The potential of rootstock and scion interactions to regulate grapevine responses to the environment

Recent studies predict that viticulture may be endangered in some traditional wine growing areas because of ongoing and future changes in climate. Increasing temperatures may reduce the suitability of currently grown cultivars because of changes in phenology and fruit composition. Water scarcity and limited access to freshwater for irrigation may also affect both yield and fruit quality. In many regions, the maintenance of wine production will rely on modifications of cultural practices to adapt grapevines to new climatic conditions. As the vast majority of vineyards worldwide are grown grafted, rootstocks are a key component of the adaptive potential of these agrosystems. Although there are methodological difficulties in analysing root systems in situ and scion × rootstock interactions in a woody perennial crop like grapevine, there is an increasing scientific interest in advancing our understanding of how rootstocks communicate with scions (and vice versa), and modulate grapevine functioning. Since 20 years, we have been studying scion/rootstock interactions in grapevine at the agronomical, physiological, molecular and (epi)genetic levels, with the view to determine the underlying mechanisms. This work has shown that interactions between rootstock and scion genotypes are considerable and that they are difficult to predict from individual partner performances. Mobilizing genome-based approaches combined with advanced phenotyping studies should improve our understanding of this complex issue. Our overall objective is to provide knowledge for breeding new rootstocks and helping growers to choose the best genotype combinations to adapt their vineyard to limiting environments. This paper provides an overview of the most recent outputs of this research.