Comparative Multi-Omics Profiling of Drought-Tolerant and Drought-Sensitive Grapevine Cultivars Identifies VvGRIK1 as a Conserved Drought-Responsive Regulator Associated with Redox and Bioenergetic Homeostasis

Drought stress severely limits grapevine (Vitis spp.) productivity, yet the regulatory mechanisms distinguishing drought-tolerant and drought-sensitive cultivars remain insufficiently understood. In this study, we integrated transcriptomic, metabolomic, physiological, and functional analyses to compare drought responses between the tolerant cultivar ‘Miguang’ and the sensitive cultivar ‘Red Globe’, together with previously generated datasets from ‘Shine Muscat’ and ‘Thompson Seedless’. Compared with sensitive cultivars, tolerant cultivars showed stronger antioxidant capacity, lower lipid peroxidation, and more coordinated changes in pathways related to redox balance, osmotic adjustment, and energy metabolism. In ‘Miguang’, drought responses were associated with activation of the pentose phosphate pathway, accumulation of tricarboxylic acid cycle intermediates, and genotype-specific alternative splicing events affecting metabolic and signaling genes. Comparative analysis across four cultivars identified VvGRIK1 as a conserved drought-responsive regulator associated with redox and bioenergetic homeostasis. Heterologous overexpression of VvGRIK1 in tobacco enhanced drought-related physiological performance by increasing antioxidant enzyme activities and reducing membrane damage. Yeast two-hybrid assays and molecular docking further suggested a potential interaction between VvGRIK1 and VvKING1, a SnRK1-related energy sensor. Together, these findings suggest that the VvGRIK1-SnRK1 module may contribute to drought adaptation by coordinating redox protection and energy homeostasis, providing a candidate regulatory target for future functional studies and grapevine molecular breeding.