Biological Effects of Cytokinin Antagonists 7-(Pentylamino) and 7-(Benzylamino)-3-Methylpyrazolo(4,3-<i>d</i>)Pyrimidines on Suspension-cultured Tobacco Cells

Gregorini, Giovanna; Laloue, Michel

doi:10.1104/pp.65.2.363

Cited by 18 publications

(3 citation statements)

References 6 publications

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“…Abnormalities of the mitotic apparatus induced by ANCYT1 treatment could result from its inhibitory effect on CDKs and probably other related kinases that have functions during mitosis. The results are also in good agreement with the findings of Gregorini and Laloue (47), who previously demonstrated that in both cytokinin-requiring and cytokinin-autonomous tobacco cell suspension culture, only dividing cells are sensitive to the cytotoxic effects of ANCYT1.…”

Section: Discussionsupporting

confidence: 81%

Classical Anticytokinins Do Not Interact with Cytokinin Receptors but Inhibit Cyclin-dependent Kinases

Spíchal

Kryštof

Paprskářová

et al. 2007

Journal of Biological Chemistry

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Cytokinins are a class of plant hormones that regulate the cell cycle and diverse developmental and physiological processes. Several compounds have been identified that antagonize the effects of cytokinins. Based on structural similarities and competitive inhibition, it has been assumed that these anticytokinins act through a common cellular target, namely the cytokinin receptor. Here, we examined directly the possibility that various representative classical anticytokinins inhibit the Arabidopsis cytokinin receptors CRE1/AHK4 (cytokinin response 1/Arabidopsis histidine kinase 4) and AHK3 (Arabidopsis histidine kinase 3). We show that pyrrolo Cytokinins are plant hormones that play essential roles in the regulation of various aspects of plant growth and development (1). They include a variety of chemicals with different degrees of structural similarity, some of which occur naturally in plants, and others that are known only as synthetic compounds. The natural cytokinins are adenine derivatives that can be classified according to the nature of their N 6 -side chain as either isoprenoid (zeatin) or aromatic (benzyladenine) cytokinins.Cytokinins are key regulators of the plant cell cycle, and the induction of cell division is considered diagnostic for this class of plant hormones. The molecular basis of this activity is only partially understood and may differ in different cell types. Cytokinins have been found to control tyrosine dephosphorylation and activation of p34 cdc2 -like H1 histone kinase (2), as well as the transcriptional activation of cyclin D3 (3). Some of the many physiological and developmental processes that are controlled by cytokinin, such as the formation and activity of shoot apical meristems, floral development, the breaking of bud dormancy, and seed germination (4 -8), are at least in part functionally linked to cell cycle control.Recently, several cytokinin receptors were identified in Arabidopsis (9 -12) and Zea mays (13). To date, three cytokinin receptors have been identified in Arabidopsis, AHK2, 4 AHK3, and CRE1/AHK4. All are membrane-located sensor histidine kinases with a predicted extracellular ligand-binding domain and cytoplasmic His kinase and receiver domains. It has been shown that the cytokinin signal is transmitted by a multistep phospho-relay system through a complex form of the two-component signaling pathway that has long been known in prokaryotes and lower eukaryotes. Among higher eukaryotes, the two-component signaling pathway is only found in plants (reviewed by Refs. 14 -17).

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Section: Discussionsupporting

confidence: 81%

Classical Anticytokinins Do Not Interact with Cytokinin Receptors but Inhibit Cyclin-dependent Kinases

Spíchal

Kryštof

Paprskářová

et al. 2007

Journal of Biological Chemistry

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“…RD 21, which is ineffective in most biological assays (23), inhibits the alternative pathway more strongly than kinetin. Moreover, 7 PMP, an anticytokinin (9), is the most powerful inhibitor of the cyanideresistant electron transfer. Finally, it should be mentioned that zeatin, a naturally occurring cytokinin, has almost no effect on the alternative pathway (18,19).…”

Section: Discussionmentioning

confidence: 99%

Inhibition by Adenine Derivatives of the Cyanide-Insensitive Electron Transport Pathway of Plant Mitochondria

Dizengremel¹,

Chauveau²,

Roussaux³

1982

Plant Physiol.

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The effect of benzylaminopurine was studied on cyanide-resistant mnitochondria isolated from aged slices of potato tuber (Solnum tuberosum L.var. Bintje). Benzylaminopurine specifically acted on the cyanide-resistant alternative pathway. In the case of succinate oxidation, it mimicked the action of salicylhydroxamic acid and restored a good oxidative phosphorylation. Kinetic analyses showed that inhibitions by benzylaminopurine, salicylhydroxamic acid, and disulfiram occurred at mutually exclusive sites on the alternative pathway. Cyanide-resistant malate oxidation was only partially inhibited by benzylaminopurine and this inhibition occurred for low concentrations of this compound. On the other hand, the oxidation of exogenous NADH remained unaffected.The effects of several adenine derivatives with or without cytokinin activity and that of a purine analog with anticytokinin activity were also studied. The variation in effectiveness to inhibit cyanide-resistant electron transport was: benzylaminopurine and 7-pentylamino-3-methylpyrazolo (4,3 d) pyrimidine (anticytokinin) > y-y'dimethyl-allyl-adenine > 6-benzoylamino-9-benzylpurine > kinetin > adenine. No correlation was observed between the ability to inhibit the alternative pathway and the biological activity of these compounds. Liposolubility appeared as a major factor for potential inhibitory effect on the alternative pathway.Aging of potato tuber slices is known to bring about both a rise in tissue respiration and the appearance of cyanide-resistance (1 1, 15, 28). Mitochondria isolated from aged potato slices are characterized by the presence of a functional cyanide-resistant alternative pathway sensitive to SHAM' (5, 6).The process of aging is often compared to a breaking of dormancy resulting in the enhancement of cellular metabolism (1, 7, 13). As cytokinins are known to stimulate many cellular events, this observation suggests that these compounds might be involved in this process. However, the addition of cytokinins to the aging medium for potato slices prevents the increase in the rates of respiration and phosphate absorption (12, 21). Moreover, several results indicate that cytokinins can be inhibitors of cell respiration (3,18,20). Very likely, the site for such an effect is located in the mitochondria (18,19). The proposed site would allow inhibition of both the alternative pathway and the internal NADH dehydrogenase (19).This paper describes the effects of BA on the alternative electron transport pathway in mitochondria from aged potato tuber slices. The relations between BA and known inhibitors of the alternative ' Abbreviations: SHAM, salicylhydroxamic acid; BA, benzylaminopurine; DMAA, dimethyl-allyl-adenine; RD 21, 6-benzoylamino-9-benzylpurine; 7 PMP, 7-pentylamino-3-methylpyrazolo (4,3 d) pyrimidine; DMSO, dimethylsulfoxide. pathway (SHAM, disulfiram) were also investigated. Finally, in order to more precisely define the mode of action of BA, some other compounds, chemically related to BA, were used to establish a possible structure-...

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“…According to the model of Mohr and Schopfer [17], the light response and the cytokinin response are the results of independent series of events . After other experimental results [3,4,13] it was suggested that the light effect(s) and the cytokinin effect(s) might interact : in favour of this hypothesis it was mentioned previously that PAMPP (7-(pentylamino)-3-methylpyrazolo (4,3-d-pyrimidine), a well known competitive anticytokinin [10,20] inhibited the stimulating effect of white light on amaranthin synthesis as well as the cytokinin response [3] .…”

Section: Introductionmentioning

confidence: 99%

Use of 5,6-dichloro-l-?-D-ribofuranosylbenzimidazole to distinguish light stimulation from cytokinin stimulation of amaranthin synthesis in Amaranthus tricolor

Bianco-Colomas¹,

Péaud‐Lenoël²,

Bulard³

1988

Plant Growth Regul

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In Amaranthus tricolor seedlings, amaranthin synthesis can be induced by cytokinins and (or) by light . It was found that 5,6-dichloro-l-fl-D-ribofuranosylbenzimidazole (DRB) was a specific inhibitor of the cytokinin response whereas the light response was unchanged . DRB also inhibited the negative response of pigment production to an anticytokinin, 7-(pentylamino)-3-methylpyrazolo(4,3-d) pyrimidine (PAMPP) .DRB can be considered as a specific inhibitor of the physiological responses to cytokinins . The evolution of the inhibition percentage versus cytokinin or anticytokinin concentration shows that DRB is not a `competitor' of cytokinins .The experiments suggest that cytokinins or anticytokinins act as modulators of a fundamental light activated reaction of amaranthin synthesis .Resume . Chez les plantules d'Amaranthus tricolor, la synthese d'amarantine peut titre induite par les cytokinines et (ou) par la lumiere . Le 5,6-dichloro-l-f-D-ribofuranosylbenzimidazole (DRB) inhibe de fagon specifique la reponse aux cytokinines alors qu'il est sans effet sur l'induction photochimique . Ce compose s'oppose aussi a I'effet inhibiteur d'une anticytokinine la 7-(pentylamino)-3-methylpyrazolo(4,3-d) pyrimidine (PAMPP) .Le DRB peut titre considers comme un inhibiteur specifique des reponses physiologiques aux cytokinines . L'evolution du pourcentage d'inhibition en fonction de la concentration en cytokinine ou en anticytokinine montre que le DRB West pas un inhibiteur competitif des cytokinines.Les experiences suggerent que cytokinines ou anticytokinines agissent en modulant une reaction fondamentale de la synthese d'amarantine contrSlse par la lumiere.

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Biological Effects of Cytokinin Antagonists 7-(Pentylamino) and 7-(Benzylamino)-3-Methylpyrazolo(4,3-d)Pyrimidines on Suspension-cultured Tobacco Cells

Cited by 18 publications

References 6 publications

Classical Anticytokinins Do Not Interact with Cytokinin Receptors but Inhibit Cyclin-dependent Kinases

Classical Anticytokinins Do Not Interact with Cytokinin Receptors but Inhibit Cyclin-dependent Kinases

Inhibition by Adenine Derivatives of the Cyanide-Insensitive Electron Transport Pathway of Plant Mitochondria

Use of 5,6-dichloro-l-?-D-ribofuranosylbenzimidazole to distinguish light stimulation from cytokinin stimulation of amaranthin synthesis in Amaranthus tricolor

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