The control of bud dormancy in potato tubers

Potato (Solanum tuberosum L.) tuber buds normally remain dormant through the growing season until several weeks after harvest. In the cultivar Majestic, this innate dormancy persisted for 9 to 12 weeks in storage at 10° C, but only 3 to 4 weeks when the tubers were stored at 2° C. At certain stages, supplying cytokinins to tubers with innately dormant buds induced sprout growth within 2 d. The growth rate was comparable to that of buds whose innate dormancy had been lost naturally. Cytokinin-treatment did not accelerate the rates of cell division and cell expansion in buds whose innate dormancy had already broken naturally. Gibberellic acid did not induce sprout growth in buds with innate dormancy. We conclude that cytokinins may well be the primary factor in the switch from innate dormancy to the non-dormant state in potato tuber buds, but probably do not control the subsequent sprout growth.Abbreviations tio ⁶ade 6-(4-hydroxy-3-methylbut-trans-2-enyl amino)purine, zeatin - tio⁶ado 6-(4-hydroxy-3-methylbut-trans-2-enyl amino)-9--D-ribofuranosyl purine, zeatin riboside     

Induction of secondary dormancy in Amaranthus caudatus seeds

Nondormant A. caudatus seeds germinated in the darkat temperatures between 20 and 35° but not at 45 °C.Incubation at this temperature for at least 10 h inhibited seedgermination over the temperature range 20 to 35 °C,temperatures previously suitable for germination. Thus incubation at 45°C induced secondary dormancy. Mechanical or chemicalscarification or exposure to pure oxygen caused complete or almost completegermination of dormant seeds although more slowly in comparison to nondormantseeds. Secondary dormant scarified seeds required a lower concentration of ABAthan nondormant seeds to inhibit germination. The high temperature, whichinduced dormancy, 45 °C, caused the seed coat to be partiallyresponsible for secondary dormancy. Involvement of ABA (synthesis orsensitivity) in the induction and/or maintenance of this dormancy should beconsidered.     

Germination in Zostera japonica is determined by cold stratification, tidal elevation and sediment type

The effects of water temperature and bottom sediment type were studied on seed dormancy and germination of Zostera japonica Ascherson & Graebner in mesocosm. To test whether the germination rate is affected by cold stratification, seeds were divided into two groups: those exposed to cold (7 °C) and those left untreated (23–15 °C). Additionally, to mimic tidal variation, we used five tidal depth treatments for germination experiments in mesocosm. In mesocosm tanks, there was a wide range of daily fluctuating temperature at datum line +40 cm (17–25 °C), D.L. +20 cm (15 °C), and D.L. +0 cm (4–7 °C). In contrast, the maximum temperature range at D.L. −20 cm and −40 cm was narrow (5–6 °C). In the no cold stratification group, the maximum germination rates on sandy, muddy sand, and muddy bottom sediment were 3%, 11%, and 3%, respectively. In the cold stratification group (7 °C), the maximum germination rates were 40%, 53%, and 54%, respectively. First germination was observed 36 ± 0 days and 43 ± 6 days after the start of the germination experiment in the cold stratification group and the no cold stratification group, respectively. Bottom sediment type and tidal level did not affect seed germination in the both stratification group. Cold stratification strongly increases germination in all sediment types tested and under varying temperature regimes and at different tidal levels. We also tested whether seed germination is affected by daily fluctuations in temperature (10 °C constant, 15 °C/10 °C, and 20 °C/10 °C were compared) in an indoor incubator. Forty-two days after being sown, the maximum seedling emergence rates in the three groups were 3 ± 5%, 21 ± 7%, and 42 ± 26%, respectively. At 20 °C/10 °C, first germination was observed 11 days after the start of incubation, the germination rate rose sharply after 18 day of incubation, and then it leveled off after 32–42 days of incubation. In the no cold stratification group, seed germination was not observed in any of the three treatments. This finding suggests that the breaking of seed dormancy and germination of Z. japonica seeds are determined strongly by cold temperature and daily fluctuations of temperature, respectively.     

Seed germination and dormancy in the medicinal woodland herbs Collinsonia canadensis L. (Lamiaceae) and Dioscorea villosa L. (Dioscoreaceae)

We used a double germination phenology or “move-along” experiment (sensu Baskin and Baskin, 2003) to characterize seed dormancy in two medicinal woodland herbs, Collinsonia canadensis L. (Lamiaceae) and Dioscorea villosa L. (Dioscoreaceae). Imbibed seeds of both species were moved through the following two sequences of simulated thermoperiods: (a) 30/15 °C→20/10 °C→15/6 °C→5 °C→15/6 °C→20/10 °C→30/15 °C, and (b) 5 °C→15/6 °C→20/10 °C→30/15 °C→20/10 °C→15/6 °C→5 °C. In each sequence, seeds of both species germinated to high rates (>85%) at cool temperatures (15/6 and 20/10 °C) only if seeds were previously exposed to cold temperatures (5 °C). Seeds kept at four control thermoperiods (5, 15/6, 20/10, 30/15 °C) for 30 d showed little or no germination. Seeds of both species, therefore, have physiological dormancy that is broken by 12 weeks of cold (5 °C) stratification. Morphological studies indicated that embryos of C. canadensis have “investing” embryos at maturity (morphological dormancy absent), whereas embryos of D. villosa are undeveloped at maturity (morphological dormancy present). Because warm temperatures are required for embryo growth and cold stratification breaks physiological dormancy, D. villosa seeds have non-deep simple morphophysiological dormancy (MPD). Neither species afterripened in a 6-month dry storage treatment. Cold stratification treatments of 4 and 8 weeks alleviated dormancy in both species but C. canadensis seeds germinated at slower speeds and lower rates compared to seeds given 12 weeks of cold stratification. In their natural habitat, both species disperse seeds in mid- to late autumn and germinate in the spring after cold winter temperatures alleviate endogenous dormancy.     

Dormancy removal of apple seeds by cold stratification is associated with fluctuation in H2O2, NO production and protein carbonylation level

Reactive oxygen (ROS) and nitrogen (RNS) species play a signaling role in seed dormancy alleviation and germination. Their action may be described by the oxidative/nitrosative “window/door”. ROS accumulation in embryos could lead to oxidative modification of protein through carbonylation. Mature apple (Malus domestica Borkh.) seeds are dormant and do not germinate. Their dormancy may be overcome by 70–90 days long cold stratification. The aim of this work was to analyze the relationship between germinability of embryos isolated from cold (5 °C) or warm (25 °C) stratified apple seeds and ROS or nitric oxide (NO) production and accumulation of protein carbonyl groups. A biphasic pattern of variation in H₂O₂ concentration in the embryos during cold stratification was detected. H₂O₂ content increased markedly after 7 days of seeds imbibition at 5 °C. After an additional two months of cold stratification, the H₂O₂ concentration in embryos reached the maximum. NO production by the embryos was low during entire period of stratification, but increased significantly in germination sensu stricto (i.e. phase II of the germination process). The highest content of protein carbonyl groups was detected after 6 weeks of cold stratification treatment. Fluctuation of H₂O₂ and protein carbonylation seems to play a pivotal role in seed dormancy alleviation by cold stratification, while NO appears to be necessary for seed germination.     

A role of microtubules in the polarity of statocytes from roots of Lepidium sativum L.

When roots of Lepidium sativum L. are immersed in a colchicine solution (10^-4 mol l^-1), the cortical microtubules of statocytes are affected such that the dense network ofmicrotubules at the distal cell edges, between the endoplasmic reticulum and the plasma membrane, disappears almost completely, whereas the microtubules, lining the anticlinal cell walls are reduced only to a limited extent. Upon inversion of colchicine-pretreated roots, the distal complex of endoplasmic reticulum sinks into the interior of the statocyte. Germination of seeds in the cold (3–4°C) leads to a retardation of statocyte development; the elaborated system of endoplasmic reticulum is lacking, and only a few microtubules are observable, lining the plasma membrane along the anticlinal cell walls. During an additional 4 h at 24°C, groups of microtubules develop near the plasma membrane in the distal one-third of the statocytes, coaligning with newly synthesized cisternae of the endoplasmic reticulum. It is proposed that, particularly at the distal statocyte pole, microtubules in coordination with cross-bridging structures, act in stabilizing the polar arrangement of the distal endoplasmic reticulum and, in turn, facilitate an integrated function of amyloplasts, endoplasmic reticulum and plasma membrane in graviperception.Abbreviations ER endoplasmic reticulum - MT microtubule     

De novo ABA synthesis and expression of seed dormancy in a gymnosperm: Pseudotsuga menziesii

Seeds of dormant Douglas-fir seeds germinated poorly when they were cultivated at 20–23 °C while isolated embryos germinated fully within two weeks. Seed dormancy was therefore imposed on the embryo by its surrounding structures. This physiological behaviour was well correlated with changes in ABA level during culture. Indeed, the ABA level decreased in isolated embryos while it increased in both embryo and megagametophyte during culture of whole seeds. The origin of this increase was analysed and the different ways by which seed coats could interfere with ABA accumulation are discussed.     

The life-cycle of Apatania fimbriata Pictet in the Breitenbach

The life-cycle of Apatania fimbriata (Pictet, 1843) (Trichoptera: Limnephilidae) was studied in the Breitenbach (Hesse, Federal Republic of Germany) and in the laboratory at 6 °C, 10 °C and 14 °C at 14 h day length. Embryogenesis was mainly temperature dependent in the 4 °C–18 °C range. At a constant 22 °C embryos developed to well-differentiated larvae which did not hatch. In the laboratory experiments, developmental rates increased with increasing temperature (6 °C, 10 °C and 14 °C); larvae went through a dormancy in the third and fourth larval instars; in the field this occurred between November and February. The dormancy synchronized the larval development. Laboratory studies led to the conclusion that the dormancy was not temperature dependent but endogenously determined. The emergence pattern of adults showed a clear diurnal pattern, with a maximum emergence approximately two hours after sunset. A comparison of several years emergence studies showed a decreasing number of females with increasing distance from the spring. A comparison of the dry weight of females between two traps at the stream showed a significantly higher weight from the downstream site. For males no between-site differences were observed.     

A possible mechanism of high temperature dormancy regulation in seeds of Avena sativa L. (cv. Moyencourt)

Embryos of Avena sativa L. (cv. Moyencourt) show no high temperature dormancy. The dormancy is induced by the presence of endosperm-aleurone part of the seed. Germination of isolated embryos at 30°C can be prevented by ABA and the inhibition is reversed by GA. Inhibitors of GA synthesis also inhibit embryo germination. The embryos of dormant and non-dormant seeds vary greatly in their sensitivity to exogenous ABA. High temperature dormancy of the entire seeds can be relieved by low concentrations of ethanol. On the basis of these facts a hypothetic model is proposed showing how interaction between endogenous GA and ABA-like inhibitory substance, may regulate the high temperature dormancy of the seeds.     

Abscisic acid relationships in the chill-related dormancy mechanism in apple seeds

Abscisic acid (ABA) levels in seeds from three cultivars of apple (Malus domestica Borkh.) which have substantially different chilling requirements were investigated by gas chromatography mass-spectrometry selected ion monitoring (GCMS-SIM) during stratification. The ABA content of dormant unchilled seeds was similar in the three cultivars, suggesting no relationship between the chilling requirement of those seeds and their ABA status. That chilling is not related to ABA changes during stratification was confirmed by warm (20°C) and cold (5°C) stratification experiments. ABA content dropped rapidly and nearly identically under both temperature regimes, but only cold stratification promoted germination. The decline in ABA during stratification was due in large part to leaching from the seed coat and nucellar membrane; the ABA content of the embryo remained nearly constant. The radicle in intact seeds stratified at 5°C began growing 20–30 days after the ABA in the seed coat and nucellar membrane had nearly disappeared. Radicle growth did not occur in unchilled seeds, even though ABA had leached from them as well. It is possible that the leaching of ABA from the seed allows certain promotive forces to develop, but if so, these can develop only at chilling temperatures. Studies were also conducted on 2-trans ABA relationships to apple seed dormancy, but no association was evident.Report No. 12, Department of Fruit and Vegetable Science, Cornell University.     

极度濒危植物大果木莲种子的休眠与萌发

大果木莲种子具吸水性,胚未完全发育。新鲜种子25℃下的萌发率仅2％,在30／20℃和20／10℃的条件下30d内分别有27％和36％种子萌发。在20／10℃下,1000mg·L^-1浓度的GA3可以有效打破种子休眠。冷层积120d的种胚生长不显著,大果木莲种子具有条件休眠特性,属于浅度简单型形态生理休眠。种子经冷层积60d的萌发率最高,而后下降,提示其可能有休眠循环现象。     

Does cold stratification level out differences in seed germinability between populations?

Populations of seeds can vary greatly in their dormancy-breaking and germination characteristics. The purpose of this study was to determine if such dormancy differences are levelled out by cold stratification. Seeds of 33 annual weed species, each represented by three populations, were tested in light and darkness 7 weeks after harvest and after two stratification treatments: 18 weeks at 3 °C in the laboratory and 19 weeks outdoors in soil during winter. Cold stratification removed population differences in some species, but in several species such differences became apparent only after stratification. This happened either because dormancy became stronger in weakly dormant seeds (winter annuals) or weaker in strongly dormant seeds (summer annuals). In several species, the light requirement for germination increased after stratification. These results clearly indicate that germination tests performed on fresh seeds from a single population may not adequately predict germination percentages in the field.     

The effect of stratification temperatures on the level of dormancy in primary and secondary dormant seeds of two <Emphasis Type="Italic">Carex</Emphasis> species

The effect of temperature on the level of dormancy of primary and secondary dormant Carex pendula and Carex remota seeds was investigated. Primary dormant and secondary dormant seeds were stratified for 4 weeks at 5, 11, 13, and 15 °C, respectively, and tested for germination at 15/5 °C in light. To obtain secondary dormant seeds, primary dormant seeds were stratified at 5 °C and afterwards at 25 °C for 4 weeks. Germination tests were carried out in water and in 25 μmol KNO₃-solution to examine differences in sensitivity to nitrate between seeds relieved from primary and secondary dormancy. In both species, seeds with primary and with induced secondary dormancy showed no significant differences in germination. The two sedges showed significant differences in the effect of stratification temperatures between primary and secondary dormant seeds. Primary dormant seeds of C. pendula showed high germination (>80%) in nitrate-solution after stratification at all temperatures, while only temperatures of 5, 11, and 13 °C led to higher germination in nitrate-solution in secondary dormant seeds. Germination percentages of primary and of secondary dormant C. pendula seeds in water increased to a higher extent only after stratification at 5 and 11 °C; stratification of 11 °C was more effective in secondary than in primary dormant seeds. The only temperature that relieved primary dormancy in C. remota seeds was 5 °C where germination in water and nitrate-solution was >90%. Germination of secondary dormant seeds was increased by stratification at 11 °C independent of the test solution but higher germination after stratification at 13 °C occurred only in nitrate-solution. The results support the existence of physiological differences in the regulation of primary and secondary dormancy by temperature, and in the reaction of nitrate, at least in C. remota.     

Wintertime changes in the ultrastructure and metabolism of the microsporangiate strobili of the Scotch pine

Terminal buds of Pinus silvestris L. containing microsporangiate strobilus primordia were collected once a month throughout the winter. The electron microscopic studies indicated that in October and December, the cells of the strobili contained a large number of vacuoles, a portion of which was supposedly autophagic, and stacked rough endoplasmic reticulum. By February, the amount of these had decreased, and instead, a large population of dense bodies was visible. Additional phenomena, characteristic at this state, were the occurrences of highly uneven contours of the plasmalemma and of inclusions of various kinds between the plasmalemma and the cell wall. In March, autolysis was visible in a portion of cells outside the sporangia. In the sporangia the ground cytoplasm was thin but the number of organelles was increasing. In the April collections, cell divisions were visible. The amount of protein per dry weight increased during the winter reaching a peak in February. The activity of RNases, having optima of pH 5.0 and pH 7.5, was measured in two successive years. Both series showed a period of high activity during the middle of the winter. The exact timing of this period depended on the year in question. On the basis of these observations, the dormant period of the microsporangiate strobili of the Seotch pine is divided into three sub-periods. It is also suggested that the definition of dormancy of these structures should include a mentioning of alterations in the metabolical machinery of the cells.Abbreviations CH chromosome - CW cell wall - D dictyosome - ER endoplasmic reticulum - L lipid spherule - M mitochondrion - N nucleus - NE nuclear envelope - P plasma membrane - Pp proplastid - RER rough ER - V vacuole     

Microspore development inBrassica napus and the effect of high temperature on division in vivo and in vitro

Summary Brassica napus cv. Topas microspores isolated and cultured near the first pollen mitosis and subjected to a heat treatment develop into haploid embryos at a frequency of about 20%. In order to obtain a greater understanding of the induction process and embryogenesis, transmission electron microscopy was used to study the development of pollen from the mid-uninucleate to the bicellular microspore stage. The effect of 24 h of high temperature (32.5 °C) on microspore development was examined by heat treating microspore cultures or entire plants. Mid-uninucleate microspores contained small vacuoles. Late-uninucleate vacuolate microspores contained a large vacuole. The large vacuole of the vacuolate stage was fragmented into numerous small vacuoles in the late-uninucleate stage. The late-uninucleate stage contained an increased number of ribosomes, a pollen coat covering the exine and a laterally positioned nucleus. Prior to the first pollen mitosis the nucleus of the lateuninucleate microspore appeared to be appressed to the plasma membrane; numerous perinuclear microtubules were observed. Microspores developing into pollen divided asymmetrically to form a large vegetative cell with amyloplasts and a small generative cell without plastids. The cells were separated by a lens-shaped cell wall which later diminished. At the late-bicellular stage the generative cell was observed within the vegetative cell. Starch and lipid reserves were present in the vegetative cell and the rough endoplasmic reticulum and Golgi were abundant. The microspore isolation procedure removed the pollen coat, but did not redistribute or alter the morphology of the organelles. Microspores cultured at 25 °C for 24 h resembled late-bicellular microspores except more starch and a thicker intine were present. A more equal division of microspores occurred during the 24 h heat treatment (32.5 °C) of the entire plant or of cultures. A planar wall separated the cells of the bicellular microspores. Both daughter cells contained plastids and the nuclei were of similar size. Cultured embryogenie microspores contained electron-dense deposits at the plasma membrane/cell wall interface, vesicle-like structures in the cell walls and organelle-free regions in the cytoplasm. The results are related to embryogenesis and a possible mechanism of induction is discussed.Abbreviations B binucleate - LU late uninucleate - LUV late uninucleate vacuolate - M mitotic - MU mid-uninucleate - RER rough endoplasmic reticulum - TEM transmission electron micrograph     

Combinational dormancy in seeds of Sicyos angulatus (Cucurbitaceae,tribe Sicyeae)

Seeds with a water‐impermeable seed coat and a physiologically dormant embryo are classified as having combinational dormancy. Seeds of Sicyos angulatus (burcucumber) have been clearly shown to have a water‐impermeable seed coat (physical dormancy [PY]). The primary aim of the present study was to confirm (or not) that physiological dormancy (PD) is also present in seeds of S. angulatus. The highest germination of scarified fresh (38%) and 3‐month dry‐stored (36%) seeds occurred at 35/20°C. The rate (speed) of germination was faster in scarified dry‐stored seeds than in scarified fresh seeds. Removal of the seed coat, but leaving the membrane surrounding the embryo intact, increased germination of both fresh and dry‐stored seeds to > 85% at 35/20°C. Germination (80–100%) of excised embryos (both seed coat and membrane removed) occurred at 15/6, 25/15 and 35/20°C and reached 95–100% after 4 days of incubation at 25/15 and 35/20°C. Dry storage (after‐ripening) caused an increase in the germination percentage of scarified and of decoated seeds at 25/15°C and in both germination percentage and rate of excised embryos at 15/6°C. Eight weeks of cold stratification resulted in a significant increase in the germination of scarified seeds at 25/15 and 35/20°C and of decoated seeds at 15/6 and 25/15°C. Based on the results of our study and on information reported in the literature, we conclude that seeds of S. angulatus not only have PY, but also non‐deep PD, that is, combinational dormancy (PY + PD).     

Effect of gibberellic Acid and actinomycin d on the formation and distribution of rough endoplasmic reticulum in barley aleurone cells

Analysis of structural changes in barley aleurone cells during germination or following incubation of isolated layers in gibberellic acid with or without actinomycin D revealed extensive development of rough endoplasmic reticulum. Following the assembly of stacked rough endoplasmic reticulum, vesiculation occurred mainly in basal regions of the cell, resulting in a polar distribution of rough endoplasmic reticulum vesicles. It is postulated that these vesicles are involved in protein secretion, because smooth vesicles, derived from the rough endoplasmic reticulum, apparently become appressed to the plasma membrane. The increased α-amylase in the ambient medium and in cell homogenates correlated directly with formation and subsequent vesiculation of the rough endoplasmic reticulum. Furthermore, when cells were treated with actinomycin D and gibberellic acid, α-amylase synthesis was inhibited by 45% and secretion by 63%. These cells were characterized cytologically by large areas of disarrayed segments of fragmented rough endoplasmic reticulum, corresponding to a high intracellular level of α-amylase. In addition, small lipid bodies common to the segmented regions of rough endoplasmic reticulum were surrounded by fine fibrous material, short segments of rough endoplasmic reticulum, and free ribosomes, suggesting that actinomycin D had interfered with development and organization of rough endoplasmic reticulum.     

Characterization of cDNA clones for differentially expressed genes in embryos of dormant and nondormant Avena fatua L. caryopses

The molecular regulation of seed dormancy was investigated using differential display to visualize and isolate cDNAs representing differentially expressed genes during early imbibition of dormant and nondormant Avena fatua L. embryos. Of about 3000 cDNA bands examined, 5 cDNAs hybridized with mRNAs exhibiting dormancy-associated expression patterns during the first 48 h of imbibition, while many more nondormancy-associated cDNAs were observed. Dormancy-associated clone AFD1 hybridized with a 1.5 kb mRNA barely detectable in dry dormant and nondormant embryos that became more abundant in dormant embryos after 24 h of imbibition. Clone AFD2 hybridized with two mRNAs, a 1.3 kb message constitutively expressed in dormant and nondormant embryos and a 0.9 kb message present at higher levels in dormant embryos after 3 h of imbibition. Nondormancy-associated clones AFN1, AFN2 and AFN3 hybridized with 1.5 kb, 1.7 kb and 1.1 kb mRNAs, respectively, that were more abundant in nondormant embryos during imbibition. Expression patterns of some mRNAs in dormant embryos induced to germinate by GA₃ treatment were different than water controls, but were not identical to those observed in nondormant embryos. DNA sequence analysis revealed 76% sequence identity between clone AFN3 and a Citrus sinensis glutathione peroxidase-like cDNA, while significant sequence similarities with known genes were not found for other clones. Southern hybridization analyses showed that all clones represent low (1 to 4) copy number genes.     

The control of bud dormancy in potato tubers. Measurement of the seasonal pattern of changing concentrations of zeatin-cytokinins

A radioimmunoassay, combined with high-performance liquid chromatography, has been used to analyse the zeatin-type cytokinins of potato (Solanum tuberosum L. cv. Majestic) tubers and tuber buds throughout growth and storage. During tuber growth, zeatin riboside was the predominant cytokinin detected in all tissues. Immediately after harvest, the total cytokinin concentration fell dramatically in the storage tissue, largely as a consequence of the disappearance of zeatin riboside. During storage, levels of cytokinins in the storage tissue remained relatively constant, but increased in the tuber buds. In the buds of tubers stored at 2°C there was a 20-to 50-fold increase in total cytokinin over six weeks, coinciding with the natural break of innate dormancy. At 10°C the rise in the level of bud cytokinins was slower, correlating with the longer duration of innate dormancy. Injecting unlabelled cytokinins into tubers in amounts known to induce sprouting gave rise to increases in cytokinin concentrations in the buds of the same order as the increase associated with the natural break of dormancy. Metabolism of injected cytokinins was greater in non-dormant than in dormant tubers. The roles of cytokinin concentration and the sensitivity of the buds to cytokinin in the control of dormancy are discussed.Abbreviations CK cytokinin - FW fresh weight - HPLC high-performance liquid chromatography - RIA radioimmunoassay - tio⁶ade 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-purine=zeatin - tio⁶adeglc⁹ 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9--D-glucopyranosyl purine=zeatin-9-glucoside - tio⁶ado 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9--D-ribofuranosyl purine=zeatin riboside - tio⁶ado-[³H]-diol a radioactive derivative of zeatin riboside, synthesised by periodate-oxidation followed by [³H]NaBH₄-reduction - tio⁶AMP 6-(4-hydroxy-3-methylbut-trans-2-enylamino)-9--D-5-phosphoribofuranosyl purine=zeatin riboside 5-monophosphate - t(ioglc⁴)⁶ade 6-(4-O--D-glucopyranosyl-3-methylbut-trans-2-enylamino)-purine=zeatin-O-glucoside