When growing potato tubers are detached from their mother plant there is a rapid inhibition of starch synthesis, involving inhibition of ADP-glucose pyrophosphorylase

Geigenberger, Peter; Merlo, Lucia; Reimholz, Ralph; Stitt, Mark

doi:10.1007/bf02411552

Cited by 68 publications

(76 citation statements)

References 35 publications

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“…The estimated concentrations for ATP in the plastid and in the cytosol were 0.49 (4.9 mm) and 0.2 mm, respectively, and for ADP 0.24 mm (2.4 mm) and 0.018 mm (Table I), respectively. The ADP-Glc content in potato tubers is very low; in our experiment, we measured 3.6 Ϯ 0.1 nmol g fresh weight Ϫ1 , which is in agreement with previous studies (Geigenberger et al, 1994;Farré et al, 2000). We could only detect ADP-Glc in the fraction enriched for amyloplasts (data not shown) and therefore were not able to calculate the exact metabolite distribution.…”

Section: Adenine and Uridine Nucleotides Show Different Partitioning supporting

confidence: 93%

“…The different pools of 3-P-glycerate, cytosolic and plastidial, may change independently as they have been shown to do in leaves (Gerhardt et al, 1987). This could explain why correlations between 3-P-glycerate and starch synthesis have only been shown in some cases (Hajirezaei et al, 1994;Geigenberger et al, 1997;Preiss, 1997;Farré et al, 2001), and not in others (Geigenberger et al, 1994;Geiger et al, 1998;Trethewey et al, 1998Trethewey et al, , 1999Fernie et al, 2001).…”

Section: Hexose Phosphates and Glycolytic Intermediates Are Distributmentioning

confidence: 98%

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Analysis of the Compartmentation of Glycolytic Intermediates, Nucleotides, Sugars, Organic Acids, Amino Acids, and Sugar Alcohols in Potato Tubers Using a Nonaqueous Fractionation Method

Farre¹

2001

Plant Physiology

127

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The compartmentation of metabolism in heterotrophic plant tissues is poorly understood due to the lack of data on metabolite distributions and fluxes between subcellular organelles. The main reason for this is the lack of suitable experimental methods with which intracellular metabolism can be measured. Here, we describe a nonaqueous fractionation method that allows the subcellular distributions of metabolites in developing potato (Solanum tuberosum L. cv Desiree) tubers to be calculated. In addition, we have coupled this fractionation method to a recently described gas chromatography-mass spectrometry procedure that allows the measurement of a wide range of small metabolites. To calculate the subcellular metabolite concentrations, we have analyzed organelle volumes in growing potato tubers using electron microscopy. The relative volume distributions in tubers are very similar to the ones for source leaves. More than 60% of most sugars, sugar alcohols, organic acids, and amino acids were found in the vacuole, although the concentrations of these metabolites is often higher in the cytosol. Significant amounts of the substrates for starch biosynthesis, hexose phosphates, and ATP were found in the plastid. However, pyrophosphate was located almost exclusively in the cytosol. Calculation of the mass action ratios of sucrose synthase, UDP-glucose pyrophosphorylase, phosphoglucosisomerase, and phosphoglucomutase indicate that these enzymes are close to equilibrium in developing potato tubers. However, due to the low plastidic pyrophosphate concentration, the reaction catalyzed by ADP-glucose pyrophosphorylase was estimated to be far removed from equilibrium.Compartmentation is one of the distinguishing characteristics of plant metabolism (ap Rees, 1987). A true understanding of the nature and regulation of plant metabolic networks can only be achieved when the metabolic interactions between subcellular compartments have been charted and subjected to analysis through experimental procedures. Because of the profound difficulties associated with measuring enzymes, metabolites, and fluxes in specific subcellular compartments, our understanding of plant metabolism has lagged far behind that of animal and microbial systems.Although methods have been developed for the assay of subcellular metabolite levels in leaf tissue (Stitt et al., 1989), and the interactions between plastidial and cytosolic metabolism during photosynthesis have been partially characterized (Stitt, 1997), little is known about the metabolic networks in heterotrophic cells. There are two main reasons for this. First, there is a lack of suitable methods for organelle isolation, which is a particularly difficult problem in heterotrophic cells because these often contain large starch grains that cause extra damage to the organelles during fractionation. Second, although leaf metabolism is highly conserved between different species (Heineke et al., 1997), heterotrophic tissues usually form differentiated organs with specific functions and therefore studies ca...

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Section: Adenine and Uridine Nucleotides Show Different Partitioning supporting

confidence: 93%

Section: Hexose Phosphates and Glycolytic Intermediates Are Distributmentioning

confidence: 98%

Analysis of the Compartmentation of Glycolytic Intermediates, Nucleotides, Sugars, Organic Acids, Amino Acids, and Sugar Alcohols in Potato Tubers Using a Nonaqueous Fractionation Method

Farre¹

2001

Plant Physiology

127

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“…Futile cycles of Suc and starch turnover are also found in other growing storage organs (Hill and ap Rees, 1994;Geigenberger and Stitt, 2000;Geigenberger et al, 2004). They may allow sensitive regulation of flux by mediating an alternation between transient storage and remobilization depending on the momentary influx of photoassimilates (Geigenberger et al, 1994(Geigenberger et al, , 2004.…”

Section: Enzyme Activities In Developing Fruits Of S Lycopersicum Cumentioning

confidence: 99%

Enzyme Activity Profiles during Fruit Development in Tomato Cultivars andSolanum pennellii

Steinhauser

Koehl

et al. 2010

Plant Physiology

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Enzymes interact to generate metabolic networks. The activities of more than 22 enzymes from central metabolism were profiled during the development of fruit of the modern tomato cultivar Solanum lycopersicum 'M82' and its wild relative Solanum pennellii (LA0716). In S. pennellii, the mature fruit remains green and contains lower sugar and higher organic acid levels. These genotypes are the parents of a widely used near introgression line population. Enzymes were also profiled in a second cultivar, S. lycopersicum 'Moneymaker', for which data sets for the developmental changes of metabolites and transcripts are available. Whereas most enzyme activities declined during fruit development in the modern S. lycopersicum cultivars, they remained high or even increased in S. pennellii, especially enzymes required for organic acid synthesis. The enzyme profiles were sufficiently characteristic to allow stages of development and cultivars and the wild species to be distinguished by principal component analysis and clustering. Many enzymes showed coordinated changes during fruit development of a given genotype. Comparison of the correlation matrices revealed a large overlap between the two modern cultivars and considerable overlap with S. pennellii, indicating that despite the very different development responses, some basic modules are retained. Comparison of enzyme activity, metabolite profiles, and transcript profiles in S. lycopersicum 'Moneymaker' revealed remarkably little connectivity between the developmental changes of transcripts and enzymes and even less between enzymes and metabolites. We discuss the concept that the metabolite profile is an emergent property that is generated by complex network interactions.

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“…The recovery of small, representative amounts of each metabolite through the extraction, storage, and assay procedures has been documented previously (see Jelitto et al, 1992;Merlo et al, 1993;Geigenberger et al, 1994).…”

Section: Metabolite and Nucleotide Analysismentioning

confidence: 99%

The Sucrose Analog Palatinose Leads to a Stimulation of Sucrose Degradation and Starch Synthesis When Supplied to Discs of Growing Potato Tubers

2001

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In the present paper we investigated the effect of the sucrose (Suc) analog palatinose on potato (Solanum tuberosum) tuber metabolism. In freshly cut discs of growing potato tubers, addition of 5 mm palatinose altered the metabolism of exogenously supplied [U-14 C]Suc. There was slight inhibition of the rate of 14 C-Suc uptake, a 1.5-fold increase in the rate at which 14 C-Suc was subsequently metabolized, and a shift in the allocation of the metabolized label in favor of starch synthesis. The sum result of these changes was a 2-fold increase in the absolute rate of starch synthesis. The increased rate of starch synthesis was accompanied by a 3-fold increase in inorganic pyrophosphate, a 2-fold increase in UDP, decreased UTP/UDP, ATP/ADP, and ATP/AMP ratios, and decreased adenylate energy charge, whereas glycolytic and Krebs cycle intermediates were unchanged. In addition, feeding palatinose to potato discs also stimulated the metabolism of exogenous 14 C-glucose in favor of starch synthesis. In vitro studies revealed that palatinose is not metabolized by Suc synthases or invertases within potato tuber extracts. Enzyme kinetics revealed different effects of palatinose on Suc synthase and invertase activities, implicating palatinose as an allosteric effector leading to an inhibition of Suc synthase and (surprisingly) to an activation of invertase in vitro. However, measurement of tissue palatinose levels revealed that these were too low to have significant effects on Suc degrading activities in vivo. These results suggest that supplying palatinose to potato tubers represents a novel way to increase starch synthesis.

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When growing potato tubers are detached from their mother plant there is a rapid inhibition of starch synthesis, involving inhibition of ADP-glucose pyrophosphorylase

Cited by 68 publications

References 35 publications

Analysis of the Compartmentation of Glycolytic Intermediates, Nucleotides, Sugars, Organic Acids, Amino Acids, and Sugar Alcohols in Potato Tubers Using a Nonaqueous Fractionation Method

Analysis of the Compartmentation of Glycolytic Intermediates, Nucleotides, Sugars, Organic Acids, Amino Acids, and Sugar Alcohols in Potato Tubers Using a Nonaqueous Fractionation Method

Enzyme Activity Profiles during Fruit Development in Tomato Cultivars andSolanum pennellii

The Sucrose Analog Palatinose Leads to a Stimulation of Sucrose Degradation and Starch Synthesis When Supplied to Discs of Growing Potato Tubers

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