a minimum at internode 4, and then increased slightly in internodes 2 and 3. There were also gradients within each internode. The five lowest internodes contained the highest concentrations toward their apical end, the region which included the node; this asymmetry was less pronounced near the top of the plant.
42 citations
TL;DR: In this article, the authors showed that ABA was accumulated by the bud in relatively larger amounts during the final stages of bud dormancy (I-1 and I-2) than in the earlier stage (F-2).
Abstract: Summary
The dormant phase of the flush cycle of leaf growth in cocoa is known to be correlated with high abscisic acid (ABA) levels in the mature leaves of the new flush (NF) and previous flush (PF) leaves. Defoliation of either the NF leaves or PF leaves of cocoa seedlings reduced the length of the dormant phase of the flush cycle, thus showing that the mature leaves were a source of growth inhibitors which could affect shoot apical activity. The application of ABA to the NF and PF leaves led to an extension of the dormant phase, whereas application of zeatin or gibberellic acid decreased it. The distribution of [14C]ABA following its application to NF and PF leaves at different stages throughout the growth cycle showed that [14C] ABA was accumulated by the bud in relatively larger amounts during the final stages of bud dormancy (I-1 and I-2) than in the earlier stage (F-2). The results suggest that internal competition for nutrients may be responsible for the inhibition of growth at the F-2 stage but that ABA translocated from the mature leaves causes the buds to remain dormant during the subsequent stages of I-1 and I-2.
TL;DR: In this paper, it was shown that the effect of cytokinins is to change the growth form in the tip region of the side branches of the caulas of Funaria hygrometrica.
TL;DR: Using a trace-enrichment procedure involving solvent partitioning and high pressure liquid chromatography, followed by bioassay, two cytokinin-like substances believed to be zeatin and zeation riboside were detected in the xylem sap of sweet cherry.
Abstract: Using a trace-enrichment procedure involving solvent partitioning and high pressure liquid chromatography, followed by bioassay, two cytokinin-like substances believed to be zeatin and zeation riboside were detected in the xylem sap of sweet cherry (Prunus avium L.). The levels of cytokinin varied between rootstocks with the higher yielding and fruit setting rootstocks producing the highest cytokinin levels. Most of the cytokinin activity occurred in the spring during bloom and early fruit set. A relationship between cytokinin level in the xylem sap and fruit set is proposed.
TL;DR: Over 100 genotypes of tomato (Lycopersicon esculentum, wild relatives and suspected interspecific crosses) were assayed for shoot regeneration from in vitro cultured hypocotyl segments, and approximately one-fourth of the tested genotypes exhibited relatively high differentiation capabilities.
TL;DR: The alkaloid production in the unorganized callus cultures was stimulated by light, and anthraquinones were found in all tissue cultures.
Abstract: Studies were performed on the alkaloid content of leaf and stem callus cultures of CINCHONA PUBESCENS Vahl with respect to the influence of plant growth regulators and light. The same alkaloids were found in the analysed tissues - with some quantitative differences. In general, a medium containing zeatin: 1 microM and 2,4-dichlorophenoxyacetic acid: 1 microM gave a higher alkaloid production than a medium containing benzyladenine: 8.1 microM and 2,4-dichlorophentoxy acetic acid: 4.5 microM. The alkaloid production in the unorganized callus cultures was stimulated by light. Anthraquinones were found in all tissue cultures.
TL;DR: The principal biologically active cytokinin extracted from root tissue of Phaseolus vulgaris L was identified by highperformance liquid chromatography (HPLC) and mass spectrometry as zeatin-Oglucoside as mentioned in this paper.
TL;DR: High frequency plantlet regeneration is obtained by means of in vitro culture of neoformed roots arising from Actinidia chinensis Pl. stamens and the favourable influence of zeatin upon bud initiation from roots is demonstrated.
Abstract: High frequency plantlet regeneration is obtained by means of in vitro culture of neoformed roots arising from Actinidia chinensis Pl. stamens. The favourable influence of zeatin upon bud initiation...
TL;DR: Kinetin and benzylaminopurine (BAP) are the most efficient cytokinins, both in terms of the frequency with which tassels produce normal spikelets and in the number of such spikelets per tassel.
Abstract: Tassels of Zea mays L. (cv. Seneca-60) cultured in a defined liquid medium, produce normal spikelets, especially in the presence of cytokinins. Kinetin and benzylaminopurine (BAP) are the most efficient cytokinins, both in terms of the frequency with which tassels produce normal spikelets and in the number of such spikelets per tassel. Zeatin, zeatin riboside, and 6-(γ,γ-dimethylallylamino)-purine (2iP) are less effective. Other common and individual responses to the cytokinins are noted.
TL;DR: Endogenous levels of cytokinins in an anise cell culture were determined by the use of radioimmunoassay and gas chromatography-mass spectrometry in combination with single-ion monitoring, during proembryonal and embryonal development, with no correlation between different embryonic stages and the endogenous cytokinin level.
Abstract: Endogenous levels of cytokinins in an anise cell culture were determined by the use of radioimmunoassay and gas chromatography-mass spectrometry in combination with single-ion monitoring, during proembryonal and embryonal development. In both cultures the highest cytokinin levels were correlated with logarithmic growth (embryonal: isopentenyladenosine, 4 ng g-1 fresh weight [FW]; isopentenyladenine, 1.4 ng g-1 FW; zeatin, 3.6 ng g-1 FW; proembryonal: isopentenyladenosine, 58.3 ng g-1 FW; isopentenyladenine, 7.9 ng g-1 FW; zeatin 11.1 ng g-1 FW). The proembryonic culture medium but not the embryonic culture medium contained isopentenyladenosine up to 28 pg ml-1 during logarithmic growth. No correlation between different embryonic stages and the endogenous cytokinin level was obvious.
TL;DR: Tissue cultures grown from stem explants of three Actinidia species and a hybrid species rapidly converted N6-isopentenyladenine to zeatin (io6Ade), a potent hydroxylated cytokinin, which was purified using HPLC and identified by its characteristic UV and mass spectra.
TL;DR: Seeds of Olea europaea L. oleaster Hoffm.
Abstract: Seeds of Olea europaea L. ssp. oleaster Hoffm. and Link freed from the sclerous endoearp and incubated in water at 15 or 25°C in darkness or in 12:12 h white light:dark conditions, did not germinate, due to dormancy imposed by the endosperm. Seeds also did not germinate when incubated in abscisic acid, gibberellic acid, kinetin or zeatin in darkness and at cither 15 or 25°C. SAN 9789 |4-chloro-5-(methylamine)-2-(a,a,a-trifluoro-m-tolyl)-3-(2H)-pyridazmone] did not promote germination at 15°C but it did to a 75% level at 25°C. This promoting effect of SAN was counteracted by abscisic acid. Cultures of naked embryos grew equally well in the presence or absence of SAN 9789. 6-Benzylaminopurine promoted whole seed germination to a 15% level.
TL;DR: Comparative studies on the control of root and shoot-bud formation and plant regeneration have been undertaken in discs excised from tubers of potato cultured in vitro and it is concluded that the optimal culture conditions for shoot-Bud formation were quite different from those for root formation.
Abstract: Comparative studies on the control of root and shoot-bud formation and plant regeneration have been undertaken in discs (1 × 6 mm in diameter) excised from tubers of potato (Solanum tuberosum L. cv. Irish Cobbler) cultured in vitro. The results clarified that the optimal culture conditions for shoot-bud formation were quite different from those for root formation and, in conclusion, that (1) shoot-buds were produced when cultured in modified White's medium containing 0.25 M mannitol with 2.3 μM zeatin and 0.57 μM indole-3-acetic acid (IAA) at 20°C under relatively high light irradiation, while (2) roots were readily formed when cultured in modified White's medium containing 29 mM sucrose with 4.7 μM kinetin plus 1.7 μM IAA at 30°C in darkness.
Journal Article•
TL;DR: Cytokinin-like substances were produced in higher amounts by soil isolates than by those isolated from the rhizosphere and mycorrhizosphere, and it is suggested that zeatin andZeatin riboside are likely to be among the cytokinin -like substances detected.
Abstract: Cytokinin-like substances were produced in higher amounts by soil isolates than by those isolated from the rhizosphere and mycorrhizosphere. However more bacterial strains isolated from the rhizosphere and mycorrhizosphere were capable of synthesizing cytokinin-like compounds. A distinct effect of pH on the production of these substances was found. It is suggested that zeatin and zeatin riboside are likely to be among the cytokinin-like substances detected.
TL;DR: Labelled zeatin applied to either the xylem or phloem regions of the stems of developing Phaseolus vulgaris L. plants was transported in a pattern which was in accordance with what appears to be the distribution of endogenous cytokinins in this plant.
TL;DR: Results indicate that several cytokinins inhibit this reaction in microsomal extracts of liquid endosperm from immature wild cucumber seeds, and the basis for the inhibition ofent-kaurene oxidation by cytokinin may be similar to that of ancymidol: interaction with cytochrome P-450.
Abstract: Cytokinins, which have some structural similarities to ancymidol, a plant growth retardant, were tested for their effects on the cell-free oxidation ofent-kaurene. Results indicate that several cytokinins inhibit this reaction in microsomal extracts of liquid endosperm from immature wild cucumber seeds. N6-cyclohexanemethyladenine was the most active (inhibiting 50% of the controlent-kaurene oxidation at 2×10−6 M). N6-isoamyladenine, N6-benzyladenine, N6-(Δ2-isopentenyl)adenine and dihydrozeatin were active at successively higher concentrations. Zeatin, kinetin, adenine, N6-benzyladenosine, and N6-(isopentenyl)adenosine were inactive in this system.
TL;DR: Decreasing the calcium chloride content of the medium for the moss, Pylaisiella selwynii, reduces the number of developed buds obtained in the presence of zeatin, whereas similar changes in magnesium sulfate concentration have no effiect.
Abstract: Decreasing the calcium chloride content of the medium for the moss, Pylaisiella selwynii (Kindb.) Steere and Anderson, reduces the number of developed buds obtained in the presence of zeatin (1 MM), whereas similar changes in magnesium sulfate concentration have no effiect. Cobalt (10 gM), lanthanum (lO gM), zinc (10 MM) and cadmium (0.01 MM) chlorides inhibit zeatin-induced bud formation even in the presence of 680 MM calcium, the normal concentration in the medium. Chlorpromazine (0.1 MM), cyclic adenosine 3',5'-monophosphate (lO0 MM), and glutamate ( l O0 MM) also inhibit zeatin-induced bud initiation. Ethylene glycol-bis(d-aminoethyl ether)N,N,N',N'-tetraacetic acid (l HM), the antibiotic A23187 (100 MM) and octopine (100 MM) each act synergistically with zeatin in promoting bud development and are generally more effective at calcium concentrations of 6.8 MM or less. The combination of either ethylene glycolbis(:-aminoethyl ether)N,N,N',N'-tetraacetic acid, A238 17 or octopine with zeatin plus any of the inhibitory metals or compounds results in more buds than are obtained with zeatin alone and these combinations are more effiective relative to zeatin response at calcium concentrations lower than 6.8 MM. Experiments with Funaria hygrometrica (L.) Sibth. indicate a similar response to calcium, octopine and glutamate. These results appear to be related through changes in
TL;DR: Cytokinin activity was detected in the culture medium of Vinca rosea crown-gall tumour tissue 1 week after subculture, and was detectable even at the end of a 10-week culture period.
Abstract: Cytokinin activity was detected in the culture medium of Vinca rosea (Catharanthus roseus (L.) G. Don) crown-gall tumour tissue 1 week after subculture. Activity increased with time, reaching a plateau at 5-6 weeks. The cytokinin activity from extracts of staled culture medium after 1 and 2 weeks culture cochromatographed with zeatin, zeatin riboside and their dihydro derivatives. An additional slow-moving peak of cytokinin glucoside-like activity was observed from 3 weeks after subculture, and was detectable even at the end of a 10-week culture period. When [U-14C]adenine was supplied to V. rosea crown-gall tissue, analysis of radioactivity remaining in the medium showed incorporation of label into zeatin and zeatin riboside (trans-isomers only) after only 1 h of incubation. Radioactivity in these compounds increased with time; peaking at 8 h, and was still detectable 125 h after incubation. At no time was radioactivity detected in dihydrozeatin, isopentenyladenine or their ribosides. At the end of 125 h incubation, less than 0.2% of radioactivity supplied initially was still present as adenine in the medium. Significant inhibition of tissue growth occurred when it was cultured on medium supplemented with a synthetic or naturally occumng cytokinin.
Journal Article•
TL;DR: Results demons-trate that cotyledon and hypocotyl/eco-potyl of leguminous seedings are ex-cellent starting material for tissue cul-ture, because of their apparent regene-ration capacity.
Abstract: The paper reports that plantletshave been regenerated through embryo-genesis or bud formation in the cultureof hypocotyl and cotyledon explants ofAstragalus sinicus L,but only throughbud formation in cultures of the ecopo-tyl of Phaseolus angularis Wight,thehypocotyl and cotyledon of Sesbaniacannabina(Retz)Persand hypocotylcallus of Cajanus cajan(L)MillspAmong the cytokinins tested,zeatin orits combination with lower concentra-tions of auxin(IAA or NAA)greatlystimulated bud formation in the cul-ture of hypocotyl/ecopotyl and cotyle-don explantsThe results demons-trate that cotyledon and hypocotyl/eco-potyl of leguminous seedings are ex-cellent starting material for tissue cul-ture,because of their apparent regene-ration capacity
TL;DR: Buds are induced only by cytokinins, the largest number being produced with kinetin, followed by benzylaminopurine, bryokinin (2iP) and zeatin, and normal shoot buds were formed but their number was considerably reduced.
Abstract: SUMMARY Protonema of Trematodon brevicalyx remains bud-free on basal medium (Knop's Major and Nitsch's Minor salts). Indoleacetic acid (IAA), gibberellic acid, abscisic acid, chelates, salicylic acid and altered temperature, pH, agar, sucrose levels, light levels and photoperiod do not induce buds but affect gemma initiation and growth rates of protonema. Buds are induced only by cytokinins, the largest number being produced with kinetin, followed by benzylaminopurine, bryokinin (2iP) and zeatin. When varying concentrations of IAA (10-4 to 10-8 M) were added together with the optimum concentration of kinetin (10-5 M), normal shoot buds were formed but their number was considerably reduced.