Synthesis of DNA in excised watermelon cotyledons grown in water and benzyladenine

Galli, Maria Grazia

doi:10.1007/bf00402853

Cited by 15 publications

(8 citation statements)

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“…Correspondence to: H. Teramoto; FAX: 81 (75)7534122 1980a; Thomas et al 1980;Haru et al 1982;Galli 1984). However, how these changes lead to expansion growth remains poorly understood.…”

Section: Introductionmentioning

confidence: 96%

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Isolation of a cDNA clone for a cytokinin-repressed gene in excised cucumber cotyledons

Teramoto

Momotani

Takeba

et al. 1994

Planta

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Rapid changes in gene expression were studied during incubation of cucumber (Cucumis sativus L.) cotyledons with cytokinins in darkness. Complementary-DNA clones for mRNAs whose levels decreased within 4 h of treatment with N6-benzyladenine (BA) were isolated by differential hybridization. One of them (CR9) was sequenced. It is 588 bp long, and would encode a protein consisting of 137 amino-acid residues and having a molecular mass of 15 kDa. The sequence shows a high homology with a light-induced gene from rice. Northern blot analysis of the CR9 transcript showed the level of the mRNA (0.7 kb) to decrease tenfold within 4 h of BA treatment, i.e. well before BA-induced cotyledon expansion was observed. The repression became greater with increasing concentration of BA (10(-8)-10(-5) M). The expression of the CR9 gene was repressed specifically by cytokinins (BA, isopentenyladenine and t-zeatin), but not by adenine or 2,4-dichlorophenoxyacetic acid (auxin). The results are discussed in relation to the primary action of cytokinin.

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“…Correspondence to: H. Teramoto; FAX: 81 (75)7534122 1980a; Thomas et al 1980;Haru et al 1982;Galli 1984). However, how these changes lead to expansion growth remains poorly understood.…”

Section: Introductionmentioning

confidence: 96%

“…Although these observations suggest the importance of RNA synthesis in BA-induced changes, cytokinin-induced cotyledon expansion is less sensitive to inhibitors of RNA synthesis than inhibitors of protein synthesis (Naito et al 1980b). Galli (1984) emphasized the importance of DNA synthesis in BA-induced growth of watermelon cotyledons.…”

Section: Introductionmentioning

confidence: 99%

Isolation of a cDNA clone for a cytokinin-repressed gene in excised cucumber cotyledons

Teramoto

Momotani

Takeba

et al. 1994

Planta

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“…(9,11,12), water uptake (14), increase in fresh weight, and the development of cell organelles (7,12). This wide range of responses is accompanied by an increment ofDNA synthesis (8), induction ofproteins, or enzymes synthesis (9,12). One of the enzyme activities significantly stimulated by the hormone is HPR2 (12).…”

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confidence: 99%

Cytokinin-Modulated Gene Expression in Excised Pumpkin Cotyledons

Chen

Leisner²

1985

Plant Physiol.

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Comparison of two-dimensional polyacrylamide gel electrophoretic maps of proteins isolated from benzyladenine-treated and untreated pumpkin (Cucurbita pepo L. cv Halloween) cotyledons showed that the expression of certain proteins is enhanced, induced, or suppressed by the cytokinin treatment. The amount of poly(A)' mRNA isolated from cotyledons incubated with 10' molar benzyladenine for five days was about four-fold over the water-incubated control. The activity of hydroxypyruvate reductase prepared from purified cotyledonous microbodies and analyzed by native gel electrophoresis is proportionally enhanced by sequentially higher concentrations (10' to 101 molar) of benzyladenine. (9,11,12), water uptake (14), increase in fresh weight, and the development of cell organelles (7,12). This wide range of responses is accompanied by an increment ofDNA synthesis (8), induction ofproteins, or enzymes synthesis (9,12). One of the enzyme activities significantly stimulated by the hormone is HPR2 (12). This enzyme catalyzes the conversion ofhydroxypyruvate to glycerate in microbodies, and is involved in the glycolate pathway (16).Despite an abundance of knowledge about the physiological responses of cotyledons to cytokinin treatment, there is no concrete information on the questions of (a) whether the effects of cytokinin on gene expression are exerted by induction, stimulation, and/or suppression of specific protein syntheses, and (b) if the influence of cytokinin on protein or enzyme synthesis is primarily at the pretranslational or posttranslational level.In the present study, we have utilized two-dimensional PAGE to determine if cytokinin modifies the spectrum of polypeptides synthesized during cytokinin-induced cell expansion ofpumpkin cotyledons. We Cotyledon Preparation. Pumpkin seeds of approximately the same size were imbibed for 16 h with running tap water, and surface sterilized for 10 min with 0.5% NaOCl. The seeds were thoroughly rinsed with sterile distilled H20 and were sown on distilled H20-moistened Whatman No. 1 filter papers contained in Petri dishes under aseptic conditions. These Petri dishes were placed in darkness at room temperature (25°C) for 7 d. Cotyledons were then excised and cultured under aseptic conditions for various times in the dark on filter papers in Petri dishes. The dishes contained 10 ml distilled H20, 0.2 mg/ml penicillin G, with or without BA.Preparation of Microbody HPR. The preparation of pumpkin cotyledon microbodies was adapted from a method for spinach microbody preparation described by Huang et al. (10) and modified by Chang and Huang (3) with the exception that the homogenate was filtered through three layers of cheesecloth instead of Nitex cloth. The microbodies were purified by a 30 to 60% (w/v) linear sucrose gradient. Sucrose gradient-purified microbodies were dialyzed against 10 mm Tris-HCI (pH 7.5) overnight to release proteins from microbodies. The dialysate was centrifuged at 100,000g for 1 h, and the supernatant protein solution containing HPR was reduce...

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“…Divers auteurs ont décrit l'effet des CKs sur cc système en termes de modifications quantitatives de la synthèse des protéines (pour référence, voir Axelos, 1985) ou des acides nucléiques : synthèse du DNA (Galli, 1984), des RNA totaux (Mikulovich ct coll. 1978 ;Klyachko ct coll., 1979 ;Naito ct coll., 1980 ;Kulacva, 1981) -les réponses à des concentrations de l'ordre de lOO JlM incluent l'accroissement de masse fraîche, le catabolisme des lipides, la formation de racines adventives, l'activation d'enzymes mitochondriales (cytochrome C oxydase, fumarase).…”

Section: Iii-controle Par Les Cytokinines De La Syntiiese De Proteinunclassified

Marqueurs moléculaires de l'action des cytokinines sur la multiplication cellulaire et sur la différenciation

Serve¹,

Suty²,

Renaudin³

1988

Bulletin de la Société Botanique de France. Actualités Botaniqu

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Résumé.-Une revue des résultats concernant l'action des cytokinines sur la multiplication cellulaire, sur la différenciation plastidiale et sur le développement d'organes excisés, montre que cette action s'accompagne de l'expression ou de la disparition de marqueurs protéiques définis. Deux classes de marqueurs ont été identifiés : d'une part des protéines, plastidiales ou cytoplasmiques, contrôlées par le phytochrome ; d'autre part certaines protéines de réponse aux agressions (PR). Ces résultats sont discutés en référence au rôle des cytokinines dans les processus de différenciation.Summary.-Results reporting molecular markers of cytokinin activity on cel\ division, plastid diflerentiation, and development of excised organs are reviewed. So far, two classes of cytokinin markers have been identified : the first class consists of phytochrome-controlled proteins ; the second class is composed of PA proteins. These results are discussed in reference to cytokinin activity on differentiation processes. PR proteins.

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Synthesis of DNA in excised watermelon cotyledons grown in water and benzyladenine

Cited by 15 publications

References 21 publications

Isolation of a cDNA clone for a cytokinin-repressed gene in excised cucumber cotyledons

Isolation of a cDNA clone for a cytokinin-repressed gene in excised cucumber cotyledons

Cytokinin-Modulated Gene Expression in Excised Pumpkin Cotyledons

Marqueurs moléculaires de l'action des cytokinines sur la multiplication cellulaire et sur la différenciation

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