Functional characterisation of genetic elements regulating bunch morphology in grapevine

Volatile organic compounds (VOCs) are emitted by nearly all plant organs of the plants, including leaves. They play a key role in the communication with other organisms, therefore they are involved in plant defence against phytopathogens. In this study VOCs from grapevine leaves of two varieties of Vitis vinifera infected by Erysiphe necator were analysed. The varieties were selected based on their susceptibility to pathogen, Kishmish Vatkana has the Ren1 resistance gene and Zamarrica showed high susceptibility in previous trials.

During alcoholic fermentation, nitrogen is an essential nutrient for yeast as it plays a key role in sugar transport and biosynthesis of wine aromatic compounds (thiols, esters, higher alcohols). The main issue of a lack in yeast assimilable nitrogen (yan) in winemaking is sluggish or stuck fermentations promoting the growth of alteration species which may lead to economic losses. However, correcting this nitrogen deficiency is sometimes not enough to restore proper fermentation performance. This suggests the existence of other nutritional shortages.

Le concept AOC permet, par une délimitation précise, la mise en valeur de terroirs particulièrement adaptés à la viticulture. Seuls les terroirs ainsi identifiés peuvent produire des vins portant le nom de l’AOC. Le nom de cette AOC ne peut être utilisé que pour des vins issus de terroirs compris dans l’aire d’appellation, sous peine de sanctions pénales. La délimitation ainsi opérée participe à la protection du nom de l’AOC. A l’inverse, le terroir délimité n’est pas protégé.

Nebbiolo (Vitis vinifera L.) is one of the most important wine red cultivar of North-west Italy. A better understanding of the complex relations among grape aromatic and phenolic maturity and environmental factors may strongly contribute to the improvement of the quality of Nebbiolo wines.

Grape harvest time is one of the most fundamental aspects that affect grape quality and thus wine quality. Many factors influence the decision of harvest; among them technological and phenolic maturity of grape. Technological ripeness is mainly related to sugar concentration, titratable acidity and pH. Conventional methods for chemical analysis of grapes are normally sample-destructive, time-consuming, include laborious sample preparation steps, and generate chemical waste, thereby limiting their utility in online/in-line quality monitoring. Moreover, destructive analyses can be performed only on a limited number of fruit pieces and, thus, their statistical relevance could be limited. This study evaluated the ability of a lab-scale hyperspectral imaging (HYP-IM) technique to predict titratable acidity, organic acid and sugar content of grapes. Samples of Cabernet franc and Chenin blanc grapes were consecutively collected six times at weekly intervals after veraison. The images were recorded thanks to the hyperspectral imaging camera Pica L (Resonon) in a spectral range from 400 to 1000 nm. Statistics were performed using Microsoft Xlstat software. Successively, the berries were analyzed for their sugar (glucose and fructose) and organic acid (malic and tartaric acid) content and titratable acidity according to usual methods.