References of "Geigenberger, Peter"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailSucrose non-fermenting kinase 1 (SnRK1) coordinates metabolic and hormonal signals during pea cotyledon growth and differentiation.
Radchuk, Ruslana; Emery, R J Neil; Weier, Diana et al

in Plant Journal (The) (2010), 61(2), 324-38

Seed development passes through developmental phases such as cell division, differentiation and maturation: each have specific metabolic demands. The ubiquitous sucrose non-fermenting-like kinase (SnRK1 ... [more ▼]

Seed development passes through developmental phases such as cell division, differentiation and maturation: each have specific metabolic demands. The ubiquitous sucrose non-fermenting-like kinase (SnRK1) coordinates and adjusts physiological and metabolic demands with growth. In protoplast assays sucrose deprivation and hormone supplementation, such as with auxin and abscisic acid (ABA), stimulate SnRK1-promoter activity. This indicates regulation by nutrients: hormonal crosstalk under conditions of nutrient demand and cell proliferation. SnRK1-repressed pea (Pisum sativum) embryos show lower cytokinin levels and deregulation of cotyledonary establishment and growth, together with downregulated gene expression related to cell proliferation, meristem maintenance and differentiation, leaf formation, and polarity. This suggests that at early stages of seed development SnRK1 regulates coordinated cotyledon emergence and growth via cytokinin-mediated auxin transport and/or distribution. Decreased ABA levels and reduced gene expression, involved in ABA-mediated seed maturation and response to sugars, indicate that SnRK1 is required for ABA synthesis and/or signal transduction at an early stage. Metabolic profiling of SnRK1-repressed embryos revealed lower levels of most organic and amino acids. In contrast, levels of sugars and glycolytic intermediates were higher or unchanged, indicating decreased carbon partitioning into subsequent pathways such as the tricarbonic acid cycle and amino acid biosynthesis. It is hypothesized that SnRK1 mediates the responses to sugar signals required for early cotyledon establishment and patterning. As a result, later maturation and storage activity are strongly impaired. Changes observed in SnRK1-repressed pea seeds provide a framework for how SnRK1 communicates nutrient and hormonal signals from auxins, cytokinins and ABA to control metabolism and development. [less ▲]

Detailed reference viewed: 37 (9 ULg)
Full Text
See detailManipulating seed quality traits in pea (Pisum sativum L.) for improved feed and food
Vigeolas, Hélène ULg; Domoney, Claire; Charlton, A. et al

in Grain Legumes (2009), 52

Detailed reference viewed: 21 (4 ULg)
Full Text
Peer Reviewed
See detailCombined metabolomic and genetic approaches reveal a link between the polyamine pathway and albumin 2 in developing pea seeds.
Vigeolas, Hélène ULg; Chinoy, Catherine; Zuther, Ellen et al

in Plant Physiology (2008), 146(1), 74-82

Several legume seed proteins that are potentially allergenic, poorly digested by farm animals, and/or have undesirable functional properties, have been described. One of these is the albumin protein in ... [more ▼]

Several legume seed proteins that are potentially allergenic, poorly digested by farm animals, and/or have undesirable functional properties, have been described. One of these is the albumin protein in pea (Pisum sativum) called PA2. A naturally occurring mutant line that lacks PA2 has been exploited in studies to determine the biological function of this nonstorage protein in seed development. The mutant, which has a small seed, a tall plant phenotype, and lacks most of the PA2-encoding genes, has been crossed with a standard cultivar, 'Birte,' which contains PA2 to give rise to a recombinant inbred (RI) population. An F(3) line carrying the mutation and having a short plant phenotype has been used to generate backcross (BC) lines with 'Birte.' Despite having a lower albumin content, seeds from the mutant parent and RI lines lacking PA2 have an equivalent or higher seed nitrogen content. Metabolite profiling of seeds revealed major differences in amino acid composition and polyamine content in the two parent lines. This was investigated further in BC lines, where the effects of differences in seed size and plant height between the two parents were eliminated. Here, differences in polyamine synthesis were maintained as was a difference in total seed protein between the BC line lacking PA2 and 'Birte.' Analysis of enzyme activities in the pathways of polyamine synthesis revealed that the differences in spermidine content were attributable to changes in the overall activities of spermidine synthase and arginine decarboxylase. Although the genes encoding spermidine synthase and PA2 both localized to the pea linkage group I, the two loci were shown not to be closely linked and to have recombined in the BC lines. A distinct locus on linkage group III contains a gene that is related to PA2 but expressed predominantly in flowers. The results provide evidence for a role of PA2 in regulating polyamine metabolism, which has important functions in development, metabolism, and stress responses in plants. [less ▲]

Detailed reference viewed: 20 (4 ULg)
Full Text
See detailVERFAHREN ZUR VERÄNDERUNG DES ATP-ADP-VERHÄLTNISSES IN ZELLEN
Vigeolas, Hélène ULg; Zank, thorsten; Oswald, Oliver et al

Patent (2007)

(FR) L'invention concerne un procédé de modification du rapport ATP/ADP dans une cellule, un tissu, un organe, un micro-organisme ou une plante par modification de l'activité d'une protéine à hème dans la ... [more ▼]

(FR) L'invention concerne un procédé de modification du rapport ATP/ADP dans une cellule, un tissu, un organe, un micro-organisme ou une plante par modification de l'activité d'une protéine à hème dans la cellule. L'invention porte également sur l'application de ce procédé. [less ▲]

Detailed reference viewed: 47 (3 ULg)
Full Text
See detailVERFAHREN ZUR ERHÖHUNG DES GESAMTÖLGELHALTES IN ÖLPFLANZEN
Vigeolas, Hélène ULg; Zank, Thorsten; Oswald, Oliver et al

Patent (2007)

DE) Die Erfindung betrifft Verfahren zur Erhöhung des Gesamtölgehaltes und/oder des Gehalts an Glycerol-3-Phosphat in transgenen Ölpflanzen, die mindestens 20 Gew-% Ölsäure bezogen auf den ... [more ▼]

DE) Die Erfindung betrifft Verfahren zur Erhöhung des Gesamtölgehaltes und/oder des Gehalts an Glycerol-3-Phosphat in transgenen Ölpflanzen, die mindestens 20 Gew-% Ölsäure bezogen auf den Gesamtfettsäuregehalt enthalten, bevorzugt in pflanzlichen Samen, durch Expression von Glycerol-3-phosphatdehydrogenasen (G3PDH) aus Hefen, bevorzugt aus Saccharomyces cerevisiae. Vorteilhaft wird das im Verfahren gewonnene Öl und/oder die freien Fettsäure Polymeren, Nahrungsmitteln, Futtermitteln, Kosmetika, Pharmazeutika oder Produkten mit industriellen Anwendungen zugesetzt. [less ▲]

Detailed reference viewed: 18 (3 ULg)
Full Text
Peer Reviewed
See detailIncreasing seed oil content in oil-seed rape (Brassica napus L.) by over-expression of a yeast glycerol-3-phosphate dehydrogenase under the control of a seed-specific promoter.
Vigeolas, Hélène ULg; Waldeck, Peter; Zank, Thorsten et al

in Plant Biotechnology Journal (2007), 5(3), 431-41

Previous attempts to manipulate oil synthesis in plants have mainly concentrated on the genes involved in the biosynthesis and use of fatty acids, neglecting the possible role of glycerol-3-phosphate ... [more ▼]

Previous attempts to manipulate oil synthesis in plants have mainly concentrated on the genes involved in the biosynthesis and use of fatty acids, neglecting the possible role of glycerol-3-phosphate supply on the rate of triacylglycerol synthesis. In this study, a yeast gene coding for cytosolic glycerol-3-phosphate dehydrogenase (gpd1) was expressed in transgenic oil-seed rape under the control of the seed-specific napin promoter. It was found that a twofold increase in glycerol-3-phosphate dehydrogenase activity led to a three- to fourfold increase in the level of glycerol-3-phosphate in developing seeds, resulting in a 40% increase in the final lipid content of the seed, with the protein content remaining substantially unchanged. This was accompanied by a decrease in the glycolytic intermediate dihydroxyacetone phosphate, the direct precursor of glycerol-3-phosphate dehydrogenase. The levels of sucrose and various metabolites in the pathway from sucrose to fatty acids remained unaltered. The results show that glycerol-3-phosphate supply co-limits oil accumulation in developing seeds. This has important implications for strategies that aim to increase the overall level of oil in commercial oil-seed crops for use as a renewable alternative to petrol. [less ▲]

Detailed reference viewed: 50 (4 ULg)
Full Text
Peer Reviewed
See detailSymbiotic leghemoglobins are crucial for nitrogen fixation in legume root nodules but not for general plant growth and development.
Ott, Thomas; van Dongen, Joost T; Gunther, Catrin et al

in Current Biology (2005), 15(6), 531-5

Hemoglobins are ubiquitous in nature and among the best-characterized proteins. Genetics has revealed crucial roles for human hemoglobins, but similar data are lacking for plants. Plants contain symbiotic ... [more ▼]

Hemoglobins are ubiquitous in nature and among the best-characterized proteins. Genetics has revealed crucial roles for human hemoglobins, but similar data are lacking for plants. Plants contain symbiotic and nonsymbiotic hemoglobins; the former are thought to be important for symbiotic nitrogen fixation (SNF). In legumes, SNF occurs in specialized organs, called nodules, which contain millions of nitrogen-fixing rhizobia, called bacteroids. The induction of nodule-specific plant genes, including those encoding symbiotic leghemoglobins (Lb), accompanies nodule development. Leghemoglobins accumulate to millimolar concentrations in the cytoplasm of infected plant cells prior to nitrogen fixation and are thought to buffer free oxygen in the nanomolar range, avoiding inactivation of oxygen-labile nitrogenase while maintaining high oxygen flux for respiration. Although widely accepted, this hypothesis has never been tested in planta. Using RNAi, we abolished symbiotic leghemoglobin synthesis in nodules of the model legume Lotus japonicus. This caused an increase in nodule free oxygen, a decrease in the ATP/ADP ratio, loss of bacterial nitrogenase protein, and absence of SNF. However, LbRNAi plants grew normally when fertilized with mineral nitrogen. These data indicate roles for leghemoglobins in oxygen transport and buffering and prove for the first time that plant hemoglobins are crucial for symbiotic nitrogen fixation. [less ▲]

Detailed reference viewed: 20 (0 ULg)
Full Text
See detailVerfahren zur Veränderung des Gehalts von Speicherstoffen in Pflanzen
Vigeolas, Hélène ULg; Geigenberger, Peter; Langer, Anke et al

Patent (2004)

(FR) L'invention concerne un procédé de modification de la teneur en réserves de plantes, pour lequel on utilise des plantes modifiées exprimant de la leghémoglobine et/ou de l'hémoglobine. L'invention ... [more ▼]

(FR) L'invention concerne un procédé de modification de la teneur en réserves de plantes, pour lequel on utilise des plantes modifiées exprimant de la leghémoglobine et/ou de l'hémoglobine. L'invention concerne également les plantes correspondantes et leur utilisation. [less ▲]

Detailed reference viewed: 21 (3 ULg)
Full Text
Peer Reviewed
See detailPhloem import and storage metabolism are highly coordinated by the low oxygen concentrations within developing wheat seeds.
van Dongen, Joost T; Roeb, Gerhard W; Dautzenberg, Marco et al

in Plant Physiology (2004), 135(3), 1809-21

We studied the influence of the internal oxygen concentration in seeds of wheat (Triticum aestivum) on storage metabolism and its relation to phloem import of nutrients. Wheat seeds that were developing ... [more ▼]

We studied the influence of the internal oxygen concentration in seeds of wheat (Triticum aestivum) on storage metabolism and its relation to phloem import of nutrients. Wheat seeds that were developing at ambient oxygen (21%) were found to be hypoxic (2.1%). Altering the oxygen supply by decreasing or increasing the external oxygen concentration induced parallel changes in the internal oxygen tension. However, the decrease in internal concentration was proportionally less than the reduction in external oxygen. This indicates that decreasing the oxygen supply induces short-term adaptive responses to reduce oxygen consumption of the seeds. When external oxygen was decreased to 8%, internal oxygen decreased to approximately 0.5% leading to a decrease in energy production via respiration. Conversely, increasing the external oxygen concentration above ambient levels increased the oxygen content as well as the energy status of the seeds, indicating that under normal conditions the oxygen supply is strongly limiting for energy metabolism in developing wheat seeds. The intermediate metabolites of seed storage metabolism were not substantially affected when oxygen was either increased or decreased. However, at subambient external oxygen concentrations (8%) the metabolic flux of carbon into starch and protein, measured by injecting (14)C-Suc into the seeds, was reduced by 17% and 32%, respectively, whereas no significant effect was observed at superambient (40%) oxygen. The observed decrease in biosynthetic fluxes to storage compounds is suggested to be part of an adaptive response to reduce energy consumption preventing excessive oxygen consumption when oxygen supply is limited. Phloem transport toward ears exposed to low (8%) oxygen was significantly reduced within 1 h, whereas exposing ears to elevated oxygen (40%) had no significant effect. This contrasts with the situation where the distribution of assimilates has been modified by removing the lower source leaves from the plant, resulting in less assimilates transported to the ear in favor of transport to the lower parts of the plant. Under these conditions, with two strongly competing sinks, elevated oxygen (40%) did lead to a strong increase in phloem transport to the ear. The results show that sink metabolism is affected by the prevailing low oxygen concentrations in developing wheat seeds, determining the import rate of assimilates via the phloem. [less ▲]

Detailed reference viewed: 19 (0 ULg)
Full Text
Peer Reviewed
See detailEmbryo-specific reduction of ADP-Glc pyrophosphorylase leads to an inhibition of starch synthesis and a delay in oil accumulation in developing seeds of oilseed rape.
Vigeolas, Hélène ULg; Mohlmann, Torsten; Martini, Norbert et al

in Plant Physiology (2004), 136(1), 2676-86

In oil-storing Brassica napus (rape) seeds, starch deposition occurs only transiently in the early stages of development, and starch is absent from mature seeds. This work investigates the influence of a ... [more ▼]

In oil-storing Brassica napus (rape) seeds, starch deposition occurs only transiently in the early stages of development, and starch is absent from mature seeds. This work investigates the influence of a reduction of ADP-Glc pyrophosphorylase (AGPase) on storage metabolism in these seeds. To manipulate the activity of AGPase in a seed-specific manner, a cDNA encoding the small subunit of AGPase was expressed in the sense or antisense orientation under the control of an embryo-specific thioesterase promoter. Lines were selected showing an embryo-specific decrease in AGPase due to antisense and cosuppression at different stages of development. At early developmental stages (25 days after flowering), a 50% decrease in AGPase activity was accompanied by similar decreases in starch content and the rate of starch synthesis measured by injecting (14)C-Suc into seeds in planta. In parallel to inhibition of starch synthesis, the level of ADP-Glc decreased, whereas Glc 1-phosphate levels increased, providing biochemical evidence that inhibition of starch synthesis was due to repression of AGPase. At 25 days after flowering, repression of starch synthesis also led to a decrease in the rate of (14)C-Suc degradation and its further metabolism via other metabolic pathways. This was not accompanied by an increase in the levels of soluble sugars, indicating that Suc import was inhibited in parallel. Flux through glycolysis, the activities of hexokinase, and inorganic pyrophosphate-dependent phosphofructokinase, and the adenylate energy state (ATP to ADP ratio) of the transgenic seeds decreased, indicating inhibition of glycolysis and respiration compared to wild type. This was accompanied by a marked decrease in the rate of storage lipid (triacylglycerol) synthesis and in the fatty acid content of seeds. In mature seeds, glycolytic enzyme activities, metabolite levels, and ATP levels remained unchanged, and the fatty acid content was only marginally lower compared to wild type, indicating that the influence of AGPase on carbon metabolism and oil accumulation was largely compensated for in the later stages of seed development. Results indicate that AGPase exerts high control over starch synthesis at early stages of seed development where it is involved in establishing the sink activity of the embryo and the onset of oil accumulation. [less ▲]

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailIncreased levels of glycerol-3-phosphate lead to a stimulation of flux into triacylglycerol synthesis after supplying glycerol to developing seeds of Brassica napus L. in planta.
Vigeolas, Hélène ULg; Geigenberger, Peter

in Planta (2004), 219(5), 827-35

Glycerol-3-phosphate (glycerol-3P) is a primary substrate for triacylglycerol synthesis. In the present study, changes in the levels of glycerol-3P during rape (Brassica napus L.) seed development and the ... [more ▼]

Glycerol-3-phosphate (glycerol-3P) is a primary substrate for triacylglycerol synthesis. In the present study, changes in the levels of glycerol-3P during rape (Brassica napus L.) seed development and the influence of manipulating glycerol-3P levels on triacylglycerol synthesis were investigated. (i) Glycerol-3P levels were high in young seeds and decreased during seed development at 30 and 40 days after flowering (DAF), when lipid accumulation was maximal. (ii) To manipulate glycerol-3P levels in planta, various concentrations of glycerol were injected directly into 30-DAF seeds, which remained otherwise intact within their siliques and attached to the plant. Injection of 0-10 nmol glycerol led to a progressive increase in seed glycerol-3P levels within 28 h. (iii). Increased levels of glycerol-3P were accompanied by an increase in the flux of injected [14C]sucrose into total lipids and triacylglycerol, whereas fluxes to organic acids, amino acids, starch, protein and cell walls were not affected. (iv) When [14C]acetate was injected into seeds, label incorporation into total lipids and triacylglycerol increased progressively with increasing glycerol-3P levels. (v) There was a strong correlation between the level of glycerol-3P and the incorporation of injected [14C]acetate and [14C]sucrose into triacylglycerol. (v) The results provide evidence that the prevailing levels of glycerol-3P co-limit triacylglycerol synthesis in developing rape seeds. [less ▲]

Detailed reference viewed: 13 (0 ULg)
Full Text
See detailVERFAHREN ZUM ERHÖHEN DES ÖLGEHALTES IN PFLANZEN
Vigeolas, Hélène ULg; Renz, Andreas; Bauer, Jörg et al

Patent (2003)

The invention relates to methods for increasing the oil content in plants, preferably in the seeds of plants, by expression of glycerol-3-phosphatdehydrogenases (G3PDH) from yeast, preferably from ... [more ▼]

The invention relates to methods for increasing the oil content in plants, preferably in the seeds of plants, by expression of glycerol-3-phosphatdehydrogenases (G3PDH) from yeast, preferably from Saccharomyces cerevisiae. The invention also relates to expression constructs for the expression of G3PDH yeast in plants, preferably in the seeds of plants, transgenic plants expressing G3PDH, and to the use of said transgenic plants in the production of foodstuffs, feed, seeds, pharmaceuticals or fine chemicals, especially in the production of oils. [less ▲]

Detailed reference viewed: 19 (3 ULg)
Full Text
Peer Reviewed
See detailLipid storage metabolism is limited by the prevailing low oxygen concentrations within developing seeds of oilseed rape.
Vigeolas, Hélène ULg; van Dongen, Joost T; Waldeck, Peter et al

in Plant Physiology (2003), 133(4), 2048-60

The aim of this study was to investigate whether endogenous restrictions in oxygen supply are limiting for storage metabolism in developing oilseed rape (Brassica napus) seeds. Siliques were studied 30 d ... [more ▼]

The aim of this study was to investigate whether endogenous restrictions in oxygen supply are limiting for storage metabolism in developing oilseed rape (Brassica napus) seeds. Siliques were studied 30 d after flowering, when rapid lipid accumulation is occurring in the seeds. (a). By using microsensors, oxygen concentrations were measured within seeds and in the silique space between seeds. At ambient external oxygen (21% [v/v]) in the light, oxygen fell to 17% (v/v) between and 0.8% (v/v) within seeds. A step-wise reduction of the external oxygen concentration led within 2 h to a further decrease of internal oxygen concentrations, and a step-wise increase of the external oxygen concentration up to 60% (v/v) resulted in an increase in internal oxygen that rose to 30% (v/v) between and 8% (v/v) within seeds. (b). The increase in oxygen levels in the seeds was accompanied by a progressive increase in the levels of ATP, UTP, and the ATP to ADP and UTP to UDP ratios over the entire range from 0% to 60% (v/v) external oxygen. (c). To investigate metabolic fluxes in planta, 14C-sucrose was injected into seeds, which remained otherwise intact within their siliques. The increase in oxygen in the seeds was accompanied by a progressive increase in the rate of lipid (including triacylglycerol), protein and cell wall synthesis, and an increase in glycolytic flux over a range from sub- to superambient oxygen concentrations. In contrast to lipid synthesis, starch synthesis was not significantly increased at superambient oxygen levels. The levels of fermentation products such as lactate and glycerol-3P increased only at very low (0%-4% [v/v]) external oxygen concentrations. (d). When 14C-acetate or 14C-acetyl-coenzyme A (CoA) was injected into seeds, label incorporation into triacylglycerol progressively increased over the whole range of external oxygen concentrations from 0% to 60% (v/v). (e). Stimulation of lipid synthesis was accompanied by an increase in sugar levels and a decrease in the levels of hexose-phosphates and acetyl-CoA, indicating sucrose unloading and the use of acetyl-CoA as possible regulatory sites. (f). Increased lipid synthesis was also accompanied by an increase in the maximal activities of invertase and diacylglycerol acyltransferase. (g). The developmental shift from starch to lipid storage between 15 and 45 d after flowering was accompanied by an increase in the seed energy state. (h). The results show that at ambient oxygen levels, the oxygen supply is strongly limiting for energy metabolism and biosynthetic fluxes in growing rape seeds, affecting lipid synthesis more strongly than starch synthesis. The underlying mechanisms and implications for strategies to increase yield and storage product composition in oilseed crops are discussed. [less ▲]

Detailed reference viewed: 19 (0 ULg)
Full Text
Peer Reviewed
See detailSensitive and high throughput metabolite assays for inorganic pyrophosphate, ADPGlc, nucleotide phosphates, and glycolytic intermediates based on a novel enzymic cycling system.
Gibon, Yves; Vigeolas, Hélène ULg; Tiessen, Axel et al

in Plant Journal (The) (2002), 30(2), 221-35

Metabolite assays are required to characterise how metabolism changes between genotypes during development and in response to environmental perturbations. They provide a springboard to identify important ... [more ▼]

Metabolite assays are required to characterise how metabolism changes between genotypes during development and in response to environmental perturbations. They provide a springboard to identify important regulatory sites and investigate the underlying mechanisms. Due to their small size, Arabidopsis seeds pose a technical challenge for such measurements. A set of assays based on a novel enzymic cycling system between glycerol-3-phosphate dehydrogenase and glycerol-3-phosphate oxidase have been developed and optimised for use with growing Arabidopsis seeds. In combination with existing assays they provide a suite of high throughput, sensitive assays for the immediate precursors for starch (adenine diphosphate glucose) and lipid (acetyl coenzyme A, glycerol-3-phosphate) synthesis, as well as pyrophosphate, ATP, ADP and most of the glycolytic intermediates. A method is also presented to rapidly quench intact siliques, lyophilise them and then manually separate seeds for metabolite analysis. These techniques are used to investigate changes in overall seed metabolite levels during development and maturation, and in response to a stepwise decrease of the external oxygen concentration. [less ▲]

Detailed reference viewed: 12 (0 ULg)