Decoupling the effects of water and heat stress on Sauvignon blanc berries
Climate changes have important consequences in viticulture, heat waves accompanied by periods of drought are encountered more and more frequently. This study aims to evaluate the single and combined effect of water deficit and high temperatures on the thiol precursors biosynthesis in Sauvignon blanc grapes. For this purpose, a protocol has been developed for the cultivation of berries on a solid substrate. The berries, collected at three different times starting from veraison and grown in vitro, were subjected to 4 different treatments: control (C), water stress (WS), heat stress (HS), combined water and heat stress (WSHS). Water stress was simulated by adding abscisic acid to the culture medium, while different temperatures, respectively 25°C and 35°C, were managed with two illuminated climatic chambers. The expression of the main genes involved in the biosynthesis of thiol precursors, together with stress marker genes, was evaluated on the berries by qRT-PCR. Moreover, thiol precursors were analysed using an UHPLC/MS method. Results highlighted variable trends in the genes encoding GSTs (glutathione-S-transferase) and GGTs (γ-glutamyl-transferase), responsible for the synthesis of precursors. In detail, the VvGST3 gene was significantly down-regulated in thermal stresses, while HS and WSHS up-regulated the expression of VvGST2, VvGST5, VvGST25 and GGTs. Furthermore, the tested stress marker genes significantly confirm the success of both thermal and water stress conditions. The analysis of thiol precursors, showed that the concentration of Cys-3SH in the two last sampling dates well correlated with the expression of the above-mentioned genes. As opposite, a poor correlation was observed for Glut-3SH. Taken together these results allowed to identify a specific effect of heat and water stress on the regulation of the thiol precursors biosynthetic pathway in Sauvignon blanc berries during maturation.
Issue: ICGWS 2023
1Department of Life Sciences, University of Trieste, via Licio Giorgieri 10, 34127 Trieste, Italy
2Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, Via delle Scienze 206, 33100 Udine, Italy
3Kmetijski Istitut Slovenje (KIS), Hacquetova ulica 17, SI-1000 Ljubljana, Slovenia
Contact the author*
water stress, heat stress, climate change, berries culture