Grape composition is strongly influenced by climate growing conditions and their modifications, as expected in the coming years (increased temperature, elevated atmospheric CO2 levels and water scarcity), may significantly modify the biochemical composition of berries at harvest, and thus wine typicity. The rich intra-varietal diversity opens the possibility to select better adapted plant material in order to mitigate the potential negative effects of climate change on grape quality. The effects of increased temperature, elevated atmospheric CO2 levels and water deficit on grape composition of 'Tempranillo' clones with different length of their reproductive cycle were studied with the aim of detecting potential interesting traits among them. Fruit-bearing cuttings were grown in temperature gradient greenhouses and in growth chamber greenhouses under two temperatures (ambient temperature versus ambient temperature +4°C), two CO2 levels (400 versus 700 ppm) and two water regimes (well-watered versus water deficit), both in combination or independently, in order to simulate future climate change scenarios. The concentration of sugars, organic acids and anthocyanins in grapes was measured. Elevated temperature hastened sugar accumulation in grapes, both acting individually and in combination with high CO2. However, this effect was mitigated by water deficit. On the other hand, elevated temperature increased malic acid degradation, notably when combined with elevated CO2 level and water deficit. Total anthocyanin levels at maturity were not strongly modified by the increase of temperature and CO2 levels but the combination of elevated temperature, high CO2 and water deficit led to a strong decrease of anthocyanin levels. The magnitude of these alterations was different among clones indicating intra-varietal variability in the response of 'Tempranillo' to climate conditions. These results highlight the importance of multi-stress approaches to provide realistic insights into the response of clones to optimize the adaptation of traditional cultivars in their growing regions.

We thank MINECO, AGL2014-56075-C2-1-R; Fundación Universitaria de Navarra, PIUNA 2018, and Asociación de Amigos de la Universidad de Navarra for the financial support. Special thanks to M. Oyarzun, A. Urdiain, H. Santesteban and C. Renaud for their technical assistance and E. García-Escudero, J.M. Martínez-Zapater, E. Baroja (ICVV), J.F. Cibrain (EVENA) and R. García (Vitis Navarra) for the selection of clones and for providing plant material.

Trabajo presentado en el XI International Symposium on Grapevine Physiology and Biotechnology, celebrado en Stellenbosch (Sudáfrica), del 31 de octubre al 5 de noviembre de 2021

Peer reviewed