Polyribosome Formation in Relation to Cytokinin-induced Cell Division in Suspension Cultures of <i>Glycine max</i> [L.] Merr.

Fosket, Donald E.; Volk, Marva J.; Goldsmith, Marian R.

doi:10.1104/pp.60.4.554

Cited by 46 publications

(16 citation statements)

References 32 publications

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“…Our observation that 2,4-D (1 mg/l) added to pear cells after 6 days in the aging medium fails to induce cell division and protein synthesis is further indication that cytokinin synthesis might be suppressed. This hypothesis is supported by the observations of Maab and Klambt (21) (12).…”

Section: Discussionsupporting

confidence: 81%

Senescence of Pear Fruit Cells Cultured in a Continuously Renewed, Auxin-deprived Medium

Pech¹,

Romani²

1979

Plant Physiol.

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Auxins and cytokinins support cell division in tissue and ceH cultures. In cytokinin-independent pear (Pyrus communis) cels, omission of 2,4di-chlorophenoxyacetic acid (2,4-D) from the medium for two successive transfers leads to rapid cel Iysis, unless the osmolarity is raised to 0.4 molar with mannitol. Use of this system (nutrients plus mannitol minus 2,4-D) for the study of cel senescence was explored both in batch culture and in a system designed to permit medium renewal without withdrawal of live cels.In Before transferring into aging medium the cells were grown for 12 days in the standard medium in absence of 2,4-D at an initial cell density higher than 5 x I05 cells/ml. Prior to transfer, the cells were allowed to settle and were then washed twice with aging medium.Culture in Batch Conditions. Three-liter flasks containing 0.8 liter of aging medium were inoculated with 0.2 liter of cells prepared as described above. The methods for aeration, shaking, and sampling were the same as those for the continuous system described in Figure 1.Culture with Continuously Renewed Medium. The objective was to renew the medium continuously without removing live cells. A schematic diagram of the system is shown in Figure 1.A 2.

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Section: Discussionsupporting

confidence: 81%

Senescence of Pear Fruit Cells Cultured in a Continuously Renewed, Auxin-deprived Medium

Pech¹,

Romani²

1979

Plant Physiol.

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“…As far as we are aware, the present study is the first in which 16 Functional assays have suggested the involvement of cytokinins in the passage through several restriction points of the plant cell cycle. Cytokinins were found to be necessary for the entry of tobacco mesophyll protoplasts into S phase [10] and for the G2/M transition of tobacco and Glycine max suspension cultures [9,11]. Crowell and Salaz [33] have shown that the growth of tobacco BY-2 cells is inhibited by low concentrations of lovastatin, which inhibits the isoprenoid pathway that leads to the biosynthesis of the cytokinin side chain.…”

Section: Discussionmentioning

confidence: 99%

“…Cytokinins and auxins can interact both synergistically and antagonistically; for example, both are required to stimulate cell division in cultured tobacco pith tissues [7], but oppose each other in the control of shoot and root initiation in tissue cultures and in the maintenance of apical dominance [8]. Based on functional assays, cytokinins were suggested to be involved in the passage through several restriction points of the plant cell cycle [9][10][11], There is also evidence for the involvement of other plant hormones, such as abscisic acid [12], gibberellins [13], ethylene [14], and polyamines [15] in the regulation of cell division. Although the effects of phytohormones on plant growth have been studied extensively, not much is known about fluctuations in the levels of endogenous hormones during the cell cycle.…”

Section: Introductionmentioning

confidence: 99%

Levels of endogenous cytokinins, indole‐3‐acetic acid and abscisic acid during the cell cycle of synchronized tobacco BY‐2 cells

Redig¹,

et al. 1996

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Correlation between cell cycle progression and endogenous levels of plant hormones was studied in synchronized tobacco BY-2 cell suspension cultures. Sixteen different cytokinins, indole-3-acetic acid (IAA) and abscisic acid (ABA) were extracted using solid-phase anion exchange chromatography in combination with immunoaffinity purification, and quantified by mass spectrometry. No significant correlation could be identified for IAA and ABA. In contrast, there were sharp peaks in the levels of specific cytokinins (zeatin-and dihydrozeatin-type) at the end of the S phase and during mitosis. The levels of other cytokinins analyzed, including zeatins N-and O-glucosides, remained low, suggesting that the increased amounts of their corresponding non-glucosylated form resulted from de novo synthesis. These f'mdings suggest that zeatin-and dihydrozeatintype cytokinins might play a specific regulatory role in the progression of the plant cell cycle. One hypothesis to explain cytokinin action is based on a specific interaction with kinases that regulate cell cycle progression, as has been recently shown for the cytokinin analogue olomoucine.

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“…In addition, we know that newly synthesized proteins in culture are very different from the proteins of mesophyll cells, as their _u K patterns can be distinguished by monodimensional electrophoresis (5 (6,9), or for auxin and cytokinin (19). In fact, the observed modifications of enzyme activity often occur long after hormone application, frequently in high, nonphysiological concentrations.…”

Section: -D Protein Pattern In Protoplastsmentioning

confidence: 99%

Hormonal Control of Mitotic Development in Tobacco Protoplasts

Meyer¹,

Chartier²

1981

Plant Physiol.

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Two-dimensional separation of proteins newly synthesized by tobacco mesophyli protoplasts cultivated in vitro allows us to detect, reproducibly, 257 spots. The pattern is extremely stable throughout the three days of culture, the intensity of only 24 spots varying during this time. The absence of cytokinin (N-benzyladenine) in the culture medium prohibits entry into S phase but does not modify the pattern, indicating that none of the observed proteins is specifically synthesized in S, G2, or M phases. The presence of 2,4dichlorophenoxyacetic acid is necessary for the mitotic development of protoplasts. It induces the appearance of one protein, increases the level of another, and reduces that of eight others. All proteins sensitive to auxin belong to the group of proteins the levels of which vary during culture.The isolation ofmesophyll protoplasts from their tissue of origin frees them from the influences which maintained the cells in a differentiated state. Protoplasts in culture do not retain the characteristics of the cells from which they originate: they lose photosynthetic activity, but regain mitotic activity and synthesize a cell wall. Although the disappearance ofphotosynthetic activity occurs regardless of the culture medium, both the reformation of the cell wall and the entry into mitosis do take place in the presence of auxin and cytokinin. We have previously shown (4, 14) that if auxin is absent from the medium, mitotic development does not begin, whereas in the absence of cytokinin this development starts but later stops just before S-phase. The study of this experimental system is thus likely to provide information on the modes of action of auxin and cytokinin, as well as on the development of the mitotic program in a plant cell.The results presented here concern the study of newly synthesized proteins in protoplasts cultivated in complete medium or in medium deficient in auxin or cytokinin. To obtain the best resolution currently available, we compared the patterns obtained by two-dimensional separation of proteins: electrofocusing followed by electrophoresis under denaturing conditions (16, 18).MATERIALS AND METHODS Preparation and Culture of Protoplasts. Tobacco mesophyll protoplasts (Nicotiana tabacum var. Maryland) were prepared and cultivated as described previously in medium WO.6 (12,13) Preparation of Samples. After labeling, protoplasts from one culture dish were collected by centrifugation. Total protein was obtained by lysis of protoplast pellets in 100 pl of a solution containing 9.5 M urea, 2% LKB ampholines (pH 3-10), 5% ,Bmercaptoethanol, and 0.2% SDS. This extract can be frozen and stored at -70°C. Just before electrofocusing, the extract was mixed with two volumes of a solution containing 9.5 M urea, 2% Nonidet P40, 2% LKB ampholines (pH 3.5-10), and 5%8-mercaptoethanol and centrifuged 10 min in Eppendorf tubes. In some experiments "buffer-soluble" proteins were obtained by vortexing protoplast pellets for 30 s in 50 pl of 100 mm Tris-HCl, 10 mM EDTA (pH 8.0). To the sup...

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Polyribosome Formation in Relation to Cytokinin-induced Cell Division in Suspension Cultures of Glycine max [L.] Merr.

Cited by 46 publications

References 32 publications

Senescence of Pear Fruit Cells Cultured in a Continuously Renewed, Auxin-deprived Medium

Senescence of Pear Fruit Cells Cultured in a Continuously Renewed, Auxin-deprived Medium

Levels of endogenous cytokinins, indole‐3‐acetic acid and abscisic acid during the cell cycle of synchronized tobacco BY‐2 cells

Hormonal Control of Mitotic Development in Tobacco Protoplasts

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