ORCID Profile
0000-0001-7351-1803
Current Organisation
Institut National de la Recherche Agronomique
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Publisher: Springer Science and Business Media LLC
Date: 09-1995
DOI: 10.1007/BF00202657
Publisher: Portland Press Ltd.
Date: 06-1994
DOI: 10.1042/BJ3000557
Abstract: Young pea leaves contain two structurally different forms of acetyl-CoA carboxylase (EC 6.4.1.2 ACCase). A minor form, which accounted for about 20% of the total ACCase activity in the whole leaf, was detected in the epidermal tissue. This enzyme was soluble and was purified to homogeneity from young pea leaf extracts. It consisted of a dimer of two identical biotinyl subunits of molecular mass 220 kDa. In this respect, this multifunctional enzyme was comparable with that described in other plants and in other eukaryotes. A predominant form was present in both the epidermal and mesophyll tissues. In mesophyll protoplasts, ACCase was detected exclusively in the soluble phase of chloroplasts. This enzyme was partially purified from pea chloroplasts and consisted of a freely dissociating complex, the activity of which may be restored by combination of its separated constituents. The partially purified enzyme was composed of several subunits of molecular masses ranging from 32 to 79 kDa, for a native molecular mass & 600 kDa. One of these subunits, of molecular mass 38 kDa, was biotinylated. This complex subunit structure was comparable with that of microorganisms and was referred to as a ‘prokaryotic’ form of ACCase. Biochemical parameters were determined for both ACCase forms. Finally, both pea leaf ACCases exhibited different sensitivities towards the grass ACCase herbicide, diclofop. This compound had no effect on the ‘prokaryotic’ form of ACCase, while the ‘eukaryotic’ form was strongly inhibited.
Publisher: Frontiers Media SA
Date: 14-02-2018
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.JPLPH.2007.10.016
Abstract: Here we examined the effects of root hypoxia (1-2% oxygen) on the physiology of the plant and on the biochemical composition of fruits in tomato (Solanum lycopersicum cv. Micro-Tom) plants submitted to gradual root hypoxia at first flower anthesis. Root hypoxia enhanced nitrate absorption with a concomitant release of nitrite and ammonium into the medium, a reduction of leaf photosynthetic activity and chlorophyll content, and an acceleration of fruit maturation, but did not affect final fruit size. Quantitative metabolic profiling of mature pericarp extracts by (1)H NMR showed that levels of major metabolites including sugars, organic acids and amino acids were not modified. However, ammonium concentration increased dramatically in fruit flesh, and ascorbate and lycopene concentrations decreased. Our data indicate that the unfavorable effects of root hypoxia on fruit quality cannot be explained by two of the well-known effects of root hypoxia on the plant, namely a decrease in photosynthesis or an excess in ethylene production, but may instead result from disturbances in the supply of either growth regulators or ammonium, by the roots.
Publisher: Oxford University Press (OUP)
Date: 23-09-2005
Abstract: The cell expansion phase contributes in determining the major characteristics of a fleshy fruit and represents two-thirds of the total fruit development in tomato (Solanum lycopersicum). So far, it has received very little attention. To evaluate the interest of a genomic scale approach, we performed an initial sequencing of approximately 1,200 cell expansion stage-related sequence tags from tomato fruit at 8, 12, and 15 d post anthesis. Interestingly, up to approximately 35% of the expressed sequence tags showed no homology with available tomato expressed sequence tags and up to approximately 21% with any known gene. Microarrays spotted with expansion phase-related cDNAs and other fruit cDNAs involved in various developmental processes were used (1) to profile gene expression in developing fruit and other plant organs and (2) to compare two growing fruit tissues engaged mostly in cell ision (exocarp) or in cell expansion (locular tissue surrounding the seeds). Reverse transcription-polymerase chain reaction analysis was further used to confirm microarray results and to specify expression profiles of selected genes (24) in various tissues from expanding fruit. The wide range of genes expressed in the exocarp is consistent with a protective function and with a high metabolic activity of this tissue. In addition, our data show that the expansion of locular cells is concomitant with the expression of genes controlling water flow, organic acid synthesis, sugar storage, and photosynthesis and suggest that hormones (auxin and gibberellin) regulate this process. The data presented provide a basis for tissue-specific analyses of gene function in growing tomato fruit.
Publisher: Elsevier BV
Date: 08-2022
DOI: 10.1016/J.PLAPHY.2022.05.025
Abstract: Mitochondria are the major organelles of energy production however, active mitochondria can decline their energetic role and show a dysfunctional status. Mitochondrial dysfunction was induced by high non-physiological level of L-galactone-1,4-lactone (L-GalL), the precursor of ascorbate (AsA), in plant mitochondria. The dysfunction induced by L-GalL was associated with the fault in the mitochondrial electron partition and reactive oxygen species (ROS) over-production. Using mitochondria from RNAi-plant lines harbouring silenced L-galactone-1,4-lactone dehydrogenase (L-GalLDH) activity, it was demonstrated that such dysfunction is dependent on this enzyme activity. The capacity of alternative respiration was strongly decreased by L-GalL, probably mediated by redox-inactivation of the alternative oxidase (AOX) enzyme. Although, alternative respiration was shown to be the key factor that helps support AsA synthesis in dysfunctional mitochondria. Experiments with respiratory inhibitors showed that ROS formation and mitochondrial dysfunction were more associated with the decline in the activities of COX (cytochrome oxidase) and particularly AOX than with the lower activities of respiratory complexes I and III. The application of high L-GalL concentrations induced proteomic changes that indicated alterations in proteins related to oxidative stress and energetic status. However, supra-optimal L-GalL concentration was not deleterious for plants. Instead, the L-GalLDH activity could be positive. Indeed, it was found that wild type plants performed better growth than L-GalLDH-RNAi plants in response to high non-physiological L-GalL concentrations.
Publisher: Japanese Society for Horticultural Science
Date: 2018
Publisher: Wiley
Date: 10-1993
DOI: 10.1111/J.1432-1033.1993.TB18267.X
Abstract: Biotin biosynthesis was investigated in lavender cell cultures (Lavandula vera L.). Two different biological assays and two different HPLC procedures were used to identify all the intermediates involved in biotin biosynthesis. The pathway for biotin biosynthesis could be analyzed starting with [3H]pimelic acid as precursor, leading to labelled biotin and even to labelled biotinylated enzymes. Intermediates known from the bacterial pathway (7-oxo-8-amino-pelargonic acid, 7,8-diamino-pelargonic acid, dethiobiotin) were present in detectable amounts. Pimelic acid activation to pimeloyl-CoA could be observed. In contrast to bacterial cells, an unknown stable labelled intermediate, named compound A, accumulated. This compound coeluted with an authentic s le of 9-mercaptodethiobiotin from HPLC with an anion-exchange column and was as effective as biotin in supporting the growth of the strain bioB105 of Escherichia coli. When 3H-labelled compound A was added to the growth medium of the lavender cells it was incorporated in an acidomycin-sensitive manner into biotin. [3H]Dethiobiotin was incorporated into both compound A and biotin. These results strongly suggest that, in higher plant cells, the reaction catalysed by biotin synthase may proceed in two distinct steps involving mercaptodethiobiotin (9-mercaptodethiobiotin?) as an intermediate.
Publisher: Oxford University Press (OUP)
Date: 04-2003
DOI: 10.1093/JXB/ERG113
Abstract: Two-month-old tomato plants were submitted to day/night cycles and to prolonged darkness in order to investigate the physiological and biochemical response to sugar starvation in sink organs. Roots appeared particularly sensitive to the cessation of photosynthesis, as revealed by the reduction of the growth rate and the decline of the carbohydrate and protein content. Therefore, excised tomato roots were used as a model to deepen the characterization of sugar starvation symptoms. In excised roots, the endogenous sugars were rapidly exhausted and significant degradation of protein was observed. Glutamine and asparagine accounted for most of the nitrogen released by protein breakdown. Respiration declined and proliferation- and growth-associated genes were repressed soon after the beginning of the sugar depletion. Among the genes studied, only the gene encoding asparagine synthetase was strongly induced. All the starvation symptoms were reversible when the roots were resupplied with sugar. When the culture conditions deteriorated, the metabolic and molecular changes led to the triggering of apoptosis of the root cells.
Publisher: Springer Science and Business Media LLC
Date: 03-2002
DOI: 10.1007/S00425-001-0687-Z
Abstract: Malic and citric acids accumulate in cherry tomato (Lycopersicon esculentum Mill.) fruit during the period of rapid growth, from the end of cell ision to the onset of ripening. The involvement of phospho enolpyruvate carboxylase (PEPCase, EC 4.1.1.31) in organic acid accumulation and tomato fruit development was investigated. Two PEPCases, named LYCes Ppc1 and LYCes Ppc2 and mapped to chromosomes 12 and 7, respectively, were shown to be differentially expressed during tomato fruit development. LYCes Ppc1 mRNA was present in all fruit tissues and in all other plant organs examined. In contrast, LYCes Ppc2 was strongly and specifically expressed in fruit from the end of cell ision to ripening. No LYCes Ppc2 expression was detected by northern blot in other plant tissues. In fruit, the increase in LYCes Ppc2 mRNA was closely followed by an increase in fruit PEPCase protein and activity, and was coincident with the increased accumulation of malate and citrate during the initial period of rapid growth rate, from 8 to 20 days post anthesis. Localization of LYCes Ppc2 mRNA in young tomato fruit by in situ hybridization revealed that LYCes Ppc2 is preferentially expressed in large cells of the pericarp and in enlarging cells of the gel surrounding the seeds. Examination of the kinetic and regulatory properties of the PEPCases of growing and ripening fruit further showed that PEPCase in growing fruit is less sensitive to low pH and malate inhibition, indicating a high phosphorylation state and/or the presence of a PEPCase isoform with these characteristics. Taken together, these results indicate that in developing tomato fruit PEPCase is probably important in permitting the synthesis of organic acids to provide the turgor pressure necessary for cell expansion.
Publisher: Wiley
Date: 18-07-2012
DOI: 10.1111/J.1365-3040.2012.02564.X
Abstract: The regulation of carbon allocation between photosynthetic source leaves and sink tissues in response to stress is an important factor controlling plant yield. Ascorbate oxidase is an apoplastic enzyme, which controls the redox state of the apoplastic ascorbate pool. RNA interference was used to decrease ascorbate oxidase activity in tomato (Solanum lycopersicum L.). Fruit yield was increased in these lines under three conditions where assimilate became limiting for wild-type plants: when fruit trusses were left unpruned, when leaves were removed or when water supply was limited. Several alterations in the transgenic lines could contribute to the improved yield and favour transport of assimilate from leaves to fruits in the ascorbate oxidase lines. Ascorbate oxidase plants showed increases in stomatal conductance and leaf and fruit sugar content, as well as an altered apoplastic hexose:sucrose ratio. Modifications in gene expression, enzyme activity and the fruit metabolome were coherent with the notion of the ascorbate oxidase RNAi lines showing altered sink strength. Ascorbate oxidase may therefore be a target for strategies aimed at improving water productivity in crop species.
Publisher: Wiley
Date: 22-12-2020
DOI: 10.1111/TPJ.15077
Publisher: Wiley
Date: 12-2002
Publisher: Oxford University Press (OUP)
Date: 02-02-2007
Publisher: Oxford University Press (OUP)
Date: 26-09-2019
DOI: 10.1093/JXB/ERZ421
Abstract: Chilling tolerance in maize is associated with efficient modulation of sucrose/starch metabolism which might be linked to a strong alteration in biosynthesis of nucleotide sugars.
Publisher: Elsevier BV
Date: 09-2022
DOI: 10.1016/J.PLANTSCI.2022.111348
Abstract: Increased synthesis of H
Publisher: Oxford University Press (OUP)
Date: 13-04-2023
Abstract: Ascorbate (vitamin C) is an essential antioxidant in fresh fruits and vegetables. To gain insight into the regulation of ascorbate metabolism in plants, we studied mutant tomato plants (Solanum lycopersicum) that produce ascorbate-enriched fruits. The causal mutation, identified by a mapping-by-sequencing strategy, corresponded to a knock-out recessive mutation in a class of photoreceptor named PAS/LOV protein (PLP), which acts as a negative regulator of ascorbate biosynthesis. This trait was confirmed by CRISPR/Cas9 gene editing and further found in all plant organs, including fruit that accumulated 2 to 3 times more ascorbate than in the WT. The functional characterization revealed that PLP interacted with the 2 isoforms of GDP-L-galactose phosphorylase (GGP), known as the controlling step of the L-galactose pathway of ascorbate synthesis. The interaction with GGP occurred in the cytoplasm and the nucleus, but was abolished when PLP was truncated. These results were confirmed by a synthetic approach using an animal cell system, which additionally demonstrated that blue light modulated the PLP-GGP interaction. Assays performed in vitro with heterologously expressed GGP and PLP showed that PLP is a noncompetitive inhibitor of GGP that is inactivated after blue light exposure. This discovery provides a greater understanding of the light-dependent regulation of ascorbate metabolism in plants.
Publisher: Oxford University Press (OUP)
Date: 07-1993
DOI: 10.1104/PP.102.3.957
Abstract: 3-Methylcrotonyl-coenzyme A (CoA) carboxylase was purified to homogeneity from pea (Pisum sativum L.) leaf and potato (Solanum tuberosum L.) tuber mitochondria. The native enzyme has an apparent molecular weight of 530,000 in pea leaf and 500,000 in potato tuber as measured by gel filtration. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate disclosed two nonidentical subunits. The larger subunit (B subunit) is biotinylated and has an apparent molecular weight of 76,000 in pea leaf and 74,000 in potato tuber. The smaller subunit (A subunit) is biotin free and has an apparent molecular weight of 54,000 in pea leaf and 53,000 in potato tuber. The biotin content of the enzyme is 1 mol/133,000 g of protein and 1 mol/128,000 g of protein in pea leaf and potato tuber, respectively. These values are consistent with an A4B4 tetrameric structure for the native enzyme. Maximal 3-methylcrotonyl-CoA carboxylase activity was found at pH 8 to 8.3 and at 35 to 38[deg]C in the presence of Mg2+. Kinetic constants (apparent Km values) for the enzyme substrates 3-methylcrotonyl-CoA, ATP, and HCO3- were: 0.1 mM, 0.1 mM, and 0.9 mM, respectively, for pea leaf 3-methylcrotonyl-CoA carboxylase and 0.1 mM, 0.07 mM, and 0.34 mM, respectively, for potato tuber 3-methylcrotonyl-CoA carboxylase. A steady-state kinetic analysis of the carboxylase-catalyzed carboxylation of 3-methylcrotonyl-CoA gave rise to parallel line patterns in double reciprocal plots of initial velocity with the substrate pairs 3-methylcrotonyl-CoA plus ATP and 3-methylcrotonyl-CoA plus HCO3- and an intersecting line pattern with the substrate pair HCO3- plus ATP. It was concluded that the kinetic mechanism involves a double displacement. Purified 3-methylcrotonyl-CoA carboxylase was inhibited by end products of the reaction catalyzed, namely ADP and orthophosphate, and by 3-hydroxy-3-methylglutaryl-CoA. Finally, as for the 3-methylcrotonyl-CoA carboxylases from mammalian and bacterial sources, plant 3-methylcrotonyl-CoA carboxylase was sensitive to sulfhydryl and arginyl reagents.
Publisher: Springer Science and Business Media LLC
Date: 22-01-2020
DOI: 10.1007/S00425-020-03345-X
Abstract: Reduced GDP-L-galactose phosphorylase expression and deficiency of ascorbic acid content lead to decreased fruit set and yield in tomato plants. Reduced GDP-L-galactose phosphorylase expression and deficiency of ascorbic acid content lead to decreased fruit set and yield in tomato plants. GDP-L-galactose phosphorylase (GGP) catalyzes the first step committed to ascorbic acid synthesis. The participation of GDP-L-galactose phosphorylase and ascorbate in tomato fruit production and quality was studied in this work using two SlGGP1 deficient EMS Micro-Tom mutants. The SlGGP1 mutants display decreased concentrations of ascorbate in roots, leaves, flowers, and fruit. The initiation of anthesis is delayed in ggp1 plants but the number of flowers is similar to wild type. The number of fruits is reduced in ggp1 mutants with an increased in idual weight. However, the whole fruit biomass accumulation is reduced in both mutant lines. Fruits of the ggp1 plants produce more ethylene and show higher firmness and soluble solids content than the wild type after the breaker stage. Leaf CO
Publisher: Oxford University Press (OUP)
Date: 17-02-2006
DOI: 10.1093/JXB/ERJ082
Abstract: Changes in photoassimilate partitioning between source and sink organs significantly affect fruit development and size. In this study, a comparison was made of tomato plants (Solanum lycopersicum L.) grown under a low fruit load (one fruit per truss, L1 plants) and under a standard fruit load (five fruits per truss, L5 plants), at morphological, biochemical, and molecular levels. Fruit load reduction resulted in increased photoassimilate availability in the plant and in increased growth rates in all plant organs analysed (root, stem, leaf, flower, and fruit). Larger flower and fruit size in L1 plants were correlated with higher cell number in the pre-anthesis ovary. This was probably due to the acceleration of the flower growth rate since other flower developmental parameters (schedule and time-course) remained otherwise unaffected. Using RT-PCR, it was shown that the transcript levels of CYCB2 (cyclin) and CDKB2 (cyclin-dependent kinase), two mitosis-specific genes, strongly increased early in developing flower buds. Remarkably, the transcript abundance of CYCD3 , a D-type cyclin potentially involved in cell cycle regulation in response to mitogenic signals, also increased by more than 5-fold at very early stages of L1 flower development. By contrast, transcripts from fw2.2, a putative negative regulator of cell ision in tomato fruit, strongly decreased in developing flower bud, as confirmed by in situ hybridization studies. Taken together, these results suggest that changes in carbohydrate partitioning could control fruit size through the regulation of cell proliferation-related genes at very early stages of flower development.
Publisher: Wiley
Date: 11-2009
Publisher: Oxford University Press (OUP)
Date: 05-10-2007
Abstract: l-Galactono-1,4-lactone dehydrogenase (EC 1.3.2.3) catalyzes the last step in the main pathway of vitamin C (l-ascorbic acid) biosynthesis in higher plants. In this study, we first characterized the spatial and temporal expression of SlGalLDH in several organs of tomato (Solanum lycopersicum) plants in parallel with the ascorbate content. P35S:SlgalldhRNAi silenced transgenic tomato lines were then generated using an RNAi strategy to evaluate the effect of any resulting modification of the ascorbate pool on plant and fruit development. In all P35S:SlgalldhRNAi plants with reduced SlGalLDH transcript and activity, plant growth rate was decreased. Plants displaying the most severe effects (dwarf plants with no fruit) were excluded from further analysis. The most affected lines studied exhibited up to an 80% reduction in SlGalLDH activity and showed a strong reduction in leaf and fruit size, mainly as a consequence of reduced cell expansion. This was accompanied by significant changes in mitochondrial function and altered ascorbate redox state despite the fact that the total ascorbate content remained unchanged. By using a combination of transcriptomic and metabolomic approaches, we further demonstrated that several primary, like the tricarboxylic acid cycle, as well as secondary metabolic pathways related to stress response were modified in leaves and fruit of P35S:SlgalldhRNAi plants. When taken together, this work confirms the complexity of ascorbate regulation and its link with plant metabolism. Moreover, it strongly suggests that, in addition to ascorbate synthesis, GalLDH could play an important role in the regulation of cell growth-related processes in plants.
Publisher: Oxford University Press (OUP)
Date: 06-1992
DOI: 10.1104/PP.99.2.450
Publisher: Cold Spring Harbor Laboratory
Date: 31-10-2019
DOI: 10.1101/825208
Abstract: Attempts to improve the ascorbate (AsA) content of plants are still dealing with the limited understanding of why exists a wide variability of this powerful anti-oxidant molecule in different plant sources, species and environmental situations. In plant mitochondria, the last step of AsA synthesis is catalyzed by the enzyme L-galactone-1,4-lactone dehydrogenase (L-GalLDH). By using GalLDH-RNAi silencing plant lines, biochemical and proteomic approaches, we here discovered that, in addition to accumulate this antioxidant, mitochondria synthesize AsA to down-regulate the respiratory activity and the cellular energy provision. The work reveals that the AsA synthesis pathway within mitochondria is a branched electron transfer process that channels electrons towards the alternative oxidase, interfering with conventional electron transport. It was unexpectedly found that significant hydrogen peroxide is generated during AsA synthesis, which affects the AsA level. The induced AsA synthesis shows proteomic alterations of mitochondrial and extra-mitochondrial proteins related to oxidative and energetic metabolism. The most identified proteins were known components of plant responses to high light acclimation, programmed cell death, oxidative stress, senescence, cell expansion, iron and phosphorus starvation, different abiotic stress athogen attack responses and others. We propose that changing the electron flux associated with AsA synthesis might be part of a new mechanism by which the L-GalLDH enzyme would adapt plant mitochondria to fluctuating energy demands and redox status occurring under different physiological contexts.
Publisher: Frontiers Media SA
Date: 11-10-2019
Publisher: Wiley
Date: 07-08-2023
DOI: 10.1111/NPH.19160
Abstract: The ascorbate–glutathione (ASC–GSH) cycle is at the heart of redox metabolism, linking the major redox buffers with central metabolism through the processing of reactive oxygen species (ROS) and pyridine nucleotide metabolism. Tomato fruit development is underpinned by changes in redox buffer contents and their associated enzyme capacities, but interactions between them remain unclear. Based on quantitative data obtained for the core redox metabolism, we built an enzyme‐based kinetic model to calculate redox metabolite concentrations with their corresponding fluxes and control coefficients. Dynamic and associated regulations of the ASC–GSH cycle throughout the whole fruit development were analysed and pointed to a sequential metabolic control of redox fluxes by ASC synthesis, NAD(P)H and ROS availability depending on the developmental phase. Furthermore, we highlighted that monodehydroascorbate reductase and the availability of reducing power were found to be the main regulators of the redox state of ASC and GSH during fruit growth under optimal conditions. Our kinetic modelling approach indicated that tomato fruit development displayed growth phase‐dependent redox metabolism linked with central metabolism via pyridine nucleotides and H 2 O 2 availability, while providing a new tool to the scientific community to investigate redox metabolism in fruits.
Publisher: Elsevier BV
Date: 03-2011
Publisher: Elsevier BV
Date: 11-2009
Publisher: Japanese Society for Plant Cell and Molecular Biology
Date: 2013
Publisher: Elsevier BV
Date: 09-2010
Publisher: Japanese Society for Plant Cell and Molecular Biology
Date: 2013
Publisher: Wiley
Date: 06-02-2014
DOI: 10.1111/TPJ.12418
Abstract: Limitations in our understanding about the mechanisms that underlie source-sink assimilate partitioning are increasingly becoming a major hurdle for crop yield enhancement via metabolic engineering. By means of a comprehensive approach, this work reports the functional characterization of a DnaJ chaperone related-protein (named as SPA sugar partition-affecting) that is involved in assimilate partitioning in tomato plants. SPA protein was found to be targeted to the chloroplast thylakoid membranes. SPA-RNAi tomato plants produced more and heavier fruits compared with controls, thus resulting in a considerable increment in harvest index. The transgenic plants also displayed increased pigment levels and reduced sucrose, glucose and fructose contents in leaves. Detailed metabolic and enzymatic activities analyses showed that sugar phosphate intermediates were increased while the activity of phosphoglucomutase, sugar kinases and invertases was reduced in the photosynthetic organs of the silenced plants. These changes would be anticipated to promote carbon export from foliar tissues. The combined results suggested that the tomato SPA protein plays an important role in plastid metabolism and mediates the source-sink relationships by affecting the rate of carbon translocation to fruits.
Publisher: Wiley
Date: 02-1991
DOI: 10.1111/J.1432-1033.1991.TB15752.X
Abstract: The activation of oxidized chloroplast fructose-1,6-bisphosphatase by fructose 2,6-bisphosphate and magnesium previously described at pH 7.5 [Soulié et al. (1988) Eur. J. Biochem. 176, 111-117] has now been studied at pH 8, the pH which prevails under light conditions in the chloroplast stroma. The process obeys a hysteretic mechanism but the rate of activation is considerably increased with half-times down to 50 s and the apparent dissociation constant of fructose 2,6-bisphosphate from the enzyme is lowered from 1 mM at pH 7.5 to 3.3 microM at pH 8. The process is strictly metal-dependent with a half-saturation concentration of 2.54 mM for magnesium. The conformational transition postulated in our hysteretic model has been investigated through both the spectrophometric and chemical modification approaches. The activation of the enzyme by fructose 2,6-bisphosphate in the presence of magnesium results in a slow modification of the ultraviolet absorption spectrum of the enzyme with an overall increase of 3% at 290 nm. The same treatment leads to the protection of two free sulfhydryls and an increased reactivity of one sulfhydryl group/enzyme monomer to modification by 5,5'-dithiobis(2-nitrobenzoic acid). The titration of the exposed cysteinyl residue prevents the relaxation of enzyme species induced by fructose 2,6-bisphosphate to the native form. The activation of chloroplast fructose-1,6-bisphosphatase by fructose 2,6-bisphosphate is discussed both with respect to the understanding of the overall regulation properties of the enzyme and to a possible physiological significance of this process.
Publisher: Springer Science and Business Media LLC
Date: 10-02-2009
Publisher: International Society for Horticultural Science (ISHS)
Date: 08-2014
Publisher: Elsevier BV
Date: 05-1993
Abstract: Cytosol and vacuoles from protoplasts, chloroplasts, and mitochondria from green pea (Pisum sativum) leaves were purified and examined for their biotin content. The bulk of free biotin was shown to be exclusively associated with the cytosolic fraction at a concentration of about 4 pmol/mg protein and no bound biotin was detected. The bulk of bound biotin (biotin-containing carboxylases) was associated with the soluble fraction of chloroplasts and mitochondria at a concentration of about 1.2 and 13 microM, respectively. No free biotin was detected in these organelles. Western blot analysis of total, chloroplastic, and mitochondrial polypeptides, using horseradish peroxidase-labeled streptavidin, revealed three biotin-containing polypeptides with molecular mass of 220,000, 76,000 and 34,000. All were detected in the total pea leaf extract, but the M(r) 76,000 and the M(r) 34,000 biotinylated polypeptides were only detected in mitochondria and chloroplasts, respectively. 3-Methylcrotonyl-coenzyme A carboxylase and acetyl-coenzyme A carboxylase activities were measured in these two compartments, respectively. Previously, it has been shown that the M(r) 76,000 polypeptide was the biotinylated subunit of the mitochondrial 3-methylcrotonyl-coenzyme A carboxylase. In this paper, the origin and putative function of free biotin located in cytosol are discussed.
Publisher: Springer Science and Business Media LLC
Date: 07-08-2020
DOI: 10.1007/S00425-020-03440-Z
Abstract: The oxidant/antioxidant balance affects the ripening time of tomato fruit. Ripening of tomato fruit is associated with several modifications such as loss of cell wall firmness and transformation of chloroplasts to chromoplasts. Besides a peak in H
Publisher: Public Library of Science (PLoS)
Date: 17-05-2012
Publisher: Elsevier BV
Date: 11-2010
Publisher: Frontiers Media SA
Date: 18-09-2019
Publisher: Oxford University Press (OUP)
Date: 02-02-2021
DOI: 10.1093/JXB/ERAB040
Abstract: Ascorbate is a major antioxidant buffer in plants. Several approaches have been used to increase the ascorbate content of fruits and vegetables. Here, we combined forward genetics with mapping-by-sequencing approaches using an ethyl methanesulfonate (EMS)-mutagenized Micro-Tom population to identify putative regulators underlying a high-ascorbate phenotype in tomato fruits. Among the ascorbate-enriched mutants, the family with the highest fruit ascorbate level (P17C5, up to 5-fold wild-type level) had strongly impaired flower development and produced seedless fruit. Genetic characterization was performed by outcrossing P17C5 with cv. M82. We identified the mutation responsible for the ascorbate-enriched trait in a cis-acting upstream open reading frame (uORF) involved in the downstream regulation of GDP-l-galactose phosphorylase (GGP). Using a specific CRISPR strategy, we generated uORF-GGP1 mutants and confirmed the ascorbate-enriched phenotype. We further investigated the impact of the ascorbate-enriched trait in tomato plants by phenotyping the original P17C5 EMS mutant, the population of outcrossed P17C5 × M82 plants, and the CRISPR-mutated line. These studies revealed that high ascorbate content is linked to impaired floral organ architecture, particularly anther and pollen development, leading to male sterility. RNA-seq analysis suggested that uORF-GGP1 acts as a regulator of ascorbate synthesis that maintains redox homeostasis to allow appropriate plant development.
Publisher: Japanese Society for Plant Cell and Molecular Biology
Date: 2011
Publisher: Wiley
Date: 02-2010
DOI: 10.1111/J.1365-3040.2010.02139.X
Abstract: Tomato fruit growth and composition depend on both genotype and environment. This paper aims at studying how fruit phenotypic responses to changes in carbon availability can be influenced by genotype, and at identifying genotype-dependent and -independent changes in gene expression underlying variations in fruit growth and composition. We grew a parental line (Solanum lycopersicum) and an introgression line from Solanum chmielewskii harbouring quantitative trait loci for fresh weight and sugar content under two fruit loads (FL). Lowering FL increased fruit cell number and reduced fruit developmental period in both genotypes. In contrast, fruit cell size was increased only in the parental line. Modifications in gene expression were monitored using microarrays and RT-qPCR for a subset of genes. FL changes induced more deployments of regulation systems (transcriptional and post-transcriptional) than massive adjustments of whole primary metabolism. Interactions between genotype and FL occurred on 99 genes mainly linked to hormonal and stress responses, and on gene expression kinetics. Links between gene expression and fruit phenotype were found for aquaporin expression levels and fruit water content, and invertase expression levels and sugar content. In summary, the present data emphasized age- and genotype-dependent responses of tomato fruit to carbon availability, at phenotypic as well as gene expression level.
Publisher: Public Library of Science (PLoS)
Date: 19-12-2013
Publisher: Oxford University Press (OUP)
Date: 05-07-2016
DOI: 10.1093/JXB/ERW260
Location: No location found
No related grants have been discovered for Pierre Baldet.