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The bZIP transcription factor (TF) SlTGA2.2 was previously highlighted as a possible hub in a network regulating fruit growth and transition to ripening (maturation phase). It belongs to a clade of TFs well known for their involvement in the regulation of the salicylic acid–dependent systemic acquired resistance. To investigate if this TGA TF plays a role in tomato fruit growth and maturation, we took advantage of the fruit-specific SlPPC2 promoter (PPC2pro) to target the expression of a SlTGA2.2-SRDX chimeric repressor in a developmental window restricted to early fruit growth and maturation. Here, we show that this SlTGA2.2-SRDX repressor alters early fruit development and metabolism, including chloroplast number and structure, considerably extends the time necessary to reach the mature green stage and slows down fruit ripening. RNA sequencing and plant hormone analyses reveal that PPC2pro:SlTGA2.2-SRDX fruits are maintained in an immature stage as long as PPC2pro is active, through early modifications of plant hormonal signaling and down-regulation of MADS-RIN and NAC-NOR ripening regulators. Once PPC2pro becomes inactive and therefore SlTGA2.2-SRDX expression is reduced, ripening can proceed, albeit at a slower pace than normal. Altogether, this work emphasizes the developmental continuum between fruit growth, maturation and ripening and provides a useful tool to alter and study the molecular bases of tomato fruit transition to ripening.

International audience; Ascorbate is a major antioxidant buffer in plants, so several approaches have been developed to increase the ascorbate contents of fruits and vegetables. In this study, we combined forward genetics with mapping-by-sequencing approaches using an EMSMicro-Tom population to identify putative regulators underlying a high ascorbate phenotype in fruits. Among the ascorbate-enriched mutants, the family with the highest fruit ascorbate level (P17C5 line, up to 5 times the WT) strongly impaired flower development and produced seedless fruit. Without progeny, genetic characterization was performed by outcrossing the P17C5 line with S. Lycopersicum cv. M82. We successfully identified the mutation responsible for the high ascorbate trait in a cis-acting upstream open reading frame (uORF) that is 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-enrichment trait in tomato plants by phenotyping the original P17C5 EMS mutant, the population of outcrossed P17C5xM82 plants, and the CRISPR-mutated line. These studies revealed that a high ascorbate content is linked to impaired floral organ architecture, particularly anthers and pollen development, thus leading to male sterility. RNAseq analysis suggests that uORF-GGP1 acts as a regulator of ascorbate synthesis that maintains redox homeostasis to allow appropriate plant development.

Tocochromanols constitute the different forms of vitamin E (VTE), essential components of the human diet, and display a high membrane protectant activity. By combining interval mapping and genome-wide association studies (GWAS), we unveiled the genetic determinants of tocochromanol accumulation in tomato (Solanum lycopersicum) fruits. To enhance the nutritional value of this highly consumed vegetable, we dissected the natural intraspecific variability of tocochromanols in tomato fruits and genetically engineered their biosynthetic pathway. These analyses allowed the identification of a total of 25 quantitative trait loci interspersed across the genome pinpointing the chorismate–tyrosine pathway as a regulatory hub controlling the supply of the aromatic head group for tocochromanol biosynthesis. To validate the link between the chorismate–tyrosine pathway and VTE, we engineered tomato plants to bypass the pathway at the arogenate branch point. Transgenic tomatoes showed moderate increments in tocopherols (up to approximately 20%) and a massive accumulation of tocotrienols (up to approximately 3400%). Gene expression analyses of these plants reveal a trade-off between VTE and natural variation in chorismate metabolism explained by transcriptional reprogramming of specific structural genes of the pathway. By restoring the accumulation of alpha-tocotrienols (α-t3) in fruits, the plants produced here are of high pharmacological and nutritional interest. Fil: Burgos, Estanislao. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina Fil: de Luca, Maria Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina Fil: Diouf, Isidore. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: de Haro, Luis Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina Fil: Albert, Elise. Michigan State University; Estados Unidos. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Sauvage, Christopher. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; . Syngenta France SAS; Francia Fil: Tao, Zhao J.. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Bermudez Salazar, Luisa Fernanda. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Asís, Ramon. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; Argentina Fil: Nesi, Adriano N.. Universidade Federal de Viçosa.; Brasil Fil: Matringe, Michel. Universite Joseph Fourier; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Bréhélin, Claire. Universite Joseph Fourier; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Guiraud, Thomas. Universite de Bordeaux; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Ferrand, Carine. Universite de Bordeaux; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Atienza, Isabelle. Universite de Bordeaux; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Jorly, Joana. Universite de Bordeaux; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Mauxion, Jean P.. Universite de Bordeaux; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Baldet, Pierre. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; . Universite de Bordeaux; Francia Fil: Fernie, Alisdair R.. Institut Max Planck fur Molekulare Physiologie; Alemania Fil: Quadrana, Leandro. Inserm; Francia. Centre National de la Recherche Scientifique; Francia Fil: Rothan, Christophe. Universite de Bordeaux; Francia. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Causse, Mathilde. Centre Nouvelle - Aquitaine Bordeaux ; Instituto National de Recherches Agronomiques, Alimetation Et Environnement; Fil: Carrari, Fernando Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires; Argentina

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Highlight The two tomato GDP-D-mannose epimerase isoforms play specific roles in cell wall biosynthesis and plant development but participate similarly in ascorbate biosynthesis., GDP-D-mannose epimerase (GME, EC 5.1.3.18) converts GDP-D-mannose to GDP-L-galactose, and is considered to be a central enzyme connecting the major ascorbate biosynthesis pathway to primary cell wall metabolism in higher plants. Our previous work demonstrated that GME is crucial for both ascorbate and cell wall biosynthesis in tomato. The aim of the present study was to investigate the respective role in ascorbate and cell wall biosynthesis of the two SlGME genes present in tomato by targeting each of them through an RNAi-silencing approach. Taken individually SlGME1 and SlGME2 allowed normal ascorbate accumulation in the leaf and fruits, thus suggesting the same function regarding ascorbate. However, SlGME1 and SlGME2 were shown to play distinct roles in cell wall biosynthesis, depending on the tissue considered. The RNAi-SlGME1 plants harbored small and poorly seeded fruits resulting from alterations of pollen development and of pollination process. In contrast, the RNAi-SlGME2 plants exhibited vegetative growth delay while fruits remained unaffected. Analysis of SlGME1- and SlGME2-silenced seeds and seedlings further showed that the dimerization state of pectin rhamnogalacturonan-II (RG-II) was altered only in the RNAi-SlGME2 lines. Taken together with the preferential expression of each SlGME gene in different tomato tissues, these results suggest sub-functionalization of SlGME1 and SlGME2 and their specialization for cell wall biosynthesis in specific tomato tissues.

Beta3-adrenergic agonists have been considered as potent antiobesity and antidiabetic agents mainly on the basis of their beneficial actions discovered twenty years ago in obese and diabetic rodents. The aim of this work was to verify whether prolonged treatment with a beta3-adrenergic agonist known to stimulate lipid mobilisation, could promote desensitization of beta-adrenergic responses. Wistar rats and guinea pigs were treated during one week with CL 316243 (CL, 1 mg/kg/d) by implanted osmotic minipumps. In control animals, beta3-adrenergic agonists were lipolytic in rat but not in guinea pig adipocytes. CL-treatment did not alter body weight gain in both species, but reduced fat stores in rats. Lipolysis stimulation by forskolin was unmodified but responses to beta1-, beta2- and beta3-agonists were reduced in visceral or subcutaneous white adipose tissues of CL-treated rats. Similarly, the beta3-adrenergic-dependent impairment of insulin action on glucose transport and lipogenesis in rat adipocytes was diminished after CL-treatment. In rat adipocytes, [125I]ICYP binding and beta3-adrenoceptor mRNA levels were reduced after sustained CL administration. These findings show that CL 316243 exerts (beta3-adrenergic lipolytic and antilipogenic effects in rat adipocytes. These actions, which are likely involved in the fat depletion observed in rat, also lead to the desensitization of all beta-adrenergic responses. Therefore this desensitization, together with the lack of slimming action in guinea pig, seriously attenuates the usefulness of beta3-agonists as antiobesity agents, and may explain why such agonists have not been conducted to a widespread clinical use.

The aim of this study was to determine the effects of cafeteria diet containing control or elevated level of vitamin A on the expression of nuclear receptors in adipose tissue. Male Wistar rats were submitted to 3 experimental diets during 8 weeks, a standard diet and two hyper-energetic, hyperlipidic “cafeteria” diets containing normal (Caf) or higher (Caf+) vitamin A level. During the experiment, body weights and energy intakes were measured. At the end of the experimental period, subcutaneous adipose tissue (Swat) and all the fat mass were removed and weighted. Nuclear receptors mRNA levels of RARα, RARγ, RXRα, PPARγ were measured in the Swat by a real-time semi-quantitative RT-PCR method. We observed that energy intake of Caf+ and Caf groups was significantly higher than that of the control group. Despite a higher increase of the energy intake in the Caf group compared to the Caf+ group, no significant difference was observed in the body weight gain of the Caf+ compared to the Caf group. The Caf+ and Caf diets led to a significant increase of adipose tissue in cafeteria groups as observed in the Swat depot. The mRNA levels of PPARγ and RXRα were significantly increased in the Caf+ group as compared to control group, with a significant positive correlation between these two parameters. Expressions of RARα and RARγ were not modified in experimental groups compared to controls. In conclusion, 8-week exposure to cafeteria diets with normal and higher levels of vitamin A led to an increase of adiposity in rats, associated, only in the group fed with the higher vitamin A level cafeteria diet, with an increase of PPARγ and RXRα expressions in subcutaneous adipose tissue.

La methode mesurant la Capacite Antioxydante en Equivalent Trolox (TEAC) a ete utilisee pour determiner le potentiel antioxydant d'extraits vegetaux. Cette methode pratique est rapide et utilisable dans divers solvants pour un grand nombre de composes d'efficacites variees. La diminution de l'absorbance (% d'inhibition) de la solution de radical cation d'ARTS .+ traduit l'effet de l'echantillon antioxydant par comparaison avec une droite d'etalonnage realisee a partir du Trolox. L'aspect cinetique initial et l'equilibre thermodynamique de la reaction de piegeage du radical cation ARTS .+ , marqueur de l'efficacite de l'antioxydant, ont ete examines. L'evolution du potentiel antioxydant des echantillons a montre une stabilite variable lors de leur stockage a temperature ambiante pendant une semaine, ce qui ne permet pas d'envisager de differer les mesures du TEAC. Parmi les echantillons analyses seuls l'extrait de myrtille, le curcuma et surtout les extraits de pepins de raisin et de the vert sont a retenir pour leur pouvoir antioxydant et pour leur utilisation en agroalimentaire.

Amine degradation by adipocyte amine oxidases leads to the production of metabolites that interact with lipid and glucose metabolisms and their hormonal regulations. To further investigate these interactions, we determined the effect of a dietary amine, tyramine (TYR), on glycerol and lactate releases, respectively taken as indices of lipolytic and glycolytic activities of isolated adipocytes. Old male Wistar rats were used to prepare adipocytes by collagenase dissociation of retroperitoneal fat pads. The two tested doses of tyramine (10 microM and 1 mM) had no effect on basal glycerol release. On the other hand, TYR, at the highest dose tested (1 mM), weakly but significantly increased basal lactate release, which was elevated in adipocytes from old rats. Norepinephrine (NE), highly stimulated adipocyte lipolysis with a submaximal effect at 1 microM which was slightly but significantly inhibited by TYR 1 mM. Insulin 1 nM (INS) also poorly inhibited the NE-stimulated lipolysis in adipocytes isolated from old rats. TYR was able to potentiate the poor antilipolytic efficiency of INS. Under similar conditions, a high dose of NE greatly reduced lactate production and TYR (1 mM) reversed this inhibition of lactate release. INS was also able to totally reverse the inhibitory effect of NE on lactate release, but there was no potentiation between insulin and tyramine effects. It can be concluded that high doses of TYR interact with norepinephrine and insulin, at least on the control of glycerol and lactate release, by counteracting catecholamine effects and by mimicking insulin actions.

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Potassium sorbate can undergo oxidation to form carbonyl moieties and cause browning. This investigation studied the fate of the compounds produced by auto-oxidation of potassium sorbate and measured the browning in the presence of amines. Experimental plans in which four factors were combined (temperature, oxygen, amine and light) led to the observation that the interaction between oxygen and high temperature (75 degrees C) favoured browning, independently of the presence of amine. At 4 degrees C, the amine seemed to cause a decrease in the proportion of carbonyl-containing compounds which would appear to participate in carbonyl-amine reactions. At 75 degrees C, the amine forms adducts with the potassium sorbate. In parallel, high temperature favours auto-oxidation reactions that produce carbonyls. GC/MS and NMR analysis of the reaction products of potassium sorbate/amine mixtures led to the identification of cyclic products.

Sorbic acid has a system of conjugated double bonds which makes it able to undergo nucleophilic addition reactions with certain functions. The interactions between sorbic acid and amine functions present in the endogenous constituents of food were quantified. The formation of new products was demonstrated and the underlying mechanisms studied using ethyl sorbate and various amines. HPLC, GC, GC-SM and NMR analyses of the reaction mixtures enabled the products to be isolated and identified. The addition reactions led, at 20 degrees C, to linear monoadducts and, at 50 degrees C and 80 degrees C, to cyclic derivatives resulting from double addition.

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International audience; Tomato is currently the model plant for fleshy fruit development and for Solanaceae species. Recent genomic approaches including transcriptome, proteome and metabolome analyses and genetic mapping have produced a wealth of candidate genes whose function needs to be assessed. The recent development in model and crop plants of TILLING (Targeting Induced Local Lesions IN Genomes), which reveals allelic series corresponding to several independent point mutations, and the current availability of deep sequencing tools further increase the interest of generating artificially-induced genetic diversity in tomato. We describe here the generation and use of EMS (ethyl methanesulfonate) tomato mutants in the miniature cultivar Micro-Tom and provide as example the identification of new fruit size and morphology mutants. We further propose new deep sequencing-based strategies for the discovery of mutations underlying phenotypic variations observed in mutant collections that will considerably increase the interest of exploiting Micro-Tom mutant collections for gene discovery in tomato.

International audience; Besides being a model for fleshy fruits and Solanaceae species, tomato represents one of the main sources of ascorbate (vitamin C) in human diet in many parts of the world. Ascorbate fulfills various roles in plants due to its antioxidant potential and to its connection with other metabolic pathways e. g. cell wall biosynthesis. Among the functional genomic tools recently developed in tomato, EMS (ethyl methanesulfonate) mutant collections provide an opportunity for identifying allelic series of mutations in target genes by TILLING (Targeting Induced Local Lesions IN Genomes). We describe here the use of tomato EMS mutant collections in the miniature cv. Micro-Tom for the discovery of allelic variants in three ascorbate biosynthetic genes encoding the GDP-D-mannose pyrophosphorylase (GMP), the GDP-D-mannose epimerase (GME) and the GDP-L-galactose phosphorylase (GGP) respectively. We report on the discovery of several missense, truncation and splice junction mutations in these genes affecting plant ascorbate content to various levels, and show that several tomato mutant lines with strongly reduced ascorbate content undergo severe bleaching upon exposure to high light intensity.

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International audience; Tomato is an essential crop in terms of economic importance and nutritional quality. In France, the third most important region for tomato (Solanum lycopersicum L.) production is Aquitaine where the major part of production is now grown soilless under greenhouse conditions with harvest from March to November. Tomato fruit quality at harvest is a direct function of its metabolite content at that time. The aim of this work was to use a global approach to characterize changes in the fruit organoleptic quality at harvest under commercial culture conditions during an entire season for two varieties and two different fertilization practices (with or without recycling of the nutrient solution) for one variety. Absolute quantification data of 32 major compounds in fruit without seeds were obtained through untargeted (proton nuclear magnetic resonance, 1H-NMR) quantitative profiling. These data were complemented by colorimetric analysis of ascorbate and total phenolics. They were analyzed with chemometric approaches. Principal component analysis (PCA) or partial least square analyses (PLS) revealed more discriminant metabolites for season than for variety and showed that nutrient solution recycling had very little effect on fruit composition. These tendencies were confirmed with univariate analyses. 1H-NMR profiling complemented with colorimetric analyses therefore provided a diagnostic tool to follow the changes in organoleptic and nutritional quality of tomato. In addition the quantitative information generated will help to increase our knowledge on the mechanisms of plant response to environmental modifications.

In order to study the effects of dietary lipids and vitamin A on the development of adipose tissues, young rats were submitted for 8 d to a control or to two cafeteria diets with normal (Caf) or higher (Caf+) vitamin A levels. Retinoid (retinoic acid receptor (RAR) α, RARγ, retinoid X receptor (RXR) α) and fatty acid (PPARγ) receptor mRNA was measured in the subcutaneous white adipose tissue (Swat) and in isolated mature adipocytes by RT-PCR. The stroma vascular fraction was culturedin vitroto test the capacities of the adipocyte precursors to proliferate and differentiate. The Caf diet enriched in vitamin A resulted in an increased adiposity, due to increased adipocyte hypertrophy. This was concomitant with a lower expression of RARα and RARγ mRNA ( − 34·6 and − 38·6 %) and a higher expression of PPARγ (+59 %) in the Swat and, to a less extent, in isolated adipocytes. Positive correlations were obtained between PPARγ mRNA and Swat weights and between PPARγ and RXRα mRNA. By contrast, RARγ mRNA and Swat masses were negatively correlated. The adipocyte precursors from Caf+ Swat proliferated more,in vitro, at the beginning of the culture. This difference progressively disappeared and was totally absent after 8 d of culture, but with a higher percentage of differentiated preadipocytes (+80·3 %) in the Caf+ group. In conclusion, lipids and vitamin A act synergistically on the normal growth of the adipose tissue in young rats, concomitant with an imbalance in the pattern of the nuclear receptors. These changes influence the early normal development of the endogenous adipocyte precursors.

Oxidation control is necessary to manage the evolution of complex biological system, particularly in food whose degradation could have consequences on food security. After description of context and oxidation mechanisms, several analytical methods to evaluate the additive antioxidant potential are presented. This evaluation is performed either by quantification of products (in particular hydroperoxydes) using direct or indirect photometric techniques and chemical titration with suitable reactants or on the effectiveness to trap free radicals with modelized systems that can generate them. Methods based on the comparison of radical trapping ability between an additive and Trolox (particularly Trolox(R) equivalent antioxydant capacity, TEAC) can be applied to many products whatever the hydrophily or the hydrophobia of the medium.

Sorbic acid as well as potassium and calcium sorbate (E202 and E203) are legally used as preservatives in numerous processed foods. Owing to its system of conjugated double bonds, sorbic acid is likely to undergo a nucleophilic attack, which may turn it into mutagenic products. The cyclic derivatives resulting from a double addition reaction between sorbic acid and various amines at two different temperatures (50 degrees C and 80 degrees C) have been analysed. A genotoxicity study has been performed with HeLa cells and plasmid DNA. A mutagenesis study has been carried out by using the Ames test. A SOS spot test and a cytotoxicity study have been realised as well. The results showed that the products involved exhibited neither mutagenic nor genotoxic activities.

Sorbic acid (E200) and its salts (potassium and calcium sorbate: E202 and E203) are allowed for use as preservatives in numerous processed foods. Sorbic acid has a conjugated system of double bonds which makes it susceptible to nucleophilic attack, sometimes giving mutagenic products. Under conditions typical of food processing (50-80 degrees C), we analyzed the cyclic derivatives resulting from a double addition reaction between sorbic acid and various amines. Mutagenesis studies, involving the Ames test and genotoxicity studies with HeLa cells and plasmid DNA, showed that none of the products studied presented either mutagenic or genotoxic activities.

Sorbic acid has a system of conjugated double bonds which makes it able to undergo nucleophilic addition reactions with certain functions. The interactions between sorbic acid and an amine present in the endogenous constituents of food were quantified. We demonstrated the formation of new products and studied the underlying mechanisms using ethyl sorbate and various amines. HPLC, GC, GC-SM and NMR analyses of the reaction mixes enabled the isolation and identification of the products. The addition reactions led, at 20 degrees C, to linear monoadducts and, at 50 degrees C, to cyclic derivatives resulting from double addition. Mutagenesis studies, involving Ames test and genotoxicity studies with HeLa cells and on plasmid DNA, in cyclic interaction products, showed that none of the products studied presented neither mutagenic nor genotoxic activities.

Maîtriser l’oxydation est indispensable pour gérer l’évolution des systèmes biologiques dans leur complexité, en particulier dans le cas des aliments dont la dégradation peut avoir des conséquences en sécurité alimentaire. Les différentes méthodes d’évaluation de l’activité antioxydante d’un additif alimentaire sont présentées après examen du contexte et des mécanismes d’oxydation. L’activité anti-oxydante est évaluée soit par le dosage des produits formés (en particulier des hydroperoxydes) par des techniques photométriques plus ou moins directes, soit par la mesure de l’efficacité du composé à piéger des radicaux libres. Les méthodes comparant le piégeage d’un additif avec celui d’un anti-oxydant de référence, le Trolox®, sont applicables à des produits variés quelle que soit l’hydrophilie ou l’hydrophobie du milieu., Oxidation control is necessary to manage the evolution of complex biological system, particularly in food whose degradation could have consequences on food security. After description of context and oxidation mechanisms, several analytical methods to evaluate the additive antioxidant potential are presented. This evaluation is performed either by quantification of products (in particular hydroperoxydes) using direct or indirect photometric techniques and chemical titration with suitable reactants or on the effectiveness to trap free radicals with modelized systems that can generate them. Methods based on the comparison of radical trapping ability between an additive and Trolox (particularly Trolox® equivalent antioxydant capacity, TEAC) can be applied to many products whatever the hydrophily or the hydrophobia of the medium.

International audience

International audience; Abstract This chapter focuses on three vitamins for which fleshy fruits are important sources in the human diet: two fat-soluble vitamins, the provitamin A carotenoids, which are precursors of vitamin A (retinoids), and vitamin E (tocopherols), and the water-soluble vitamin C (ascorbate). In the first part of the chapter, a general overview is given for each vitamin: its physiological role in plants, the biosynthetic pathways in fleshy fruits and regulation by genetic factors, and environmental cues in terms of fruit development and during postharvest storage. In the second part, the various strategies currently being undertaken to improve the vitamin content of fleshy fruits are reviewed, such as genetic engineering and breeding. The rapid acquisition of genome sequences and high-density-marker genetic maps in fleshy fruit species will considerably improve the speed and efficiency of the identification of genes underlying fruit vitamin quantitative trait loci and, subsequently, the transfer of the alleles of interest to elite varieties.