The effect of kinetin on nucleic acids and nucleases of excised barley leaves.

Srivastava, B. I. Sahai; Ware, G. C.

doi:10.1104/pp.40.1.62

Cited by 85 publications

(38 citation statements)

References 9 publications

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“…Similar transient interruption in the course of seniescence may be inferred from data of other reports (16,20). Mothes and Engelbrecht (11 ) have described the directed transport of substrate from the lamina to the petiole of the senescing leaf.…”

Section: Discussionsupporting

confidence: 70%

Effect of the Kinetin-Naphthaleneacetic Acid Interaction Upon Total RNA and Protein in Senescing Detached Leaves

Vonabrams

Pratt

1968

Plant Physiol.

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Abstract. The interaction between kinetin and naphthaleneacetic acid in the regulation of senescence of excised tissue of mature broccoli leaves has been used to examine the extent of synchrony between changes in chlorophyll, RNA, and protein. Kinetin increased the net uptake of 14C-labeled orotic acid and leucine. Naphthaleneacetic acid decreased the effect of kinetin on net uptake after long treatment, but in short-time treatments the auxin increased the effect of kinetin on net uptake. Results of long (24 hr) treatments indicated a general synchrony between the loss of RNA, protein, and chlorophyll. Naphthaleneacetic acid reduced the stabilizing effect of kinetin upon chlorophyll content and upon the content and synthesis of RNA. In short-time experiments, however, RNA content and synthesis were transiently increased by kinetin, and further increased by kinetin plus naphthaleneacetic acid, while chlorophyll content decreased in the presence of kinetin and decreased further in the presence of kinetin pluis naphthaleneacetic acid. Actinomycin-D accelerated the loss of chlorophyll, RNA and protein and strongly depressed the rate of RNA synthesis. In the presence of actinomycin-D the stabilizing effect of kinetin upon RNA was substantially reduced. In contrast, the chlorophyll and protein contents remained higher than in the control. Actinomycin-D did not nullify the basal incorporation of orotic acid into RNA, nor did it negate the effect of kinetin upon incorporation. The failure of synchrony between changes in chlorophyll and RNA does not substantiate the proposal that kinetin regulates senescence by a direct effect upon DNA-dependent RNA synthesis.The senescence of detached leaves is characterized by loss of chlorophyll, associated with declining levels of RNA and protein, and the rate of senescence may be regulated by kinetin or other exogenous growth substances (5,12,21,25 radioactivity, and the total activity was used as an estimate of the net uptake of labeled substrate by the tissue. Radioactivity was determined by drying duplicate aliquots on glass-paper circles and counting in a toluene-fluor mixture in a liquid scintillation spectrometer. Quench correction was calculated from internal standard series prepared for each fraction. In some experiments, net uptake was verified in parallel samples by a combustion method (23). A "corrected incorporation" value was calculated by dividing cpm incorporated by the ratio of the net uptake (total cpm remaining after washing) of the treated sample to the net uptake of the control sample. Sacher (14) has discussed the need for a similar correction.

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Section: Discussionsupporting

confidence: 70%

Effect of the Kinetin-Naphthaleneacetic Acid Interaction Upon Total RNA and Protein in Senescing Detached Leaves

Vonabrams

Pratt

1968

Plant Physiol.

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“…(22). On the other hand, kinetin was reported to suppress the activity of nucleases (17,24). Thus it is also possible that the development of IAA oxidase isoenzymes A5 and A6 was due to a multiple effect of cytokinin on synthesis and degradation of RNA.…”

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confidence: 99%

Cytokinin-controlled Indoleacetic Acid Oxidase Isoenzymes in Tobacco Callus Cultures

Lee¹

1971

Plant Physiol.

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MATERIALS AND METHODSIndoleacetic acid oxidase in tobacco callus tissues (Nicotiana tabacum L., cultivar White Gold) was resolved into seven anionic isoenzymes by polyacrylamide gel disc electrophoresis. Different concentrations of kinetin and zeatin in the presence of indoleacetic acid affected the level of this enzyme, particularly two fast-moving isoenzymes, A5 and A6. The optimal concentration of kinetin was 0.2 gM; increasing concentrations above this level progressively lowered the total activity of indoleacetic acid oxidase and repressed the development of isoenzymes As and A6. Actinomycin D and cycloheximide inhibited the development of these two isoenzymes under the influence of 0.2 Mm kinetin, suggesting a requirement for RNA and protein synthesis.The cytokinin-promoted indoleacetic acid oxidase isoenzymes A5 and A6 increased with time and paralleled the dry weight increase of tobacco callus tissues, but the total activity of indoleacetic acid oxidase per unit dry weight of tobacco callus varied with time depending on the stage of plant growth.Little is known of the effect of cytokinin on indoleacetic acid oxidase in plants. Preparation of Extracts. Five grams of the fresh tissue were extracted in a Potter-Elvehjem tissue homogenizer with 10 ml of phosphate buffer (0.05 M, pH 7.5) containing 0.8 M KCI and 0.05 M sodium ascorbate. The slurry was centrifuged at 20,000g for 10 min, and the residue was reextracted twice with fresh medium and centrifuged. The total volume of the combined extract was 25 ml. A portion of the extract was dialyzed for 22 hr against 4 liters of deionized water, which was changed twice during this period. All operations were done at 2 to 4 C. The dialyzed extract was centrifuged, and the clear supernatant was used as the enzyme source.Electrophoresis. The disc electrophoresis procedure used was basically that of Davis (3). The Buchler analytical polyacrylamide disc electrophoresis apparatus was used. Each tube was 75 mm long and 5 mm in inner diameter. For an effective separation, the gel column was composed of two sections, the upper 10 mm of 4.5% (w/v) polyacrylamide gel and the lower 55 mm of 5.5% polyacrylamide gel. The extract, after mixing with a 60%o (w/v) sucrose solution (2:1), was applied (0.2 ml) to the top of the gel just before electrophoresis. The amount of proteins per gel was from 15 to 75 Ag. The temperature of the buffer in the lower reservoir was kept at 4 C during electrophoresis by circulating cold water through the cooling jacket from a refrigerated water bath. The current applied was 2 ma per gel and the electrophoresis was completed in 1.5 hr. Immediately after the completion of electrophoresis, the gel column was removed from the tube, frozen on Dry Ice, and sliced into 1-mm sections. Each section was extracted with 2 ml of 0.03 M phosphate buffer, pH 6.0, with constant shaking for 20 hr at 4 C. The anionic isoenzymes thus separated were designated as Al to A7.IAA Oxidase Assay. The tubes containing 1 mm gel slices and buffer after 20 hr extrac...

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“…This makes the problem still critical (Beever, 1976).The activity of DNase increases during senescence but work done on this enzyme is very limited (Srivastava and ware, 1965;Simon, 1967;Kumar and Khan, 1984;Meyer and Wagner, 1986). Increase in protease activity is also exhibited during senescence (Anderson and Rowan, 1965;Beevers, 1968;Kar and Mishra, 1977;Peoples and Dalling 1988;Vander Valk and vanloon, 1988).…”

Section: Discussionmentioning

confidence: 99%

“…RNase activity increases during leaf senescence (Bagi and Upadhyaya et al , 1985, Brady, 1988Balnk et al , 1991. But the rise of RNase was not observed in both attached and detached leaves of certain plants (Srivastava and Ware, 1965). The enzyme acid phosphatase is used as a marker of lysosome in animal tissue (Beevers, 1976).…”

Section: Introductionmentioning

confidence: 99%

Study of the exogenous hormonal regulation of leaf senescence in two millets, Setaria italica, l. and Pennisetum typhoides, burm

Mahapatra¹,

Kumar²,

Mohanty³

2016

IJBR

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The present project is aimed at studying the exogenous regulation of leaf senescence in two millets i.e. Setaria italica, L. and Pennisetum typhoides Burm. The present study is confined to the study of excised leaf senescence by using growth regulators as the exogenous agents. Attached leaf study was avoided for the reason that preliminary experiments showed insensitiveness of the leaves of these two millets to growth regulators in the attached condition. In this study three growth regulators were selected, each from three major groups. Benzimidazole (BZI) represented cytokinins and indole acetic acid represented the auxins and GA 3 represented Gibberelic Acid. In the present investigation, a significant negative correlation between RNA loss and RNase activity was found in both S.italica and P.typhoides. This suggests RNase like chlorophyllase responsible for bio-molecular breakdown. DNase activity was stable, it's activity increasing either in the first 72 h or up to the end of the incubation, but DNase activity decreased with time. Thus there was no correlation between the two. Acid phosphatase activity did not show any correlation with the established parameters of senescence, thus in both the plants the activity of the enzyme cannot be treated as an indicator of senescence. Among the two pyrophosphatases, alkaline enzyme showed a parallelism with the changes in chlorophyll and can be used as a reliable indicator of the process. On the other hand acid inorganic phosphatase activity increased during the incubation, but had no significant relation with other senescence related changes, suggesting more investigations to ascertain the role of acid inorganic pyrophosphatase.

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The effect of kinetin on nucleic acids and nucleases of excised barley leaves.

Cited by 85 publications

References 9 publications

Effect of the Kinetin-Naphthaleneacetic Acid Interaction Upon Total RNA and Protein in Senescing Detached Leaves

Effect of the Kinetin-Naphthaleneacetic Acid Interaction Upon Total RNA and Protein in Senescing Detached Leaves

Cytokinin-controlled Indoleacetic Acid Oxidase Isoenzymes in Tobacco Callus Cultures

Study of the exogenous hormonal regulation of leaf senescence in two millets, Setaria italica, l. and Pennisetum typhoides, burm

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