Chilean Scientist Claudio Pastenes Explores Abscisic Acid’s Role in Combating Climate Change in Vineyards
The impact of climate change on modern viticulture is a growing concern, as rising temperatures and water scarcity directly affect vine productivity and grape quality. Chilean scientist Claudio Pastenes, an agronomist and PhD in Molecular Biology and Biotechnology from the University of Chile, addressed these challenges at the Enoforum event held recently in Chile. In his presentation titled “Climate Change in the Vineyard and Drought: Opportunities and Challenges,” he highlighted the role of abscisic acid, a natural hormone in grapevines, in helping the plants adapt to water stress conditions.
Pastenes explained that climate change leads to significant physiological changes in vines, accelerating secondary metabolism processes that are crucial for the production of compounds like anthocyanins and other phenolics, which are essential for wine quality. Abscisic acid, a key hormone, increases in concentration during veraison, a stage when grapes change color and begin to ripen. This increase in abscisic acid induces the synthesis of anthocyanins, pigments that not only determine the color of red grapes and wines but also contribute to the stability of this color over time.
He noted that anthocyanin accumulation is regulated by specific genes such as PAL (phenylalanine ammonia-lyase) and ANS (anthocyanidin synthase), which are involved in various stages of the phenolic pathway. According to recent studies, exogenous application of abscisic acid during veraison prolongs the activity of these genes, extending anthocyanin synthesis beyond the usual 30-day period. This leads to higher pigment accumulation in the grapes, which can directly impact the wine’s color intensity and stability.
Pastenes also addressed the competition between anthocyanin synthesis and that of other compounds like flavonols and tannins, which are also derived from the same metabolic pathway. Typically, their production decreases after veraison, but the application of abscisic acid can delay this decline, maintaining higher levels of flavonols and tannins for a longer period. This suggests a complex interaction between these metabolic routes. Flavonols and condensed tannins are critical for wine structure, contributing to characteristics like astringency, bitterness, and aging potential. Additionally, they act as copigments, stabilizing anthocyanins and enhancing color persistence in wine over time.
Experimental data presented by Pastenes showed that 40 days after abscisic acid application, there was a significant increase in flavonol and tannin concentrations, indicating a possible positive feedback mechanism in the regulation of these pathways. He explained that abscisic acid serves as a signal that enables the vine to adapt to drought conditions by regulating stomatal closure and the accumulation of secondary metabolites. This reduces water loss and optimizes vine performance under high temperatures and low water availability. Furthermore, the increase in anthocyanins and modulation of tannins could enhance certain sensory aspects of wine, such as color stability and texture.
Pastenes concluded by emphasizing that, despite the challenges posed by climate change, there is an opportunity to adjust viticultural and enological practices using tools like abscisic acid application to mitigate the negative effects of water stress and improve wine quality in increasingly extreme climatic contexts.