Towards the definition of a detailed transcriptomic map of grape berry development

Malolactic fermentation (MLF) is a secondary step in the vinification process and it follows alcoholic fermentation (AF) which is predominantly carried out by Saccharomyces cerevisiae. These two processes result in the degradation of metabolites to produce secondary metabolites which also contribute to the final wine flavour and quality. AF results in the production of ethanol and carbon dioxide from sugars and MLF stems from the degradation of L-malic acid (a dicarboxylic acid) to L-lactic acid (a monocarboxylic acid). The latter process results in a smoother texture as the acidity of the wine is reduced by the process, it also adds to the flavour complexity of the wine.

In 2004, at its general assembly, the oiv adopted the transfer of its scientific and technical heritage from the office to the international organisation of vine and wine. Unesco defines heritage as “our legacy from the past, what we live with today, and what we pass on to future generations.”

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Goriška Brda est la région viticole située le plus à l’ouest de la Slovénie, attenante au Collio d’Italie. Goriška Brda (2020 ha de vignobles) a une longue tradition d’élevage viticole. La proximité de la mer Adriatique (Golfe de Trieste) au sud-ouest et des Alpes Juliennes au nord contribue à un climat caractéristique et unique qui influe sur la croissance et la fertilité de la vigne. La constitution des sols, un climat typique et un relief mouvementé provoquent des différences dans la production du raisin, sa quantité et sa qualité. L’utilisation du zonage ou du microzonage permettraient d’atténuer les influences des facteurs climatiques et du sol sur la production de la vigne ou d’en profiter. Pour évaluer la signification des différents facteurs, nous avons résumé et réuni les modèles de différents auteurs.

Stomatal traits determine grapevine water use, carbon supply, and water stress, which directly impact yield and berry chemistry. Breeding for stomatal traits has the strong potential to improve grapevine performance under future, drier conditions, but the trait values that breeders should target are unknown. We used a functional-structural plant model developed for grapevine (HydroShoot) to determine how stomatal traits impact canopy gas exchange, water potential, and temperature under historical and future conditions in high-quality and hot-climate California wine regions (Napa and the Central Valley). Historical climate (1990-2010) was collected from weather stations and future climate (2079-99) was projected from 4 representative climate models for California, assuming medium- and high-emissions (RCP 4.5 and 8.5). Five trait parameterizations, representing mean and extreme values for the maximum stomatal conductance (gmax) and leaf water potential threshold for stomatal closure (Ψsc), were defined from meta-analyses. Compared to mean trait values, the water-spending extremes (highest gmax or most negative Ysc) had negligible benefits for carbon gain and canopy cooling, but exacerbated vine water use and stress, for both sites and climate scenarios. These traits increased cumulative transpiration by 8 – 17%, changed cumulative carbon gain by -4 – 3%, and reduced minimum water potentials by 10 – 18%. Conversely, the water-saving extremes (lowest gmax or least negative Ψsc) strongly reduced water use and stress, but potentially compromised the carbon supply for ripening. Under RCP 8.5 conditions, these traits reduced transpiration by 22 – 35% and carbon gain by 9 – 16% and increased minimum water potentials by 20 – 28%, compared to mean values. Overall, selecting for more water-saving stomatal traits could improve water-use efficiency and avoid the detrimental effects of highly negative canopy water potentials on yield and quality, but more work is needed to evaluate whether these benefits outweigh the consequences of minor declines in carbon gain for fruit production.