A vine physiology-based terroir study in the AOC-Lavaux region in Switzerland

Climate change and harvest date decisions have led to the evolution of must quality over the last decades. Increases in must sugar concentrations are among the most obvious consequences, quantitatively. Saccharomyces cerevisiae is a robust and acid tolerant organism. These properties, its sugar to ethanol conversion rate and ethanol tolerance make it the ideal production organism for wine fermentations. Unfortunately, high sugar concentrations may affect S. cerevisiae and lead to growth inhibition or yeast lysis, and cause sluggish or stuck fermentations. Even sublethal conditions cause a hyperosmotic stress response in S. cerevisiae which leads to increased formation of fermentation by-products, including acetic acid, which may exceed legal limits in some wines.

Yeast cell walls (CWs) may adsorb wine components with a significant impact on wine quality. When dealing with red wines, this adsorption is mainly related to physicochemical interactions between wine polyphenols and cell wall mannoproteins. However, mannoproteins are a heterogeneous family of complex peptidoglycans including long and highly branched N-linked oligosaccharides and short linear O-linked oligosaccharides, resulting in a huge structural diversity.

French lawmakers have chosen the family-type winegrowing business as the benchmark for drafting the legal framework for winegrowing businesses and winegrowers. In france (source: msa), in 2022, there were 1,444 new winegrowers, an increase of 3% compared with 2021, representing 10% of new farm managers. The retention rate for winegrowers is 75% (up 13% on 2021), compared with 77% for all agricultural sectors (stable).

Over the past 70 years, scientific literature has consistently illustrated the advantageous effects of arbuscular mycorrhiza fungi (AMF) on plant growth and stress tolerance. Recent reviews not only reaffirm these findings but also underscore the pivotal role of AMF in ensuring the sustainability of viticulture. In fact, various companies actively promote commercial inoculants based on AMF as biofertilizers or biostimulants for sustainable viticulture. However, despite the touted benefits of these products, the consistent effectiveness of AMF inoculants in real-world field conditions remains uncertain.

Botrytis cinerea Pers., the causal agent of grey mould disease, is responsible for substantial economic losses, as it causes reduction of grape and wine quality and quantity. Exploitation of antagonistic yeasts is a promising strategy for controlling grey mould incidence and limiting the usage of synthetic fungicides. In our previous studies, 119 different indigenous yeasts were screened for putative multidimensional modes of action against filamentous fungus B. cinerea [1]. The most promissing biocontrol yeast was Pichia guilliermondii ZIM624, which exhibited several anatagonistic traits (production of cell wall degrading enzymes, chitinase and β-1,3-glucanase; demonstration of in vitro inhibitory effect on B. cinerea mycelia radial growth; production of antifungal volatiles, assimilation of a broad diversity of carbon sources, contributing to its competitivnes in inhabiting grapes in nature).