Transition metals and light-dependent reactions: application of a response surface methodology approach

Climate change is leading to an increase in average temperature and in the frequency and severity of heatwaves that is already significantly affecting grapevine phenology and berry composition (Webb et al., 2010). This is compounded by water stress, which is well known to increase the vulnerability of grapevines and berries to heatwaves. In hot climate regions like australia, grape production is only possible due to relatively secure supplies of water for irrigation. However, the upper temperature limits for berry survival of well-watered grapevines remains to be tested.

Measurement of carbon isotope discrimination in berry juice sugars at maturity (δ13C) provides an integrated assessment of water use efficiency (WUE) during the period of berry ripening, and when collected over multiple seasons can be used as an indication of drought stress response. Berry juice δ13C measurements were carried out on 48 different varieties planted in a common garden experiment in Bordeaux, France from 2014 through 2021 and were paired with midday and predawn leaf water potential measurements on the same vines in a subset of six varieties. The aim was to discriminate a large panel of varieties based on their stomatal behaviour and potentially identify hydraulic traits characterizing drought tolerance by comparing δ13C and hydroscapes (the visualisation of plant stomatal behaviour as a response to predawn water potential). Cluster analysis found that δ13C values are likely affected by the differing phenology of each variety, resulting in berry ripening of different varieties taking place under different stress conditions within the same year. We accounted for these phenological differences and found that cluster analysis based on specific δ13C metrics created a classification of varieties that corresponds well to our current empirical understanding of their relative drought tolerances. In addition, we analysed the water potential regulation of the subset of six varieties (using the hydroscape approach) and found that it was well correlated with some δ13C metrics. Surprisingly, a variety’s water potential regulation (specifically its minimum critical leaf water potential under water deficit) was strongly correlated to δ13C values under well-watered conditions, suggesting that base WUE may have a stronger impact on drought tolerance than WUE under water deficit. These results give strong insights on the innate WUE of a very large panel of varieties and suggest that studies of drought tolerance should include traits expressed under non-limiting conditions.

Fluorescence spectroscopy combined with chemometrics has shown advantages in wine analysis due to being rapid, sensitive, and selective to fluorescent molecules. Especially due to the abundant phenolic compounds [1], the molecular fingerprints afforded by fluorescence spectroscopy can potentially be used to discern and track the change of wine composition, with two innovative investigations having been implemented.

The production of Port Wine requires the addition of grape spirit to stop the fermentation, ensuring the desired sweetness

Sulphites are by far the most widely used additive in the wine industry. In relation to health, the interaction of sulphites with the gut microbiota has not been addressed so far. Following the consumption of wine and other sulphite-containing foods, the gastrointestinal tract and the microbiome are one of the first barriers that these compounds face in the human organism. In this study, we used a previously validated gastrointestinal digestion model (SIMGI®) [1,2] to evaluate the effect of intestinal digestion of wine sulphites on the gut microbiome.