Karine Pedneault,* Karine Delorme, Frédéric Pitre, and Paméla Nicolle
*Université du Québec en Outaouais, 78 rue Principale, Canada 
(karine.pedneault@uqo.ca)

Recent projections of increased temperatures linked to greenhouse gas emissions suggest an increased incidence of heat waves in Canada by 2100. In this context, vineyards will likely face more heat stress along with drier conditions, causing water deficit at critical periods of their development, including when new plots are established.

Interspecific hybrids varieties are issued from complex breeding programs involving Vitis vinifera and other Vitis species such as Vitis riparia and Vitis labrusca. In the context of global changes, interspecific hybrids bred for challenging environments such as cold climates are often expected to show greater resilience to stress than V. vinifera varieties. However, this assumption has been little studied. To fill this gap, we compared the metabolic response of young V. vinifera cv. Cabernet franc and Riesling and interspecific Vitis spp. Marquette and Vidal to heat stress, mild water stress, their combination, and a control under unstressed conditions over 21 days. Leaves were sampled, extracted, and analyzed by liquid chromatography-mass spectrometry-Orbitrap.

Over 200 metabolites were detected, including amino acids, phenolic compounds, and sugars. Depending on the variety, between 50 and 70 metabolites increased significantly in plants subjected to heat, water deficit, or combined stress treatments. Heat stress generated the strongest response, but combined stress provided mixed results among varieties. For instance, most metabolites upregulated by heat stress in Cabernet franc increased further when plants were exposed to combined stress. In Marquette and Vidal, most upregulated metabolites showed a lower response during combined stress. These results suggest that the stress mitigation mobilized fewer metabolic resources in Marquette and Vidal than in Cabernet franc, which could relate to a higher resilience in these varieties.

Funding Support: NSERC; AAFC; CGCN