Wine chemical compositions, which result from a complex interplay between environmental factors, genetic factors, and viticultural practices, have mostly been studied using targeted analyses of selected families of metabolites. Detailed studies have particularly concerned volatile and polyphenolic compounds because of their acknowledged roles in the organoleptic and therapeutic properties. However, we show that an unprecedented chemical diversity of wine composition can be unraveled through a nontargeted approach by ultrahigh-resolution mass spectrometry, which provides an instantaneous image of complex interacting processes, not easily or possibly resolvable into their unambiguous individual contributions. In particular, the statistical analysis of a series of barrel-aged wines revealed that 10-year-old wines still express a metabologeographic signature of the forest location where oaks of the barrel in which they were aged have grown.diagenesis ͉ Fourier transform ͉ ion cyclotron resonance ͉ metabolite ͉ mass spectrometry

The two most common oak species in western Europe, Quercus robur and Quercus petraea, display different ecological behaviours, particularly with respect to their responses to drought. The ecophysiological basis of this niche difference is not understood well. Here we test the hypothesis that these two species present distinct water use efficiencies (WUEs), using the carbon isotope discrimination approach. Leaves and 13 dated ring sequences were sampled in 10 pairs of adult trees growing side by side. Carbon isotope composition was measured on cellulose extracts. In addition, relationships between carbon isotope discrimination and wood anatomy were assessed at the tree level. Quercus robur displayed a 1·0‰ larger isotopic discrimination than Q. petraea, and therefore a lower intrinsic WUE ( ----13%). This interspecific difference of isotopic discrimination was quite stable with time and independent of tree radial growth and climate fluctuations. A strong positive correlation was observed between average tree values of earlywood vessel surface area and 13 C isotopic discrimination. This correlation was even higher with 13 C of the 1976 dry year ( r = 0·86). These observations led to the hypothesis that hydraulic properties of xylem could exert a constraint on leaf gas exchange, resulting in a larger WUE for individuals with smaller vessel cross-section area.

The interspecific variability of wood anatomy between the two major oak species Quercus robur L. and Quercus petraea (Matt.) Liebl. is still largely unknown. However, anatomy strongly influences the technological properties of wood and the ecophysiological functioning of trees. Moreover, identification of oak wood species is a long-standing challenge and important for many purposes. In the Cîteaux Forest (Burgundy), 58 oaks from 14 mixed stands were sampled for wood anatomy characterization. Image analyses of four ring radiographies per tree were carried out. Shape, size, and proportion of tissues (earlywood vessels, fiber, parenchyma, and latewood vessels) were characterized, taking into account cambial age and ring-width effects. Taxonomic status of the trees was assessed by foliar morphology analysis. Significant differences in numerous anatomical features appeared between the two species. The surface proportion of earlywood vessels (the proportion of total ring surface area taken up by these vessels), the number of earlywood vessels, and the size and surface proportion of fiber zones were among the largest. The diameter and shape of earlywood vessels did not differ between the two species. A bivariate discriminant function reached a 78% rate of success for species recognition. However, a much clearer foliar morphology gap existed between the two species. At the intraspecific level, linear correlations between anatomical and morphological variables were significant for a few variables only. Nevertheless, for each species, trees displaying an atypical wood anatomy were also less morphologically representative. Technological and ecophysiological implications of these results are discussed. In mixed stands, hybridization introgression between the two species could explain the large anatomical overlap. Thus, anatomical discrimination between the two oak species may be easier in pure stands. Finally, a practical identification key is given. Résumé : La variabilité inter-spécifique de l'anatomie du bois des deux principaux chênes de la forêt européenne (Quercus robur L. et Quercus petraea (Matt.) Liebl.) est encore paradoxalement peu connue. Pourtant, l'anatomie conditionne pour une large part les propriétés technologiques du bois et le fonctionnement écophysiologique des arbres. La possibilité d'identifier l'espèce à partir d'échantillons de bois offrirait aussi une large gamme d'applications. Quatorze peuplements mélangés de chênes pédonculé et sessile de la forêt de Cîteaux (Bourgogne) ont été échantillonnés (58 chênes au total). Par analyse d'images radiographiques de carottes de sondage, on a caractérisé la forme, la taille et la proportion des différents tissus (gros vaisseaux, fibres, parenchyme et petits vaisseaux) de quatre cernes par arbre, en contrôlant les effets âge et largeur de cerne. Le statut taxonomique des arbres a été précisé par analyse de la morphologie foliaire. Nous mettons en évidence, entre autres, des différences très significatives entre espèces pour le nombre et la proportion surfacique ...

Heartwood ellagitannins and volatile extractives were studied by high-pressure liquid chromatography and gas chromatography -mass spectrometry after extraction of wood samples taken from 54 mature trees of pedunculate oak (Quercus robur L.) and sessile oak (Quercus petraea (Matt.) Liebl.) from 14 mixed stands located in the forest of Cîteaux (Bourgogne). These same trees had been previously subject to detailed study of leaf morphology and wood anatomy. Over 50 compounds, of diverse chemical types, were identified in the wood extracts and over 30 of these compounds were quantified. No species-specific extractives were identified, but the amounts of ellagitannins and a small number of volatile compounds, including cis-and trans-β-methyl-γ-octalactone isomers, were found to vary significantly between the two species. Multivariate analyses of these extractives allowed the classification of samples according to species, although less distinctly than similar analyses using leaf morphological characteristics. No strong intraspecific correlations between chemical constituents and anatomical or morphological characteristics were found that were common for both species. Nonetheless, sessile oaks displaying atypical wood anatomy were also less morphologically and chemically representative of their species. Trees possessing the lowest levels of cis-and trans-β-methyl-γ-octalactone are found to be those with a morphology the least distinct of either species.Résumé : La composition en ellagitannins et en composés volatils du duramen de chêne a été étudiée par chromatographie liquide à haute pression et par chromatographie gazeuse -spectrométrie de masse sur 54 chênes pédonculés (Quercus robur L.) et rouvres (Quercus petraea (Matt.) Liebl.) adultes sondés dans 14 peuplements mixtes de la forêt de Cîteaux (Bourgogne). Ces arbres ont déjà fait l'objet d'une étude de la morphologie foliaire et des caractéristiques anatomiques du bois. Plus de 50 composés, appartenant à diverses familles chimiques, ont été identifiés dans les extraits de bois et plus de 30 de ces composés ont été quantifiés. Aucun composé spécifique de l'espèce n'a été trouvé, mais les teneurs en ellagitannins et en quelques substances volatiles incluant les isomères cis-et trans-β-méthyl-γ-octalactone varient significativement entre les deux espèces. L'analyse multivariable effectuée sur les composés chimiques discriminants permet de séparer globalement les arbres en fonction de l'espèce, toutefois moins distinctement que l'analyse multivariable effectuée sur les caractères de la morphologie foliaire. Au niveau intraspécifique, les corrélations entre les substances chimiques et les caractéristiques morphologiques ou anatomiques sont faibles pour les deux espèces. Cependant, les chênes rouvres qui présentent une anatomie atypique sont également les moins caractéristiques de l'espèce du point de vue de la morphologie et de la chimie. Les arbres qui possèdent les plus faibles teneurs en cis-et trans-β-méthyl-γ-octalactone sont ceux qui présentent la morphologie la mo...

A non-targeted, ultra-high-resolution mass spectrometric, direct analysis of oak-wood extracts from two species (Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra-high-resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea, respectively, as corroborated by both FTMS and NMR data. For the first time, it is shown that oak woods can also be discriminated on the basis of hundreds of forest-related compounds, and particular emphasis is put on sessile oaks from the Tronçais forest, for which sugars are significantly discriminant. Despite the higher complexity and diversity of wine metabolites, forest-related compounds can also be detected in wines aged in related barrels. It is only by using these non-targeted analyses that such innovative results, which reveal specific chemodiversities of natural materials, can be obtained.