Adapting plant material to face water stress in vineyards : which physiological targets for an optimal control of plant water status?

Aims: Water scarcity, associated with climate change, is a particular threat to the sustainability of viticulture in present areas of cultivation, usually prone to drought. Breeding grapevine for reduced water use, better water extraction and maintained production (i.e., high water use efficiency) is therefore of major interest. Methods and results: This requires a comprehensive knowledge of the physiological impacts of drought on yield and quality. Attention should be paid to those mechanisms involved in the regulation of water status in plant tissues, as it is the primary parameter affected by drought. Transpiration rate, which has a major influence on plant water status, should therefore receive special attention in breeding programs. Beyond scions, the role of rootstocks, which have been largely introduced in vineyards, should be investigated further as it determines water extraction capacity and could modify water balance in grafted plants. Conclusion: Here we review recent advances in the characterization of genetic variability in the control of water use and water status, whether induced by rootstock or scion. Significance and impact of the study: This review should help scientists in choosing the relevant physiological targets in their research on grapevine tolerance to drought, whether for breeding prospects or new management practices.