Grapevine rootstocks for drought and heat tolerance: integrating physiological, hydraulic, and molecular mechanisms

Abstract

Abstract Among the numerous changes produced by global climate change, the increased frequency of heat waves and droughts is of great concern to viticulture. These changes are threatening the continuity of vineyards in certain regions and under the same crop management. This review has synthesised current knowledge on the physiological, molecular, and hydraulic mechanisms that confer varying levels of drought and heat tolerance in grapevine rootstocks. The widely known rootstocks 110R, 1103P, and 140Ru exhibit contrasting isohydric or anisohydric behaviours, which affect stomatal regulation, water-use efficiency, and hydraulic conductance. In recent decades, new rootstocks (M and RG) have been developed with the aim of combining drought and heat tolerance with agronomic advantages. Plants with greater tolerance to water stress have specific xylem anatomy and root morphology that permit them to maintain water uptake and status. Regarding xylem vessels, vessel diameter and density influence water uptake and cavitation vulnerability. These characteristics, as well as aquaporin activity and hormone levels (abscisic acid and 1-aminocyclopropane-1-carboxylic acid), are responsible for signalling stress responses and intermediating recovery. Heat stress also affects photosynthesis, phenology, and berry composition, also making oxidative damage. Plant active mechanisms such as the production of heat shock proteins and antioxidant systems for decreasing these effects. Actually, a problem when choosing the best rootstock-scion is that many studies describe individual processes, but few compare multiple rootstocks-scion under identical field conditions or evaluate combined drought and heat scenarios. Future research should shed light on in-depth questions regarding physiological, anatomical, and molecular mechanisms to identify genotypes with greater stress tolerance and inform breeding programmes. Selecting the appropriate rootstock and scion combination, along with vineyard management strategies, is key to maintaining grape production and wine quality in a warmer climate.