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

Redig, Pascale; Shaul, Orit; Inzé, Dirk; Montagu, Marc Van; Onckelen, Harry Van

doi:10.1016/0014-5793(96)00728-4

Cited by 147 publications

(94 citation statements)

References 38 publications

(39 reference statements)

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“…JA has been reported to change the ratio between cytokinin ribosides and free bases and to decrease the level of zeatin in potato (Solanum tuberosum; Dermastia et al, 1994). In BY-2 cells, zeatin levels peak sharply before G2/M transition (Redig et al, 1996), and its exogenous supply can rescue G2 arrest caused by the inhibition of cytokinin production (Laureys et al, 1998). However, a block of G2/M transition caused by JA could not be recovered by zeatin treatment (data not shown).…”

Section: Discussionmentioning

confidence: 82%

“…However, the activity of phosphatase cdc25, which activates cyclindependent kinase (CDK) by the removal of a phosphate group from a Tyr moiety in the ATP-binding loop, has also been shown to be cytokinin dependent (Zhang et al, 1996). Redig et al (1996) demonstrated that the zeatin level fluctuates in synchronized tobacco BY-2 cells, peaking at late S and before G2/M transition. When zeatin production was blocked, mitotic activity ceased and could only be restored by application of exogenous zeatin (Laureys et al, 1998), suggesting that cytokinins are essential not only for the initiation of the cell cycle but also for the progression through it.…”

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confidence: 99%

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Differential Effect of Jasmonic Acid and Abscisic Acid on Cell Cycle Progression in Tobacco BY-2 Cells

et al. 2002

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Environmental stress affects plant growth and development. Several plant hormones, such as salicylic acid, abscisic acid (ABA), jasmonic acid (JA), and ethylene play a crucial role in altering plant morphology in response to stress. Developmental regulation often has the cell cycle machinery among its targets. We analyzed the effect of JA and ABA on cell cycle progression in synchronized tobacco (Nicotiana tabacum) BY-2 cells. Both compounds were found to prevent DNA replication, keeping the cells in the G1 stage, when applied just before the G1/S transition. However, ABA did not have any effect on subsequent phases of the cell cycle when applied at a later stage, whereas JA effectively prevented mitosis on application during DNA synthesis. This demonstrates that JA treatment can freeze synchronized BY-2 cells in both the G1 and G2 stages of the cell cycle. Jasmonate administered after the S-phase was less effective in decreasing the mitotic index, suggesting that cell sensitivity toward JA is dependent on the cell cycle phase. In cultures detained in the G2-phase, we observed a reduced histone H1 kinase activity of kinases associated with the p13 sucl protein.

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Section: Discussionmentioning

confidence: 82%

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confidence: 99%

Differential Effect of Jasmonic Acid and Abscisic Acid on Cell Cycle Progression in Tobacco BY-2 Cells

et al. 2002

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“…This nuclear labeling observed with anti-zeatin antibody is intriguing in light of the observations made by Redig et al (1996b). By using a synchronized cytokinin autotrophic cell culture (BY2) (Nagata et al, 1992), they found that only zeatin was present during the whole-cell cycle, with a short, transient accumulation of this cytokinin type at the end of the S phase and during the M phase.…”

Section: Discussionmentioning

confidence: 87%

Dynamics of Cytokinins in Apical Shoot Meristems of a Day-Neutral Tobacco during Floral Transition and Flower Formation1

et al. 1999

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This study considered cytokinin distribution in tobacco (Nicotiana tabacum L.) shoot apices in distinct phases of development using immunocytochemistry and quantitative tandem mass spectrometry. In contrast to vegetative apices and flower buds, we detected no free cytokinin bases (zeatin, dihydrozeatin, or isopentenyladenine) in prefloral transition apices. We also observed a 3-fold decrease in the content of cytokinin ribosides (zeatin riboside, dihydrozeatin riboside, and isopentenyladenosine) during this transition phase. The group concluded that organ formation (e.g. leaves and flowers) is characterized by enhanced cytokinin content, in contrast to the very low endogenous cytokinin levels found in prefloral transition apices, which showed no organogenesis. The immunocytochemical analyses revealed a differing intracellular localization of the cytokinin bases. Dihydrozeatin and isopentenyladenine were mainly cytoplasmic and perinuclear, whereas zeatin showed a clear-cut nuclear labeling. To our knowledge, this is the first time that this phenomenon has been reported. Cytokinins do not seem to act as positive effectors in the prefloral transition phase in tobacco shoot apices. Furthermore, the differences in distribution at the cellular level may be indicative of a specific physiological role of zeatin in nuclear processes.

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“…The reduced meristem activity seen in the triple mutant roots seems to be a consequence of a delay in the G 2 3M phase, as demonstrated by FACS experiments. Interestingly, a sharp increase in the levels of zeatin, zeatin riboside, and zeatin riboside-5Ј-monophosphate was reported in tobacco cell cultures at the G 2 3M phase transition (34).…”

Section: Discussionmentioning

confidence: 96%

In planta functions of the Arabidopsis cytokinin receptor family

Higuchi

Pischke

Mähönen

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

617

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Since their discovery as cell-division factors in plant tissue culture about five decades ago, cytokinins have been hypothesized to play a central role in the regulation of cell division and differentiation in plants. To test this hypothesis in planta, we isolated Arabidopsis plants lacking one, two, or three of the genes encoding a subfamily of histidine kinases (CRE1, AHK2, and AHK3) that function as cytokinin receptors. Seeds were obtained for homozygous plants containing mutations in all seven genotypes, namely single, double, and triple mutants, and the responses of germinated seedlings in various cytokinin assays were compared. Both redundant and specific functions for the three different cytokinin receptors were observed. Plants carrying mutations in all three genes did not show cytokinin responses, including inhibition of root elongation, inhibition of root formation, cell proliferation in and greening of calli, and induction of cytokinin primary-response genes. The triple mutants were small and infertile, with a reduction in meristem size and activity, yet they possessed basic organs: roots, stems, and leaves. These results confirm that cytokinins are a pivotal class of plant growth regulators but provide no evidence that cytokinins are required for the processes of gametogenesis and embryogenesis.S ince the discovery of kinetin in 1956 as a degradation product of DNA that promotes cell division in plants (1), a considerable amount of biochemical, physiological, and, most recently, genetic research has focused on elucidating the diverse roles that cytokinins play in plant growth and development. Perturbations of cytokinin levels in plants via over-expression of bacterial cytokinin synthesis genes (2-4), recovery of mutant plants with a higher-than-normal cytokinin content (5), and characterization of loss-of-function mutants of the cytokinin receptor CYTOKININ RESPONSE 1 (CRE1) (6-9) have implicated cytokinins in a wide variety of processes, including cell division, organ formation and regeneration, senescence, apical dominance, vascular development, response to pathogens, and nutrient mobility. These numerous roles for cytokinins, coupled with the failure of mutant screens to yield plants with nondetectable cytokinin levels, led to the longstanding belief that cytokinins are essential for plant growth and development.Plants respond to cytokinin through a multistep phosphorelay system, consisting of sensor histidine kinase (HK) proteins, histidine phosphotransfer (HPt) proteins, and effector response regulator (RR) proteins. Over-expression and loss-of-function analyses of particular HK, HPt, and RR proteins in Arabidopsis (8-13), combined with transient expression assays in protoplasts (14), have led to a model for cytokinin signaling (for a review, see refs. 15 and 16), beginning with perception of cytokinins by HK proteins.The Arabidopsis genome encodes six nonethylene receptor HKs: CRE1͞WOL͞AHK4, AHK2, AHK3, AtHK1, CKI1, and CKI2͞AHK5. Among them, CRE1, Arabidopsis HK2 (AHK2), and Arabidopsis HK3 (A...

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

Cited by 147 publications

References 38 publications

Differential Effect of Jasmonic Acid and Abscisic Acid on Cell Cycle Progression in Tobacco BY-2 Cells

Differential Effect of Jasmonic Acid and Abscisic Acid on Cell Cycle Progression in Tobacco BY-2 Cells

Dynamics of Cytokinins in Apical Shoot Meristems of a Day-Neutral Tobacco during Floral Transition and Flower Formation1

In planta functions of the Arabidopsis cytokinin receptor family

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