“Terroir” studies in the Côtes du Rhône controlled appellation: from zoning to application

Studies on wineomics (wine’s metabolome) have increased considerably over the last two decades. Wine results from many environmental, human and biological factors leading to a specific metabolome for each terroir. NMR metabolomics is a particularly effective tool for studying the metabolome since it allows the rapid and simultaneous detection of major compounds from several chemical families.1 Quantitative NMR has already proven its effectiveness in monitoring the authenticity of still wines.

Root system architecture (RSA) is important for soil exploration and edaphic resources acquisition by the plant, and thus contributes largely to its productivity and adaptation to environmental stresses, particularly soil water deficit. In grafted grapevine, while the degree of drought tolerance induced by the rootstock has been well documented in the vineyard, information about the underlying physiological processes, particularly at the root level, is scarce, due to the inherent difficulties in observing large root systems in situ. The objectives of this study were to determine genetic differences in the root architectural traits and their relationships to water uptake in two Vitis rootstocks genotypes (RGM, 140Ru) differing in their adaptation to drought. Young rootstocks grafted upon the Riesling variety were transplanted into cylindrical tubes and in 2D rhizotrons under two conditions, well watered and moderate water stress. Root traits were analyzed by digital imaging and the amount of transpired water was measured gravimetrically twice a week. Root phenotyping after 30 days reveal substantial variation in RSA traits between genotypes despite similar total root mass; the drought-tolerant 140Ru showed higher root length density in the deep layer, while the drought-sensitive RGM was characterised by shallow-angled root system development with more basal roots and a larger proportion of fine roots in the upper half of the tube. Water deficit affected canopy size and shoot mass to a greater extent than root development and architectural-related traits for both 140Ru and RGM, suggesting vertical distribution of roots was controlled by genotype rather than plasticity to soil water regime. The deeper root system of 140Ru as compared to RGM correlated with greater daily water uptake and sustained stomata opening under water-limited conditions but had little effect on above-ground growth. Our results highlight that grapevine rootstocks have constitutively distinct RSA phenotypes and that, in the context of climate change, those that develop an extensive root network at depth may provide a desirable advantage to the plant in coping with reduced water resources.

Yeast cells possess a cell wall comprising primarily glycoproteins, mannans, and glucan polymers. Several yeast phenotypes relevant for fermentation, wine processing, and wine quality are correlated with cell wall properties. To investigate the effect of wine fermentation on cell wall composition, a study was performed using mid-infrared (MIR) spectroscopy coupled with multivariate methods (i.e., PCA and OPLS-DA). A total of 40 yeast strains were evaluated, including Saccharomyces strains (laboratory and industrial) and non-Saccharomyces species. Cells were fermented in both synthetic MS300 and Chardonnay grape must to stationery phase, processed, and scanned in the MIR spectrum.

To our knowledge all the studies about laccase kinetics and its inhibition have been performed with substrates and conditions very different from those of real grape juice. Moreover, none of these researches really measure enzymatic browning, since they have not taken into account what happens after the oxidation of o-diphenols in o-diquinones and their subsequent polymerization to form melanins1. For that reason, the aim of this research was to develop a new model to measure the kinetics of browning caused by Botrytis cinerea laccase under conditions much closer to those of grape juice and using the substrates naturally present in it.

The Champagne vineyard extends over 35,300 ha under the Appellation d’Origine Contrôlée, of which 30,000 are in production. It mainly covers 3 departments: in order of importance, Marne (68% of the appellation area), Aube (22%) and Aisne (10%), and more anecdotally Haute Marne and Seine and Mame. It is a young vineyard (for more than half of the surface, the winegrowers have the experience of only one generation of vines), and fragmented (more than half of the exploitations extend over less than 1 ha; the average size of a cadastral parcel is 12 ares).