Potential for Ethanol Vapours to Limit Table Grape Berry Shatter and to Limit Ethylene Evolution from Clusters

We have shown previously that ethanol vapours (given by 2 ml per kg of grapes) can prevent Botrytis development and stem browning, two of the major problems in postharvest quality of table grapes. In the present paper, we will give emphasis to preliminary results about (i) the role of ethanol vapours in the inhibition of berry shatter and (ii) the control of ethylene evolution from grapes bunches by ethanol vapours and the link to the control of Botryti

Chloroplast to chromoplast transition in tomato fruit: spectral confocalmicroscopy analyses of carotenoids and chlorophylls in isolated plastids and time-lapse recording on intact live tissue

During evolution, chromoplasts have emerged as plastid structures which accumulate pigments to facilitate flower pollination and seed dispersal of fleshy fruit. There is good evidence that chromoplasts derive from chloroplasts (Pyke, 2007), even if nobody has ever recorded this transition. Structural changes occurring during chloroplast to chromoplast transition have been described in fleshy fruit by electron microscopy primarily in tomato (Rosso, 1968; Harris and Spurr, 1969) and in bell pepper (Spurr and Harris, 1968). During the differentiation process controlled breakdown of chlorophyll and disruption of the thylakoid membrane occurred, concomitant with an increase in the aggregation of carotenoids. Different carotenoid-accumulating bodies have been described, including plastoglobules, crystalline and microfibrillar structures, and internal membranous structures

Metabolic and molecular events occurring during chromoplast biogenesis

Chromoplasts are nonphotosynthetic plastids that accumulate carotenoids. They derive from other plastid forms, mostly chloroplasts. The biochemical events responsible for the interconversion of one plastid form into another are poorly documented. However, thanks to transcriptomics and proteomics approaches, novel information is now available. Data of proteomic and biochemical analysis revealed the importance of lipid metabolism and carotenoids biosynthetic activities. The loss of photosynthetic activity was associated with the absence of the chlorophyll biosynthesis branch and the presence of proteins involved in chlorophyll degradation. Surprisingly, the entire set of Calvin cycle and of the oxidative pentose phosphate pathwaypersisted after the transition from chloroplast to chromoplast. The role of plastoglobules in the formation and organisation of carotenoid-containing structures and that of the Or gene in the control of chromoplastogenesis are reviewed. Finally, using transcriptomic data, an overview is given the expression pattern of a number of genes encoding plastid-located proteins during tomato fruit ripening

Adaptation of the base-paired double-helix molecular architecture to extreme pressure

The behaviour of the d(GGTATACC) oligonucleotide has been investigated by X-ray crystallography at 295 K in the range from ambient pressure to 2 GPa (∼20 000 atm). Four 3D-structures of the A-DNA form (at ambient pressure, 0.55, 1.09 and 1.39 GPa) were refined at 1.60 or 1.65 Å resolution. In addition to the diffraction pattern of the A-form, the broad meridional streaks previously explained by occluded B-DNA octamers within the channels of the crystalline A-form matrix were observed up to at least 2 GPa. This work highlights an important property of nucleic acids, their capability to withstand very high pressures, while keeping in such conditions a nearly invariant geometry of base pairs that store and carry genetic information. The double-helix base-paired architecture behaves as a molecular spring, which makes it especially adapted to very harsh conditions. These features may have contributed to the emergence of a RNA World at prebiotic stage

Sl-ARF4,an Auxin Response Factor involved in the control of sugar metabolism during tomato fruit development

Successful completion of fruit developmental programs depends on the interplay between multiple phytohormones. However,besides ethylene, the impact of other hormones on fruit quality traits remains elusive. A previous study has shown that downregulation of SlARF4, a member of the tomato (Solanum lycopersicum) auxin response factor (ARF) gene family, results in a darkgreen fruit phenotype with increased chloroplasts (Jones et al., 2002). This study further examines the role of this auxin transcriptional regulator during tomato fruit development at the level of transcripts, enzyme activities, and metabolites. It is noteworthy that the dark-green phenotype of antisense SlARF4-suppressed lines is restricted to fruit, suggesting that SlARF4 controls chlorophyll accumulation specifically in this organ. The SlARF4 underexpressing lines accumulate more starch at early stages of fruit development and display enhanced chlorophyll content and photochemical efficiency, which is consistent with the idea that fruit photosynthetic activity accounts for the elevated starch levels. SlARF4 expression is high in pericarp tissues of immature fruit and then undergoes a dramatic decline at the onset of ripening concomitant with the increase in sugar content. The higher starch content in developing fruits of SlARF4 down-regulated lines correlates with the up-regulation of genes and enzyme activities involved in starch biosynthesis, suggesting their negative regulation by SlARF4. Altogether, the data uncover the involvement of ARFs in the control of sugar content, an essential feature of fruit quality, and provide insight into the link between auxin signaling, chloroplastic activity, and sugar metabolism in developing fruit

Functional characterization of SlscADH1, a fruit-ripening associated short-chain alcohol dehydrogenase of tomato

A tomato short-chain dehydrogenase-reductase (SlscADH1) is preferentially expressed in fruit with a maximum expression at the breaker stage while expression in roots, stems, leaves and flowers is very weak. It represents a potential candidate for the formation of aroma volatiles by interconverting alcohols and aldehydes. The SlscADH1 recombinant protein produced in Escherichia coli exhibited dehydrogenase-reductase activity towards several volatile compounds present in tomato flavour with a strong preference for the NAD/NADH co-factors. The strongest activity was observed for the reduction of hexanal (Km = 0.175 mM) and phenylacetaldehyde (Km = 0.375 mM) in the presence of NADH. The oxidation process of hexanol and 1-phenylethanol was much less efficient (Kms of 2.9 and 23.0 mM, respectively), indicating that the enzyme preferentially acts as a reductase. However activity was observed only for hexanal, phenylacetaldehyde, (E)-2-hexenal and acetaldehyde and the corresponding alcohols. No activity could be detected for other aroma volatiles important for tomato flavour, such as methyl-butanol/methyl-butanal, 5-methyl-6-hepten-2-one/5-methyl-6-hepten-2-ol, citronellal/citronellol, neral/nerol, geraniol. In order to assess the function of the SlscADH1 gene, transgenic plants have been generated using the technique of RNA interference (RNAi). Constitutive down-regulation using the 35S promoter resulted in the generation of dwarf plants, indicating that the SlscADH1 gene, although weakly expressed in vegetative tissues, had a function in regulating plant development. Fruitspecific down-regulation using the 2A11 promoter had no morphogenetic effect and did not alter the aldehyde/alcohol balance of the volatiles compounds produced by the fruit. Nevertheless, SlscADH1-inhibited fruit unexpectedly accumulated higher concentrations of C5 and C6 volatile compounds of the lipoxygenase pathway, possibly as an indirect effect of the suppression of SlscADH1 on the catabolism of phospholipids and/or integrity of membranes

Programme de recherches interdisciplinaires « Vérité et fiction »

Stéphane Breton, Jean-Paul Colleyn, André Gunthert, Jean-Claude Penrad, Annick Bouleau, Sabine Chalvon, Daniel Dayan, Renaud Dulong, Éliane de Latour, Catarina Pasqualino, Dominique Pasquier, Marc-Henri Piault, Jean-Pierre Bertin-Maghit, Jacqueline Chervin, Emmannuel Grimaud, Roger Odin, Laurence Allard Allard, Gilles Saussier, Elodie Perreau Nous avons poursuivi nos travaux sur la tension (majeure), entre la vérité et la fiction dans les formes d’expression audiovisuelles. Roger Odin (Univer..

Programme de recherches interdisciplinaires « Vérité et fiction »

Stéphane Breton, Jean-Paul Colleyn, André Gunthert, Jean-Claude Penrad, Annick Bouleau, Sabine Chalvon, Daniel Dayan, Renaud Dulong, Éliane de Latour, Catarina Pasqualino, Dominique Pasquier, Marc-Henri Piault, Jean-Pierre Bertin-Maghit, Jacqueline Chervin, Emmannuel Grimaud, Roger Odin, Laurence Allard Allard, Gilles Saussier, Elodie Perreau Nous avons poursuivi nos travaux sur la tension (majeure), entre la vérité et la fiction dans les formes d’expression audiovisuelles. Roger Odin (Univer..

Technologie des Hautes Pressions

pour le champs 'auteurs', les Directeurs de publications apparaissent en premier puis le Directeur de collection.International audienceP. 7|Préface / J. C Chervin et J. Peyronneau|P. 9|Chapitre I, Enceintes pour hautes pressions hydrostatiques / Jacques Roux et Michel Pichavant|P. 37|Chapitre II, Appareils pour haute pression de 1 à 10 GPa en milieu solide / Jean-Michel Léger|P. 57|Chapitre III, Les systèmes multi-enclumes / Max Schmidt et Jean-Pierre Petitet|P. 83|Chapitre IV, Dispositifs à enclumes opposées / Jean-Michel Besson|P. 117|Chapitre V, Les hautes pressions dynamiques, systèmes de génération et d'analyse / Dominique Vrel et Tsutomu Mashimo|P. 149|Chapitre VI, Modélisation des contraintes dans les ensembles sous pression / D. Leguillon|P. 187|Programmes des communications orales|P. 193|Programmes des communications affiché

La transition chloroplaste-chromoplaste dans le fruit de tomate

L'un des phénomènes les plus importants survenus pendant la maturation du fruit de tomate est le changement de couleur du vert au rouge. Ce changement a lieu dans les plastes et correspond à la différenciation des plastes photosynthétiques, les chloroplastes, en plastes non-photosynthétiques qui accumulent des caroténoïdes, les chromoplastes. Dans cette thèse, nous présentons d'abord une introduction bibliographique sur le domaine de la transition chloroplaste-chromoplaste, en décrivant les modifications structurales et physiologiques qui se produisent pendant la transition. Puis, dans le premier chapitre, nous présentons des observations microscopiques de plastes isolés à trois stades de mûrissement, puis des enregistrements en temps réel de la fluorescence des pigments sur les tranches de fruits de tomate. Il a été possible de montrer que la transition chloroplaste-chromoplaste était synchrone pour tous les plastes d'une seule cellule et que tous les chromoplastes proviennent de chloroplastes préexistants. Dans le deuxième chapitre, une approche protéomique quantitative de la transition chloroplaste-chromoplaste est présentée, pour identifier les protéines différentiellement exprimées. Le traitement des données a identifié 1932 protéines parmi lesquelles 1529 ont été quantifiées par spectrométrie de masse. Les procédures de quantification ont ensuite été validées par WESTERN blot de certaines protéines. La chromoplastogénèse comprend les changements métaboliques suivants : diminution de l'abondance des protéines de réaction à la lumière et du métabolisme des glucide, et l'augmentation de la biosynthèse des terpénoïdes et des protéines de stress. Ces changements sont couplés à la rupture de la biogenèse des thylakoïdes, des photosystèmes et des composants de production d'énergie, et l'arrêt de la division des plastes. Dans le dernier chapitre nous avons utilisé la lincomycine, un inhibiteur spécifique de la traduction à l'intérieur des plastes, afin d'étudier les effets sur la maturation des fruits et sur l'expression de gènes nucléaires impliqués dans la maturation. Les résultats préliminaires indiquent que l'inhibition de la traduction des protéines dans les plastes affecte la maturation du fruit en réduisant l'accumulation de caroténoides. L'expression de plusieurs gènes nucléaires a été modifiée mais une relation claire avec le phénotype altéré de maturation n'a pas pu être établie. Au total, notre travail donne de nouveaux aperçus sur le processus de différenciation chromoplaste et fournit des données nouvelles ressources sur le protéome plasteOne of the most important phenomenons occurring during tomato fruit ripening is the color change from green to red. This change takes place in the plastids and corresponds to the differentiation of photosynthetic plastids, chloroplasts, into non photosynthetic plastids that accumulate carotenoids, chromoplasts. In this thesis we first present a bibliographic introduction reviewing the state of the art in the field of chloroplast to chromoplast transition and describing the structural and physiological changes occurring during the transition. Then, in the first chapter we present an in situ real-time recording of pigment fluorescence on live tomato fruit slices at three ripening stages. By viewing individual plastids it was possible to show that the chloroplast to chromoplast transition was synchronous for all plastids of a single cell and that all chromoplasts derived from pre-existing chloroplasts. In chapter two, a quantitative proteomic approach of the chloroplast-to-chromoplast transition is presented that identifies differentially expressed proteins. Stringent curation and processing of the data identified 1932 proteins among which 1529 were quantified by spectral counting. The quantification procedures have been subsequently validated by immune-blot evaluation of some proteins. Chromoplastogenesis appears to comprise major metabolic shifts (decrease in abundance of proteins of light reactions and carbohydrate metabolism and increase in terpenoid biosynthesis and stress-related protein) that are coupled to the disruption of the thylakoid and photosystems biogenesis machinery, elevated energy production components and loss of plastid division machinery. In the last chapter, we have used lincomycin, a specific inhibitor of protein translation within the plastids, in order to study the effects on fruit ripening and on the expression of some ripening-related nuclear genes. Preliminary results indicate that inhibiting protein translation in the plastids affects fruit ripening by reducing the accumulation of carotenoids. The expression of several nuclear genes has been affected but a clear relationship with the altered ripening phenotype could not be established. Altogether, our work gives new insights on the chromoplast differentiation process and provides novel resource data on the plastid proteomeTOULOUSE-ENSAT-Documentation (315552324) / SudocSudocFranceF