Metabolic responses of the grape (Vitis vinifera L.) berry to environmental stimuli

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Predicted annual trends in temperature and precipitation linked to climate change are expected to affect grape production in wine regions worldwide. However, in Canada, these changes may favour the potential expansion of the wine industry in future years. Considerable variability in seasonal temperatures and precipitation extremes are also anticipated to occur, highlighting the critical need to understand how grape metabolism and composition respond to extreme environmental stimuli. The long-term objective of my research program is to investigate the molecular and physiological mechanisms that regulate ripening and composition of wine-grapes in response to environmental factors and climates. This will help winegrowers to develop sustainable adaptation strategies to produce premium grapes in current and future climates. This program's short-term objectives are: 1) To understand the role of sugar and hormones in regulating terpenes - powerful odorants that affect the wine quality - in grapes. We will compare terpene levels with sugar and hormone levels during grape ripening and in cell cultures exposed to different sugar and hormone treatments. The study of genomes and transcriptomes will identify the genes involved in the regulation of terpene biosynthesis in the grapes of major terpene-producing varieties and how terpene genes respond to the different sugar and hormone treatments. 2) To determine the effect of climate and, in particular, of environmental factors such as light and temperature on terpene biosynthesis in grapes. First, we will assess the extent to which sunlight, temperature, water availability, and subsequently their interactions affect the terpene biosynthesis. Then we will assess the variability of terpene levels in Canadian vineyards and model how these metabolites accumulate in the vineyard of several wine regions in relation to changes in climate. The hormones and genes that are involved in the relay of these stimuli on the terpene pathways will be identified by comparing the hormone and transcript profiles with the terpene levels. 3) To assess the response of grape growth and composition to water deficit in varieties with contrasting stomatal behaviors. This will determine the extent to which the innate stomatal sensitivity to water deficit of different grapevine varieties affects grape berry growth and metabolism. This study will consider commercial varieties that span a range of stomatal behaviors and assess how the grape growth and metabolism (sugars, acids, hormones, phenolics, volatile organic compounds such as terpenes) respond to water deficit. This research program will help advance the science of grape biology and ultimately the wine industry, and is positioned to train HQP in the areas of viticulture/horticulture, with the aim of recruiting HQP from underrepresented groups, who will contribute back to the expanding Canadian grape and wine industry.