S20 - Session O2 - Moderately Increased Temperature during Berry Growth and Ripening Impacts Phenolic Compounds Accumulation in Vitis sp

Authors: Karine Pedneault *, Guillaume Sarrailhé, Mayank Pathak, Joana Pico Carbajo, Francisco Campos, Paméla Nicolle, Martine Dorais, Nicholas J.B. Brereton, Frédéric Pitre, Simone Castellarin

Global Warming significantly increases temperatures in northern countries such as Canada. However, its most significant impact is to extend the range of temperatures plants are exposed to during the growing season, and modify the growing-degree days accumulation patterns. As metabolic processes vary during berry development and ripening and are affected by temperature, we hypothesized that such variations may impact grapevine metabolism and composition of ripening berries. Thus, we triggered moderate temperature rises at different times during berry development of Vitis sp. L'Acadie blanc (Pre-veraison; post-veraison, whole season, and control), using mini-greenhouses installed on the rows, in a commercial vineyard (Nova Scotia, Canada). Plant physiology (photosynthesis, respiration) was followed. Berries were sampled at phenological stages EL-32, EL-36, EL-37 and EL-38 using liquid nitrogen and kept at n80ºC until analyses. Analyses included amino acids profile of berries and leaves by HPLC-RID-UV, and phenolic compounds from berries by LC-UV-MS/MS. Results : Grapevine growth under the mini-greenhouses showed increased photosynthesis and transpiration rate, mostly during the pre-veraison phase. Temperature treatment slightly affected the accumulation of amino acids in berries, with alanine being prominently accumulated in the Control when compared to the Whole season treatment. In contrast, all the treatments that benefited from a temperature rise, either early (Pre), late (Post) or during the whole season (Whole), showed higher levels of flavan-3-ols than the control, but the control and the Post treatments showed much higher levels of quercetin glucosides. Ripening also significantly affected the accumulation of amino acids and phenolic compounds in berries: for instance, the concentration in flavan-3-ols decreased significantly from stage EL-32 to stage EL-38 whereas the concentration in quercetin glycosides increased. This study provides insights about the relationships between temperature and the primary and secondary metabolism in grapevine and its significance to berry quality with regards to climate change.