The Role of Cytokinins in the Development and Metabolism of Barley Leaves III. The Effect on the RNA Metabolism in Various Cell Compartments During Senescence

Legocka, Jolanta; Szweykowska, A.

doi:10.1016/s0044-328x(81)80208-5

Cited by 13 publications

(6 citation statements)

References 44 publications

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“…As the amount of free amino acids in leaves rise after detachment (Thomas 1978, Malik 1982, the increases in the incorporation of radioactivity cannot be attributed to a rise in the specific radioactivity of the precursors in the assays of protein synthesis. The rise in the activity of protein synthesis is apparently in contrast with the simultaneous degradation of chloroplast RNA, Legocka and Szweykowska (1981) did not observe the rapid decrease of rRNA but they incubated whole detached leaves not leaf segments as used in the present study. Although the possibility of rRNA degradation during our extractions cannot entirely be excluded, this possibility seems remote.…”

Section: Discussioncontrasting

confidence: 54%

Protein synthesis by chloroplasts during the senescence of barley leaves

García¹,

Martı́n²,

Sabater³

1983

Physiologia Plantarum

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Chloroplasts were isolated from senescent leaf segments of barley (Hordeum vulgare L. var. Mozoncillo) and assayed for protein synthesis. Protein synthesis activity of the chloroplasts greatly increased after 10–20 h of incubation of leaf segments in the dark in spite of an intense degradation of chloroplast rRNA. The rise in the activity of protein synthesis was more pronounced when kinetin was present in the incubation medium. However, as deduced from SDS‐polyacrylamide gel electrophoresis of the products, different proteins were synthesized under the two conditions of incubation of the leaf segments. The activity of protein synthesis of the chloroplasts decreased during the first hours of incubation of the leaf segments in the light. Cutting and incubation in the dark of the leaf segments enhanced the synthesis of a few proteins also formed by chloroplasts in attached senescing leaves. Hormone and senescence treatments changed the type and the rate of the protein synthesized by chloroplasts, which suggests that hormones may control senescence through a modulation of the protein synthesized by the chloroplasts.

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Section: Discussioncontrasting

confidence: 54%

Protein synthesis by chloroplasts during the senescence of barley leaves

García¹,

Martı́n²,

Sabater³

1983

Physiologia Plantarum

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“…In light of the confirmed role of TGase in animal cell apoptosis and only limited information on the role of this enzyme in leaf senescence, we decided to investigate the activity of ChlTGases and the fate of chloroplast-associated polyamines in barley leaves. We chose a model process that we routinely use for senescence-related studies in which senescence in barley is induced by incubation in the dark (Jackowski 1996 ; Legocka and Szweykowska 1981 ; Żelisko and Jackowski 2004 ).…”

Section: Introductionmentioning

confidence: 99%

Dark-induced senescence of barley leaves involves activation of plastid transglutaminases

et al. 2015

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Transglutaminases (E.C. 2.3.2.13) catalyze the post-translational modification of proteins by establishing ε-(γ-glutamyl) lysine isopeptide bonds and by the covalent conjugation of polyamines to endo-glutamyl residues of proteins. In light of the confirmed role of transglutaminases in animal cell apoptosis and only limited information on the role of these enzymes in plant senescence, we decided to investigate the activity of chloroplast transglutaminases (ChlTGases) and the fate of chloroplast-associated polyamines in Hordeum vulgare L. ‘Nagrad’ leaves, where the senescence process was induced by darkness (day 0) and continued until chloroplast degradation (day 12). Using an anti-TGase antibody, we detected on a subcellular level, the ChlTGases that were associated with destacked/degraded thylakoid membranes, and beginning on day 5, were also found in the stroma. Colorimetric and radiometric assays revealed during senescence an increase in ChlTGases enzymatic activity. The MS/MS identification of plastid proteins conjugated with exogenous polyamines had shown that the ChlTGases are engaged in the post-translational modification of proteins involved in photosystem organization, stress response, and oxidation processes. We also computationally identified the cDNA of Hv-Png1-like, a barley homologue of the Arabidopsis AtPng1 gene. Its mRNA level was raised from days 3 to 10, indicating that transcriptional regulation controls the activity of barley ChlTGases. Together, the presented results deepen our knowledge of the mechanisms of the events happened in dark-induced senescence of barley leaves that might be activation of plastid transglutaminases.Electronic supplementary materialThe online version of this article (doi:10.1007/s00726-014-1912-y) contains supplementary material, which is available to authorized users.

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“…Cytokinins prevent chloroplast degradation by retarding both the breakdown of chlorophyll and the decay of the thylakoid system in senescing leaves. They also lower the activity of proteolytic enzymes and promote protein synthesis in detached barley leaves senescing in the dark ( Legocka and Szweykowska, 1981 , 1983 ). The delay of senescence by cytokinins occurs mainly at the transcriptional level, by inhibiting the expression of senescence-related genes ( Lim et al, 2007 ).…”

Section: Discussionmentioning

confidence: 99%

From Accumulation to Degradation: Reprogramming Polyamine Metabolism Facilitates Dark-Induced Senescence in Barley Leaf Cells

et al. 2016

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The aim of this study was to analyze whether polyamine (PA) metabolism is involved in dark-induced Hordeum vulgare L. ‘Nagrad’ leaf senescence. In the cell, the titer of PAs is relatively constant and is carefully controlled. Senescence-dependent increases in the titer of the free PAs putrescine, spermidine, and spermine occurred when the process was induced, accompanied by the formation of putrescine conjugates. The addition of the anti-senescing agent cytokinin, which delays senescence, to dark-incubated leaves slowed the senescence-dependent PA accumulation. A feature of the senescence process was initial accumulation of PAs at the beginning of the process and their subsequent decrease during the later stages. Indeed, the process was accompanied by both enhanced expression of PA biosynthesis and catabolism genes and an increase in the activity of enzymes involved in the two metabolic pathways. To confirm whether the capacity of the plant to control senescence might be linked to PA, chlorophyll fluorescence parameters, and leaf nitrogen status in senescing barley leaves were measured after PA catabolism inhibition and exogenously applied γ-aminobutyric acid (GABA). The results obtained by blocking putrescine oxidation showed that the senescence process was accelerated. However, when the inhibitor was applied together with GABA, senescence continued without disruption. On the other hand, inhibition of spermidine and spermine oxidation delayed the process. It could be concluded that in dark-induced leaf senescence, the initial accumulation of PAs leads to facilitating their catabolism. Putrescine supports senescence through GABA production and spermidine/spermine supports senescence-dependent degradation processes, is verified by H2O2 generation.

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The Role of Cytokinins in the Development and Metabolism of Barley Leaves III. The Effect on the RNA Metabolism in Various Cell Compartments During Senescence

Cited by 13 publications

References 44 publications

Protein synthesis by chloroplasts during the senescence of barley leaves

Protein synthesis by chloroplasts during the senescence of barley leaves

Dark-induced senescence of barley leaves involves activation of plastid transglutaminases

From Accumulation to Degradation: Reprogramming Polyamine Metabolism Facilitates Dark-Induced Senescence in Barley Leaf Cells

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