Grape berry ROS metabolism at different growth phases and in response to abiotic stress

Susceptibility of grape berries to stressors such as drought or heat changes according to the stress intensity and duration, but also depending on the berry developmental status at stress occurrence. For example, grapes in the herbaceous phase are more susceptible to drought stress than berries in the ripening stage. Drought and heat stress, which are predicted to increase in frequency and magnitude due to climate change, share a common effect in increasing the production of cytotoxic reactive oxygen species (ROS) in plant cells. While ROS are produced basally as signaling molecules, and plants have adapted mechanisms to detoxify them, stressful conditions increase their production. Given the economic importance of Vitis vinifera for the wine industry in Austria (and worldwide), it is important to understand how ROS metabolism interacts with other metabolic pathways active at the different stages of berry development, and therefore the effects of the timing of ROS-inducing stress factors. The inability to detoxify ROS may cause changes in berry metabolism and development that affect harvest quality, such as by increasing lipid oxidation, membrane damage, and subsequent cell death, the latter of which can cause symptoms such as berry shriveling in extreme cases. The project will explore the different strategies that grape berries could adopt to counteract an increase in ROS molecules produced in response to stressors, including the boost of the antioxidant pool (or de novo biosynthesis of antioxidant molecules) and the modification in the expression of ROS scavenging enzymes. The ROS scavenging capacity of developing grape tissue will be quantified by enzyme activity assays and gene expression analysis. Damage in berries caused by ROS will be quantified following drought and heat imposition in terms of the extent of lipid oxidation, cell death and changes in berry composition.