Activities of polyamine oxidases and diaminopropane contents during flowering of Vinis vinifera L.

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Analyse des polyamines conjuguées aux acides hydroxycinnamiques dans les fleurs de vigne et les baies de raisin

La comparaison des deux cépages Merlot et Cabernet-Sauvignon en plein champ montre que les polyamines conjuguées aux acides hydroxycinnamiques peuvent être considérées comme des marqueurs du début de la floraison et de la croissance du fruit. Des polyamines conjuguées aux acides hydroxycinnamiques sont présentes en grande quantité dans les organes reproducteurs des boutons floraux et des fleurs. Les ovaires renferment essentiellement des polyamines conjuguées insolubles dans l'eau alors que dans les anthères s'accumulent des composés basiques solubles dans l'eau comme principalement le para-coumaryldiaminopropane. Après la floraison, les teneurs en polyamines conjuguées chutent considérablement pour s'accumuler à nouveau dans les jeunes baies, uniquement sous leur forme soluble dans l'eau et liée à l'acide férulique. L'intervention de ces substances dans les mécanismes liés au contrôle de la reproduction chez la vigne est discutée.Hydroxycinnamic acid amines in flowers and berries of Vitis viniferaThe determination of phenolamines in flowers and berries of field-grown Vitis vinifera (cv. Cabernet-Sauvignon and Merlot) shows that these compounds can be considered as valuable markers of the onset of flowering and growth of berries. Hydroxycinnamic acid amines are found in large amounts in the reproductive organs. The ovaries contain neutral phenolamines and the anthers the basic compound para-coumaryldiaminopropane. After flowering, hydroxycinnamic acid amines rapidly and dramatically decreased. In young berries, levels of polyamines increased; they were found to be soluble in water and conjugated with ferulic acid. The possible role of these molecules in processes controlling reproduction of grape is discussed

Les boutures fructifères de vigne : validation d'un modèle d'étude de la physiologie de la vigne. 2 Etude du développement de la grappe

National audienc

Les boutures fructifères de vigne : validation d'un modèle d'étude de la physiologie de la vigne. 1 Principales caractéristiques de l'appareil végétatif

National audienc

Influence d'un apport excessif d'azote sur les teneurs en polyamines, libres et conjuguées, des limbes des feuilles de vigne et des baies de raisin au cours de leur développement

National audienc

Effects of potassium nutrition on polyamine content of various organs of fruiting cuttings of Vitis vinifera L. cv. Cabernet Sauvignon

International audienc

Proteome analysis of grape skins during ripening

International audienceThe characterization of proteins isolated from skin tissue is apparently an essential parameter for understanding grape ripening as this tissue contains the key compounds for wine quality. It has been particularly difficult to extract proteins from skins for analysis by two-dimensional electrophoresis gels and, therefore, a protocol for this purpose has been adapted. The focus was on the evolution of the proteome profile of grape skin during maturation. Proteome maps obtained at three stages of ripening were compared to assess the extent to which protein distribution differs in grape skin during ripening. The comparative analysis shows that numerous soluble skin proteins evolve during ripening and reveal specific distributions at different stages. Proteins involved in photosynthesis, carbohydrate metabolisms, and stress response are identified as being over-expressed at the beginning of colour-change. The end of colour-change is characterized by the over-expression of proteins involved in anthocyanin synthesis and, at harvest, the dominant proteins are involved in defence mechanisms. In particular, increases in the abundance of different chitinase and ß-1,3-glucanase isoforms were found as the berry ripens. This observation can be correlated with the increase of the activities of both of these enzymes during skin ripening. The differences observed in proteome maps clearly show that significant metabolic changes occur in grape skin during this crucial phase of ripening. This comparative analysis provides more detailed characterization of the fruit ripening process

Assessment of ontogenic resistance to Botrytis cinerea in grape berries and effect of water availability

International audienc

Grape berry skin features related to ontogenic resistance to Botrytis cinerea

International audienceThis work investigated the structural and biochemical changes during grape berry development which account potentially for the onset and increase in susceptibility to Botrytis cinerea. Using the cv. Sauvignon blanc, we quantified at seven developmental growth stages from herbaceous to over-mature berries: (1) fruit ontogenic resistance using three strains (II-transposa), (2) the morphological and maturity fruit characteristics and (3) preformed biochemical compounds located in the berry skin. From the mid-colour change stage onwards, susceptibility of unwounded fruit increased sigmoidally in both rot and sporulation severities at the berry surface. A principal component analysis identified a very close connection between fruit susceptibility and the level of fruit maturity. Berry susceptibility was significantly and positively correlated with the phenolic compounds in the skin cell walls and negatively correlated with the total tannin content in the skin and with water activity (Aw) at the fruit surface. On the berry, Aw decreased from 0.94 at bunch closure to 0.89 at berry maturity, with a relatively low value (0.90) at the stage of mid-colour change. Using artificial media, different Aw levels led to significant differences in mycelial growth (Aw ≤0.95 resulted in the lowest growth rate ≤0.34 mm day−1). Thus, besides the level of fruit maturity, both water activity on the fruit and the total tannin content in the skin may affect fungal growth and berry colonisation. The potential of these variables for use as indicators of grape berry susceptibility as well as associated mechanisms for the development of disease are discussed