Molecular and physiological mechanisms of drought tolerance in grapevine.

Drought stress severely limits grapevine productivity and compromises fruit quality, with its adverse effects expected to intensify under ongoing climate change. This review synthesizes recent advances in elucidating the molecular and physiological mechanisms underlying drought tolerance in Vitis vinifera. Key physiological responses include abscisic acid (ABA)-mediated amplification of stomatal closure, osmotic adjustment, activation of antioxidant defense systems, and hydraulic vulnerability segmentation-a protective strategy involving the targeted sacrifice of petioles and basal leaves to maintain hydraulic integrity in stems and roots. These coordinated responses are regulated by a complex transcriptional network centered on NAC, WRKY, MYB, and bZIP transcription factors, and further modulated by hormone metabolism, potassium channel activity, aquaporin-facilitated water transport, and both enzymatic and non-enzymatic antioxidant pathways. We also identify critical knowledge gaps requiring urgent attention: (First) field-scale validation of transgenic or CRISPR-edited grapevine lines; (Second) the molecular basis of rootstock-scion signaling during drought stress; and (Third) the integration of multi-omics data with high-resolution phenotyping to accelerate precision breeding. Collectively, this review provides an integrative conceptual framework to support sustainable viticulture in water-limited environments.