The wine microbial ecosystem: Molecular interactions between yeast species and evidence for higher order interactions

Considering that global warming is changing berry ripening timing and progression, uncovering the molecular mechanisms and identifying key regulators governing berry ripening could provide important tools in maintaining high quality grapes and wine. NAC (NAM/ATAF/CUC) transcription factors represent an interesting family due to their key role in the developmental processes control, such as fruit-ripening-associated genes expression, and in the regulation of multiple stress responses. Between the 74 NAC family members, we selected 12 of them as putative regulators of berry ripening: NAC01, NAC03, NAC05, NAC11, NAC13, NAC17, NAC18, NAC26, NAC33, NAC37, NAC60 and NAC61.

The forchlorfenuron (CPPU) application is recommended in table-grape after fruit-set to boost berry sizing, albeit growers also apply CPPU during pre-flowering with controversial advantages. We examined the effect of single (BBCH 15) and double (BBCH 15 and 57) CPPU applications (2.25 mg/L a.s.) in a commercial vineyard. At each time, 75-100 bunches belonging to 6-9 vines were sprayed, and compared with unsprayed (CTRL). Leaf stomatal conductance (gs), cluster stem diameter and length were measured. At harvest, 25 berries/repetition were sampled for chemical composition, BSN incidence was counted (N° necrotic laterals/10 cm of stem) in 40 bunches/repetition. To test the role of air VPD on mineral composition, at BBCH 77, 50 CTRL clusters were bagged to induce a low VPD.

Ultra-premium champagne wines are characterized by a long stay on laths. The goal of the winemaker is to use all possible oenological techniques to keep the aromatic freshness of the future products. To that purpose, some champagne base wines can be aged on lees in oak barrels. However, if it is now acknowledged that such ageing practices contribute to the oxidative stability of dry white wines, no study has been done on Chardonnay champagne base wines designed for a long ageing on laths [1].

The mouthfeel of wine is one of the most important aspects of the organoleptic experience of tasting wine. In wine a great deal is known about certain compositional components and how they impact mouthfeel perception, such as phenolics. But there are other components where little is understood, such as oligosaccharides. Saccharides in general are found in very low concentrations with wine, especially compared to conventional foods. There is very little information about how oligosaccharides influence the mouthfeel perception of wine.

Cis-acting regulatory elements are DNA sequences that can be bound by transcription factors to regulate the expression of genes in a condition-dependent and tissue-specific way. It is nowadays possible to search for DNA motives and sequences that a given transcription factor is binding or at least can, but it is still hard to have a glance at all the transcription factors that are contemporaneously located at the same locus. Inspired by an existing technique that uses the CRISPR-Cas system in mammal cells, we are trying to develop a protocol to study such regulation in Vitis vinifera. Using the highly sequence-specific binding capacity of a catalytically inactive Cas9 protein (dCas9), our idea is to set up a system to target a desired sequence and precipitate all the crosslinked proteins and distantly interacting chromatin at this locus and analyze them.