The effects of heat and drought on ROS metabolism and its consequences on grape berries at different stages of development

Berries of Vitis vinifera undergo many changes in their biochemistry and metabolism throughout development. Grape berries go from being photosynthetically active and largely dependent on xylem water uptake, to being heterotrophic and completely dependent on phloem transport after veraison (the switch to the ripening stage). Hence, the timing of abiotic stress such a drought and heat can have contrasting effects on metabolic processes that affect final yield as well as harvest and wine quality. Drought and heat stress are known to lead to the production of reactive oxygen species (ROS), whose roles range from important signalling molecules to cytotoxic substances capable of damaging cellular structures. My PhD project focuses on the relationship between drought stress, heat stress, and the effects of ensuing ROS production on berry metabolism, focussing more specifically on cell membrane lipids. Experiments will focus on alterations to membrane lipids such as carbon chain length, saturation and peroxidation. Data from lipidomic analyses will be analysed in light of measurements of secondary metabolites in berries and vitality of berry mesocarp cells following stress application, as well as how drought and heat stress at different developmental stages of berries affect the activity of ROS scavenging enzymes, and whether or not this exacerbates the cytotoxic effects of ROS.