The Effect of Kinetin on Protein Level of Tobacco Leaf Disks

Sugiuka, Masahiro; Umemura, Keiko; Oota, Yukito

doi:10.1111/j.1399-3054.1962.tb08050.x

Cited by 80 publications

(26 citation statements)

References 16 publications

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“…Experiments with isolated leaf discs of Nicotiana and Xanthium have demonstrated that senescence is retarded by kinetin and this response to a kinin is associated with the maintenance or promotion of RNA and protein synthesis (Wollgiehn, 1961;Osborne, 1962;Sugiura et al, 1962). Another kinin, benzyladenine, is known to be metabolized to its riboside and ribotide in Xanthium leaves (McCalla, Morre and Osborne, 1961) which suggests a possible role for kinins in nucleotide metabolism.…”

Section: Discussionmentioning

confidence: 99%

“…Richmond and Lang (1957) and Mothes, Engelbrecht and Kulajewa (1959) have recorded that the kinin, kinetin, retards protein and chlorophyll loss in detached, unrooted leaves of Xanthium and Nicotiana. More recently, Osborne (1962) and also Sugiura, Umemura and Oota (1962), reported independently that these effects of kinetin are associated with the promotion of RNA synthesis. The presence of an endogenous kinin in the sap of Nicotiana plants has been proposed by Kulajewa [Kulaeva] (1962) since applications of this sap caused retention of chlorophyll in the blades of excised Nicotiana leaves.…”

Section: Introductionmentioning

confidence: 99%

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THE AUXIN, 2,4‐DICHLOROPHENOXYACETIC ACID, AS A REGULATOR OF PROTEIN SYNTHESIS AND SENESCENCE IN DETACHED LEAVES OF PRUNUS

Osborne¹,

Hallaway²

1964

New Phytologist

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SUMMARYExperiments on the hormonal regulation of protein synthesis and senescence in detached leaves of Prunus serrulata are described.Senescence is associated with a fall in the content of total protein in the leaf, a loss of chlorophyll and an increase in the soluble nitrogenous fractions. Auxins such as «-hutyl ester of 2,4-dichlorophenoxyacetic acid (2,4-D) effectively retard these changes when supplied to leaves at particular stages of growth and development. 2,4-D is found to stimulate oxygen uptake in young and mature leaves, compared with controls, but has little effect upon oxygen uptake of autumn leaves, while protein levels are maintained by the auxin in freshly detached autumn leaves but not in younger leaves, unless they have already been detached for precise periods of time and considerable protein loss has already taken place.2,4-D prevents protein loss in autumn leaves by maintaining protein synthesis. The incorporation of [i^C] leucine into protein falls by as much as 60% in 7 days in control halves of leaves, but in halves of the same leaves which have been supplied with 2,4-D, the incorporation of [^^C] leucine into protein is sustained at, or above, the original level.It is proposed that auxins participate in the balance of hormonal factors which regulate the metabolism of protein. They would appear to be essential for maintaining the incorporation of amino acids into protein, and at certain stages of leaf development, they would appear to be limiting for the proper functioning of the processes of protein synthesis.The results are discussed in connection with known effects of environment on the auxin content of leaves, and with effects of auxins and other plant growth regulators on protein and nucleic acid metabolism.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

THE AUXIN, 2,4‐DICHLOROPHENOXYACETIC ACID, AS A REGULATOR OF PROTEIN SYNTHESIS AND SENESCENCE IN DETACHED LEAVES OF PRUNUS

Osborne¹,

Hallaway²

1964

New Phytologist

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“…Sugiura et al (13) found that in detached leaves from Nicotiana species kinetin promoted net nucleic acid and protein synthesis only when internal sugar levels were sufficiently high. Boothby and Wright (4) (10,15).…”

Section: Plant Grovvth and Samplingmentioning

confidence: 99%

Kinetin and Carbohydrate Metabolism in Chinese Cabbage

Berridge¹,

Ralph²

1971

Plant Physiol.

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The effects of kinetin on starch and sugar levels and on 4CO2 and aP-orthophosphate labeling patterns of floated Chinese cabbage (Brassica pekinensis) leaf discs were investigated. Kinetin caused gross starch degradation. Neutral sugars were depressed by 30 to 40% in leaf tissue treated with kinetin for 24 hours. 14CO2 labeling of leaf discs pretreated with kinetin for 24 hours showed increased radioactivity in chloroform-soluble material and most sugar phosphates, and a 35 to 40% decrease in radioactivity in the neutral sugars, glucose, sucrose, and fructose. Incorporation into ATP was increased by 40 % by kinetin. "P-Orthophosphate uptake was inhibited 30 % by kinetin. When corrected for uptake, kinetin stimulated incorporation into chloroform-soluble material but had little effect on other cell fractions. These results indicate that kinetin mobilizes starch reserves and increases the flow of sugars required for the synthesis of lipids and structural materials in floated discs.We have previously shown (2) that cytokinins stimulate expansion of floated Chinese cabbage leaf discs while maintaining the levels of ribosomes and RNA in the discs. We report here effects of kinetin and sucrose on Chinese cabbage leaf disc expansion; on starch, sugar, and sugar phosphate levels; and on fixation and metabolism of "CO2 in floated leaf discs. MATERIALS AND METHODS PLANT GROVVTH AND SAMPLINGChinese cabbage (Brassica pekinensis, var. Wong Bok) plants were grown in a glasshouse at 25 C under natural light. Young rapidly expanding leaves 7 to 11 cm long from 4-to 6-weekold plants were routinely used. Discs (9-mm diameter) were removed from interveinal areas with a cork borer and floated on solutions made up in Vickery's solution (2). Equal numbers of discs from each half-leaf were randomly distributed between Petri dishes, and the dishes were incubated in a light room (600 lumens/sq ft) at 25 C under a 16-hr photoperiod. Following incubation the discs were washed with water, blotted dry, weighed and extracted.The mechanism of action of the plant hormones, cytokinins, is at present unknown. Cytokinins have been shown to modify the incorporation of radioactive precursors into nucleic acids and proteins in excised leaf tissue (11). However, recent more critical studies (8,14) (10,15). STARCH AND SUGAR DETERMINATIONStarch. Leaf discs were ground with 4 ml of TM buffer (0.01 M MgCl2, 0.01 M tris-HCl, pH 7.6). The homogenate was strained through fine cheesecloth. The mortar and cheesecloth were rinsed with 4 ml of TM buffer, and the total extract was centrifuged at 12,000g for 10 min. The pellet was extracted twice with TM buffer containing 2% Triton X-100 (to remove chlorophyll). After centrifugation the resulting pellet was suspended in 2 ml of TM buffer and incubated with pancreatic deoxyribonuclease I (10 ,tg) at 27 C for 25 min. The remaining insoluble material was washed twice with 95% ethanol. Starch in the residue was hydrolyzed with perchloric acid, and the resulting sugars were determined with anthrone (9).Sugars....

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“…A comiparative study was made of the efffects of auxin (a-naphthalene acetic acid), kinetin (6-furfurylaminopurine) and a mixture of auxin and kinetin applied in vivo on synthesis okf RNA and protein and the distribution of such synthesis am'ongst the subcellular fractions of sections of endocarp from Kentucky Wonder pole beans (Phascolus vulgaris, L. Kinetin has a small but significant effect in retarding the rate of degradation df RNA in excised sections of bean endocarp during a 24-h>our period (13). For excised leaves or leaf sections kinetin delays senescence and stimulates synthlesis of nucleic acids and/or protein (5,6,8,17,20), but its site of action has not been elucidated. It has been shown that kinetin gets incorporated unaltered into both RNA and DNA of Lei?nWa miinor (19) and that the effect of kinetin on growuth of cultures of tobacco pith tissue is correlated with its iincorporation into tran.sfer RNA (2).…”

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confidence: 99%