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  • 1
    Online Resource
    Online Resource
    Verbundprojekt: INNOX, Teilprojekt 1: Systematische Charakterisierung metaboler Prozesse in den Knollen und deren Abhängigkeit von Sauerstoff sowie Entwicklung einfacher Testsytem für Biomarker. Teilprojekt: Metabolismus der Kohlenhydratspeicherung ; Schlussbericht ; Förderungszeitraum: 01.02.2008 - 31.7.2009 (2009)
    Großbeeren
    Details Availability
    Keywords: Forschungsbericht
    Type of Medium: Online Resource
    Pages: Online-Ressource (14 S., 255 KB)
    URL: https://edocs.tib.eu/files/e01fb11/665499582.pdf
    URL: https://doi.org/10.2314/GBV:665499582
    URL: https://edocs.tib.eu/files/e01fb11/665499582l.pdf
    DOI: 10.2314/GBV:665499582
    Language: German
    Note: Förderkennzeichen BMBF 0313813G. - Verbund-Nr. 01048906 , Systemvoraussetzungen: Acrobat reader.
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  • 2
    Online Resource
    Online Resource
    Gabi-SysSeed, Teilprojekt C : Abschlussbericht zum Verbundvorhaben GABI-SYS-SEED, Teilprojekt C ; Förderungszeitraum: 01.07.2007 bis 30.06.2010 (verlängert bis 31.12.2010) (2011)
    Potsdam
    Details Availability
    Keywords: Forschungsbericht
    Type of Medium: Online Resource
    Pages: Online-Ressource (PDF-Datei: 5 S., 36 KB)
    URL: https://edocs.tib.eu/files/e01fb12/726583731.pdf
    URL: https://doi.org/10.2314/GBV:726583731
    URL: https://edocs.tib.eu/files/e01fb12/726583731l.pdf
    DOI: 10.2314/GBV:726583731
    Language: German
    Note: Auch als gedr. Ausg. vorh. - Unterschiede zwischen dem gedruckten Dokument und der elektronischen Ressource können nicht ausgeschlossen werden , Förderkennzeichen BMBF 0315044C. - Verbund-Nr. 01057631. - Dt. Berichtsbl. u.d.T.: Gabi-FUTURE-Verbundvorhaben: "Integrierte Modellierung des Primärstoffwechsels des sich entwickelnden Gersten-Endosperms unter dem Einfluss hormonaler Regulierung (GABI-SysSEED)", Teilprojekt C: Kompartiment-spezifische Metabolit- und Flussanalysen , Systemvoraussetzungen: Acrobat reader.
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  • 3
    Electronic Resource
    Electronic Resource
    Cold-induced repression of the rice anther-specific cell wall invertase gene OSINV4 is correlated with sucrose accumulation and pollen sterility (2005)
    Oxford, UK : Blackwell Science Ltd
    Plant, cell & environment 28 (2005), S. 0 
    Details
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Low temperatures during rice (Oryza sativa L.) pollen development cause pollen sterility and decreased grain yield. We show that the time of highest sensitivity to cold coincides with the time of peak tapetal activity: the transition of the tetrad to early uni-nucleate stage (young microspore, YM stage). Low temperatures at this stage of pollen development result in an accumulation of sucrose in the anthers, accompanied by decreased activity of cell wall bound acid invertase and depletion of starch in mature pollen grains. Expression analysis of two cell wall (OSINV1, 4) and one vacuolar (OSINV2) acid invertase genes showed that OSINV4 is anther-specific and down-regulated by cold treatment. OSINV4 is transiently expressed in the tapetum cell layer at the YM stage, and later from the early binucleate stage in the maturing microspores. The down-regulation of OSINV4 expression in the tapetum at YM may cause a disruption in hexose production and starch formation in the pollen grains. In a cold-tolerant cultivar, OSINV4 expression was not reduced by cold; sucrose did not accumulate in the anthers and starch formation in the pollen grains was not affected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-3040.2005.01390.x
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  • 4
    Electronic Resource
    Electronic Resource
    Starch content and yield increase as a result of altering adenylate pools in transgenic plants (2002)
    [s.l.] : Nature Publishing Group
    Nature biotechnology 20 (2002), S. 1256-1260 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] Starch represents the most important carbohydrate used for food and feed purposes. With the aim of increasing starch content, we decided to modulate the adenylate pool by changing the activity of the plastidial adenylate kinase in transgenic potato plants. As a result, we observed a substantial ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt760
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  • 5
    Electronic Resource
    Electronic Resource
    Regulation of sucrose and starch metabolism in potato tubers in response to short-term water deficit (1997)
    Springer
    Planta 201 (1997), S. 502-518 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Adenosine 5′-diphosphoglucose ; Starch synthesis ; Solanum (carbon metabolism ; tuber) ;  Sucrose-phosphate synthase ; Sucrose metabolism (futile cycle) ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. To investigate the effect of water stress on carbon metabolism in growing potato tubers (Solanum tuberosum L.), freshly cut and washed discs were incubated in a range of mannitol concentrations corresponding to external water potential between 0 and −1.2 MPa. (i) Incorporation of [14C]glucose into starch was inhibited in water-stressed discs, and labeling of sucrose was increased. High glucose overrode the changes at low water stress (up to −0.5 MPa) but not at high water stress. (ii) Although [14C]sucrose uptake increased in water-stressed discs, less of the absorbed [14C]sucrose was metabolised. (iii) Analysis of the sucrose content of the discs confirmed that increasing water deficit leads to a switch, from net sucrose degradation to net sucrose synthesis. (iv) In parallel incubations containing identical concentrations of sugars but differing in which sugar was labeled, degradation of [14C]sucrose and labeling of sucrose from [14C]glucose and fructose was found at each mannitol concentration. This shows that there is a cycle of sucrose degradation and resynthesis in these tuber discs. Increasing the extent of water stress changed the relation between sucrose breakdown and sucrose synthesis, in favour of synthesis. (v) Analysis of metabolites showed a biphasic response to increasing water deficit. Moderate water stress (0–200 mM mannitol) led to a decrease of the phosphorylated intermediates, especially 3-phosphoglycerate (3PGA). The decrease of metabolites at moderate water stress was not seen when high concentrations of glucose were supplied to the discs. More extreme water stress (300–500 mM mannitol) was accompanied by an accumulation of metabolites at low and high glucose. (vi) Moderate water stress led to an activation of sucrose phosphate synthase (SPS) in discs, and in intact tubers. The stimulation involved a change in the kinetic properties of SPS, and was blocked␣by protein phosphatase inhibitors. (vii) The amount of ADP-glucose (ADPGlc) decreased when discs were incubated on 100 or 200 mM mannitol. There was a strong correlation between the in vivo levels of ADPGlc and 3PGA when discs were subjected to moderate water stress, and when the sugar supply was varied. (viii) The level of ADPGlc increased and starch synthesis was further inhibited when discs were incubated in 300–500 mM mannitol. (ix) It is proposed that moderate water stress leads to an activation of SPS and stimulates sucrose synthesis. The resulting decline of 3PGA leads to a partial inhibition of ADP-glucose pyrophosphorylase and starch synthesis. More-extreme water stress leads to a further alteration of partitioning, because it inhibits the activities of one or more of the enzymes involved in the terminal reactions of starch synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050095
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  • 6
    Electronic Resource
    Electronic Resource
    Overexpression of pyrophosphatase leads to increased sucrose degradation and starch synthesis, increased activities of enzymes for sucrose-starch interconversions, and increased levels of nucleotides in growing potato tubers (1998)
    Springer
    Planta 205 (1998), S. 428-437 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Nucleotide ; Pyrophosphatase ; Solanum (carbohydrate metabolism) ; Starch ; Sucrose ; Tuber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Overexpression of inorganic pyrophosphatase (PPase) from Escherichia coli in the cytosol of plants (ppa1 plants) leads to a decrease of inorganic pyrophosphate (PPi; U. Sonnewald, 1992, Plant J 2: 571–581). The consequences for sucrose-starch interconversions have now been studied in growing potato (Solanum tuberosum L. cv. Desirée) tubers. Sucrose is degraded via sucrose synthase and UDP-glucose pyrophosphorylase in growing tubers, and it was expected that the low PPi in the ppa1 transformants would restrict the mobilisation of sucrose and conversion to starch. Over-expression of PPase resulted in an accumulation of sucrose and UDP-glucose, and decreased concentrations of hexose phosphates and glycerate-3-phosphate in growing ppa1 tubers. Unexpectedly, the rate of degradation of [14C] sucrose was increased by up to 30%, the rate of starch synthesis was increased, and the starch content was increased by 20–30% in ppa1 tubers compared to wild-type tubers. Reasons for this unexpectedly efficient conversion of sucrose to starch in the ppa1 tubers were investigated. (i) The transformed tubers contained increased activities of several enzymes required for sucrose-starch interconversions including two- to threefold more sucrose synthase and 60% more ADP-glucose pyrophosphorylase. They also contained 30–100% increased activities of several glycolytic enzymes and amylase, increased protein, and unaltered or slightly decreased starch phosphorylase, acid invertase and mannosidase. (ii) The transformants contained higher pools of uridine nucleotides. As a result, although the UDP-glucose pool is increased two- to threefold, this does not lead to a decrease of UTP or UDP. (iii) The transformants contained twofold larger pools of ATP and ADP, and ADP-glucose was increased by up to threefold. In stored ppa1 tubers, there were no changes in the activities of glycolytic enzymes, and nucleotides did not increase. It is concluded that in growing tubers PPi has a wider significance than just being an energy donor for specific reactions in the cytosol. Increased rates of PPi hydrolysis also affect general aspects of cell activity including the levels of nucleotides and protein. Possible ways in which PPi hydrolysis could affect these processes are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050340
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  • 7
    Electronic Resource
    Electronic Resource
    Orotate leads to a specific increase in uridine nucleotide levels and a stimulation of sucrose degradation and starch synthesis in discs from growing potato tubers (1999)
    Springer
    Planta 209 (1999), S. 314-323 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Nucleotide ; Orotate ; Solanum (tubers) ; Starch ; Sucrose ; Uridine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Freshly cut discs from growing potato tubers were incubated for 3 h with 10 mM orotate or 10 mM uridine. Control discs incubated without precursors showed a 30–40% decrease of uridine nucleotides, but not of adenine nucleotides. Orotate- and uridine-feeding led to a 1.5- to 2-fold increase in the levels of uridine nucleotides compared with control discs, and a 15–30% increase compared with the original values in intact tubers, but did not alter the levels of adenine nucleotides. Between 70–80% of the uridine nucleotides were present as UDPglucose, 15–25% as UTP, and 2–3% as UDP. The increase of uridine nucleotides involved a similar relative increase of UDPglucose, UTP and UDP. It was accompanied by a slight stimulation of the rate of [14C]sucrose uptake, a 2-fold stimulation of the rate at which the [14C]sucrose was subsequently metabolised, a small increase in the levels of hexose phosphates, glycerate-3-phospate and ADPglucose, and a 30% shift in the allocation of the metabolised label in favour of starch synthesis, resulting in a 2.4-fold stimulation of the rate of starch synthesis. Orotate led to a similar increase of uridine nucleotide levels in the presence of [14C]glucose, but did not significantly alter the rate of glucose uptake and metabolism to starch, nor did it increase the rate of sucrose resynthesis. The levels of uridine nucleotides were high in tubers on 6 to 10-week-old potato plants, and declined in tubers on 12 to 15-week-old plants. Comparison with the effect of the uridine nucleotide level in discs shows that the high levels of uridine nucleotides in tubers on young plants will play an important role in determining the rate at which sucrose can be converted to starch, and that the level of uridine nucleotides is probably co-limiting for sucrose-starch conversions in tubers on older plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050638
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  • 8
    Electronic Resource
    Electronic Resource
    Contribution of adenosine 5′-diphosphoglucose pyrophosphorylase to the control of starch synthesis is decreased by water stress in growing potato tubers (1999)
    Springer
    Planta 209 (1999), S. 338-345 
    Details
    ISSN: 1432-2048
    Keywords: Key words: Adenosine 5′-diphosphoglucose pyrophosphorylase ; Cell wall ; Control analysis ; Solanum (starch synthesis) ; Starch ; Water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Water stress stimulates sucrose synthesis and inhibits starch and cell-wall synthesis in tissue slices of growing potato (Solanum tuberosum L. cv. Desirée) tubers. Based on the analysis of fluxes and metabolites, Geigenberger et al. (1997, Planta 201: 502–518) proposed that water deficits up to −0.72 MPa stimulate sucrose synthesis, leading to decreased starch synthesis as a result of the resulting decline of phosphorylated metabolite levels, whereas more-severe water deficits directly inhibit the use of ADP-glucose. Potato plants with decreased expression of adenosine 5′-diphosphoglucose pyrophosphorylase (AGPase) have been used to test the prediction that the contribution of AGPase to the control of starch synthesis should decrease in severely water-stressed tuber material. Freshly cut slices from wild-type and antisense tubers were incubated at a range of mannitol concentrations (20, 300 and 500 mM) and the metabolism of [14C]glucose was analysed. A 86–97% reduction of AGPase activity led to a major but non-stoichiometric inhibition of starch accumulation in intact growing tubers attached to the plant (40–85%), and an inhibition of starch synthesis in non-stressed tuber slices incubated in 20 mM mannitol (60–80%). The inhibition of starch synthesis was accompanied by a 2- to 8-fold increase in the levels of sugars in intact tubers and a 2- to 3-fold stimulation of sucrose synthesis in tuber slices, whereas respiration and cell-wall synthesis were not significantly affected. The strong impact of AGPase on carbon partitioning in non-stressed tubers and tuber slices was retained in slices subjected to moderate water deficit (300 mM mannitol, corresponding to −0.72 MPa). In discs incubated in 500 mM mannitol (corresponding to −1.2 MPa) this response was modified. A 80–97% reduction of AGPase resulted in only a 0–40% inhibition of starch synthesis. Further, the water stress-induced stimulation of sucrose synthesis was abolished in the transformants. The results provide direct evidence that the contribution of AGPase to the control of starch synthesis can be modified by environmental factors, leading to a lower degree of control during severe water deficits. There was also a dramatic decrease in the labelling of cell-wall components in wild-type tuber slices incubated with 300 or 500 mM mannitol. The water stress-induced inhibition of cell-wall synthesis occurred independently of AGPase expression and the accompanying changes in starch and sucrose metabolism, indicating a direct inhibition of cell-wall synthesis in response to water stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004250050641
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  • 9
    Electronic Resource
    Electronic Resource
    Sucrose synthase catalyses a readily reversible reaction in vivo in developing potato tubers and other plant tissues (1993)
    Springer
    Planta 189 (1993), S. 329-339 
    Details
    ISSN: 1432-2048
    Keywords: Chenopodium ; Cycle (futile) ; Ricinus ; Solanum (sucrose metabolism) ; Sucrose synthase ; Transport (sucrose)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Experiments were carried out to investigate whether sucrose synthase (Susy) catalyses a readily reversible reaction in vivo in potato (Solanum tuberosum L.) tubers, Ricinus communis L. cotyledons, and heterotrophic Chenopodium rubrum L. cell-suspension cultures. (i) The contents of sucrose, fructose, UDP and UDP-glucose were measured and the mass-action ratio compared with the theoretical equilibrium constant. In all three tissues the values were similar. (ii) Evidence for rapid turnover of label in the sucrose pool was obtained in pulse-chase experiments with potato discs and with intact tubers attached to the plant. The unidirectional rates of sucrose synthesis and degradation were considerably higher than the net flux through the sucrose pool in the tubers. (iii) Labelling of the glucosyl and fructosyl moieties of sucrose from [14C]glucose in the presence of unlabelled fructose provided evidence that Susy contributes to the movement of label into sucrose. Methods for estimating the contribution of sucrose-phosphate synthase and Susy are presented and it is shown that their relative contribution varies. For example, the contribution of Susy is high in developing tubers and is negligible in harvested tubers which contain low Susy activity. (iv) The absolute values of the forward (v+1) and backward (v−1) reaction direction of Susy are calculated from the kinetic labelling data. The estimated values of v+1 and v−1 are comparable, and much higher than the net flux through the sucrose pool. (v) The estimated concentrations of the substrates and products of Susy in tubers are comparable to the published K m values for potato-tuber Susy. (vi) It is concluded that Susy catalyses a readily reversible reaction in vivo and the relevance of this conclusion is discussed with respect to the regulation of sucrose breakdown and the role of Susy in phloem unloading.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194429
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  • 10
    Electronic Resource
    Electronic Resource
    Regulation of carbon partitioning between sucrose and nitrogen assimilation in cotyledons of germinating Ricinus communis L. seedlings (1991)
    Springer
    Planta 185 (1991), S. 563-568 
    Details
    ISSN: 1432-2048
    Keywords: Fructose-2,6-bisphosphate ; Nitrogen metabolism ; Ricinus ; Sucrose synth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The interactions between carbon and nitrogen metabolism in cotyledons of germinating Ricinus communis L. seedlings were investigated. The endosperm was removed for 6-d-old seedlings and their cotyledons were supplied with 50 mM glucose and mM potassium phosphate without a nitrogen source, or supplemented with 10 mM glutamine or 5 mM NH4Cl. [U14C] Glucose labelling patterns were used to investigate the effect of fluxes. Addition of glutamine or NH4Cl led to a 3.5- to 5-fold increase of labelling in amino acids (most of which were exported) and increased 14CO2 release. Glutamine also led to a stimulation of glucose uptake, sucrose synthesis and export. Measurements of metabolites showed that glutamine or NH4Cl led to a decrease of a-ketoglutarate, pyruvate, phosphoenolpyruvate, glycerate-2-phosphate and glycerate-3-phosphate, a small increase of triose-phosphate and fructose-1,6-bisphosphate, a small decrease of hexose-phosphate (in the case of glutamine), and an increase of UDP glucose. In both treatments, fructose-2,6-bisphosphate doubled, and inorganic pyrophosphate decreased slightly. Similar results were obtained in detached cotyledons, except that glutamine did not alter the rate of glucose uptake or sucrose synthesis. The increased rate of sucrose synthesis after supplying glutamine to intact seedlings is ascribed to an increased rate of sucrose export from the cotyledons due to enhanced water flow in the phloem, brought about by loading of glutamine. The doubling of the rate of glycolysis after adding glutamine or NH4Cl in intact seedlings or excised cotyledons is ascribed to activation of the terminal enzymes in glycolysis, pyruvate kinase and phosphoenolpyruvate carboxylase. The resulting decrease of phosphoenolpyruvate and glycerate-3-phosphate leads to activation of phosphofructokinase. It also relieves inhibition of fructose-6-phosphate,2-kinase, leading to increased fructose-2,6-bisphosphate and activation of pyrophosphate; fructose-6-phosphate phosphotransferase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202967
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