Response to powdery and downy mildew of varieties with disease resistance genes (PIWI)

Aroma compounds are critical for wine sensory quality, yet their concentration and expression can be altered during winemaking and aging by sorption onto solid surfaces such as oak wood, yeast lees, or yeast derivatives (1-3).

Although vitamins stand as major actors to yeasts prime metabolic pathways, their significance in oenology and winemaking remains rather obscure nowadays, having been mostly unexplored for several decades.

Following anecdotal evidence of unwanted ‘tropical’ character in red wines resulting from vineyard interventions and a subsequent yeast trial observing higher ‘red fruit’ character correlated with higher thiol concentrations, the role of polyfunctional thiols in commercial Australian red wines was investigated.
First, trials into the known tropical thiol modulation technique of foliar applications of sulfur and urea were conducted in parallel on Chardonnay and Shiraz.1 The Chardonnay wines showed expected results with elevated concentrations of 3-sulfanylhexanol (3-SH) and 3-sulfanylhexyl acetate (3-SHA), whereas the Shiraz wines lacked 3-SHA. Furthermore, the Shiraz wines were described as ‘drain’ (known as ‘reductive’ aroma character) during sensory evaluation although they did not contain thiols traditionally associated with ‘reductive’ thiols (H2S, methanethiol etc.).

Œnococcus oeni is a wine-associated lactic acid bacterium performs the malolactic fermentation, which improves the taste and aromatic complexity of many wine.

Grapevine leafroll associated virus 2 (GLRaV-2) is one of the most common damaging viral diseases in vines, causing significant reductions in photosynthesis, yield and grape quality. In this study, we tested the hypothesis that the leaf net photosynthesis and the transport of sugars to the berries is progressively reduced along the season in vines infected with GLRaV-2, and consequently, the yield (kg per plant) and total soluble solids (TSS) at the berry harvest-ripe stage are lower than non-infected vines.