Diversity of leaf functioning under water deficit in a large grapevine panel: high throughput phenotyping and genetic analyses

In the Cognac region in France, Ugni blanc is the most planted grape variety (98% of the 80 500 ha). This vine region is in expansion due to the success of the associated well-known brandy and the need of high grape yield to guarrantee the production of base wine for distillation. About 2 to 3000 ha are newly planted each year and rootstocks are one powerfull tool for vineyard adaptation to soil or climate change. As rootstocks ensure water and mineral nutrient supplies to the scion, it is important to better understand their effect on berry compostionnal parameters such as sugars and nitrogen compounds, which are the main precursors for fermentary aroma metabolites, the latter being quality markers for Cognac after distillation.

UNESCO World Heritage as the link, Europe as the area covered. VITOUR network is born on this idea, on Loire Valley Mission and InterLoire’s initiative. It gathers vineyards inscribed on UNESCO World Heritage List.

In recent years, numerous studies have been carried out at the OIV on oenological tannins, both with regard to oenological properties and methods of characterization. The results of these recent studies have led to the revision of the general monograph and the drafting of four new monographs, one for each of the four chemical classes into which the tannins have been grouped: ellagitannins, gallotannins, procyanidins/prodelphinidins, profisetinidins/prorobinetinins.

The Grenache Noir grape variety, due to its originality and its representativeness, contributes very directly to the quality and typicality of the wines of the Rhône Valley. It is generally appreciated for its varied aromatic palette and for the roundness and suppleness it gives to wines. Since 1995, the Rhodanien Institute has set up a network of reference plots representative of the different types of terroir present in the southern zone of the Côtes du Rhône Appellation (TRUC, 1997; VAUDOUR et al, 1996 ) . Publications on the aromatic composition of grapes and wines are very abundant, but only a few articles have appeared on the Grenache grape variety PAUMES et al., 1986).

Nitrogen (N) nutrition of the vineyard strongly influences the must and the wine compositions. Several chemical markers present in wine (i.e., proline, succinic acid, higher alcohols and phenolic compounds) have been proposed for the cultivar Chasselas, as indicators of N deficiency in the grape must at harvest [1]. Grape genetics potentially influences the impact of N deficiency on grape composition, as well as on the concentration of potential indicators in the wine. The goal of this study was to evaluate if the che- mical markers found in Chasselas wine can be extended for other white wines to indicate N deficiency in the grape must.