Exploring the regulatory role of the grapevine MIXTA homologue in cuticle formation and abiotic stress resilience

The quantity and distribution of polyphenols in musts play a fundamental role in the white winemaking. This is because these substances are exposed to oxidation reactions, which are catalysed by the polyphenol oxidase (PPO), leading to a decrease in the quality of the wines produced. PPO is inactivated by SO2, but currently, due to the restrictions of the legislation, other methodologies are being investigated. Ultra-High Pressure Homogenization (UHPH) is a non-thermal physic technology that exerts an ultrahigh pressure pumping (>200 MPa) of a fluid through a valve in a continuous system.

Crops are facing increasing biotic and abiotic stress pressures due to global changes. However, trade-off mechanisms between these stresses and the underlying physiological processes are still poorly understood, especially in perennial crop species. To better understand these trade-offs, we studied the effect of drought on grapevine (Vitis vinifera) physiology and esca-related wood fungal communities. Esca is a vascular disease caused by a community of wood-infecting pathogenic fungi, and characterized by trunk necrosis, leaf scorch symptoms, yield losses, and mortality.

La place prépondérante que prend le Massif Jurassien en Franche-Comté confère à la région un caractère montagneux qui a orienté l’agriculture vers l’élevage laitier. Cette vocation pastorale marquée et de rudes conditions climatiques sont à l’origine de la production, attestée depuis l’Antiquité, d’un fromage de réserve pour la longue période hivernale. Cette tradition fromagère, liée à des prairies naturelles, a perduré jusqu’à nos jours. La qualité et la spécificité du produit actuel, le fromage de Comté, ont été reconnues dès 1952 par l’attribution d’un label et dès 1958, par la reconnaissance d’un périmètre d’appellation d’origine contrôlée, l’A.O.C. Comté (fig. 1).

Dans le cadre d’une recherche sur les terroirs viticoles du canton de Vaud – Suisse, un modèle du microclimat intégrant température, relief, éclairement et pluviométrie a été conçu.

Chitosan is a polysaccharide produced from the deacetylation of chitin extracted from crustaceous and fungi. In winemaking chitosan is mainly used in the clarification of grape juice and wine, stabilization of white wines, removal of metals and to prevent wine spoilage by undesired microorganisms. The addition of chitosan to model wine systems was able to retard browning, reduce levels of metallic ions (Fe and Cu) and to protect varietal thiols due to its antiradical activity1. The present experiment was planned in order to evaluate the use of chitosan as a secondary antioxidant at three different stages of Sauvignon blanc fermentation and winemaking. Sauvignon blanc juices from three different locations were obtained at a commercial winery in Marlborough, New Zealand. One lots of grapes was collected from a receival bin and pressed into juice with a water-bag press, and a further juice sample was collected from a commercial pressing operation. Chitosan (1 g/L, low molecular weight, 75 – 85% deacetylated) was added to the juice after pressing, after cold settling, after fermentation, or at all these stages. Controls without any chitosan additions were also prepared.