The exploitation of Croatian grapevine genetic resources for the breeding of new resistant cultivars 

It is common to find tanks in the winery with wine below their capacity due to wine transfers between tanks of different capacities or the interruption of operations for periods of a few days. This situation implies the existence of an ullage space in the tank with prolonged contact with the wine causing its absorption/oxidation. Oxygen uptake from the air headspace over the wine due to differences in the partial pressure of O2 can be rapid, up to 1.5 mL of O2 per liter of wine in one hour and 100 cm2 of surface area1 and up to saturation after 4 hours.

Vine growth circumstances are becoming warmer and drier because of climate change. Higher temperatures advance ripening to a point in the season less conducive to the production of fine wine, while drought reduces yields (Van Leeuwen et al., 2019). Several wine-producing regions around the world have already recognized threats to their viticultural viability (Santos et al., 2020). An economical and cost-effective strategy for adaptation is the employment of late-ripening, drought-resistant plant material (varieties, clones, and rootstocks).

Glutathione plays a key role in preventing some oxidative processes during winemaking. This molecule limits the must enzymatic oxidation, reacts with caffeic acid and generates a colourless compound that prevents subsequent browning. It also has a protective effect on wine aroma, preventing the oxidation of the volatile compounds with a high sensory impact.

Secondary (or specialised) metabolites such as terpenes and phenolic compounds are produced by plants for various roles which include defence against pathogens and herbivores, protection against abiotic stress, and plant signalling. Additionally, these metabolites influence grapevine quality traits such as colour, aroma, taste, and nutritional value. However, the biosynthesis of these metabolites is often complex and controlled by multiple genes which in grapevine are predominantly uncharacterised.

Global warming and increased frequency and/or severity of drought events are among the most threatening consequences of climate change for agricultural crops. In response to drought, grapevine (as many other plants) exhibits osmotic adjustment through active accumulation of osmolytes which in turn shift the leaf turgor loss point (TLP) to more negative values, allowing to maintain stomata opened at lower water potentials1. We investigated the capacity of Pinot noir leaves to modulate their osmotic potential as a function of: (i) time (seasonal osmoregulation), (ii) growing temperatures, and (iii) drought events, to enhance comprehension of the resilience of grapevines in drought conditions. We performed trails under semi-controlled field conditions, and in two different greenhouse chambers (20/15 °C vs 25/20 °C day/night). For two consecutive vegetative seasons, grafted potted grapevines (Pinot noir/SO4) were subjected to two different water regimes for at least 30 days: well-watered (WW) and water deficit (WD).