Stomatal Mechanisms Underlying Drought Tolerance in Rice (Oryza Sativa L.): Integrating Physiological, Molecular Regulation, and Breeding Strategies

Drought reduces rice (Oryza sativa L.) productivity by impairing leaf water status, activating abscisic acid (ABA)-mediated stomatal closure, and disrupting carbon-water trade-offs.Rice adapts to drought through rapid stomatal signaling, developmental modifications, and whole-plant integration of hydraulic regulation, mesophyll conductance, and canopy architecture.Growing evidence indicates that moderate reductions in stomatal density (SD) can enhance water-use efficiency (WUE) and drought tolerance with minimal yield penalties when coordinated with non-stomatal traits.However, extreme reductions in SD may restrict carbon assimilation and impair thermoregulation.Recent studies have identified SD-related quantitative trait loci (QTLs) and candidate genes, alongside successful genome editing of EPF/EPFL family members, providing valuable targets for droughtresilient rice breeding.Rice deploys morphological, physiological, and molecular strategies to maximize WUE while sustaining photosynthesis under drought, including SD and aperture modulation, ABA and reactive oxygen species (ROS)-mediated signaling, and transcriptional regulation of droughtresponsive genes and transcription factors.Despite these advances, key challenges remain in integrating stomatal traits with whole-plant hydraulics, root architecture, reproductive resilience, and genotype-by-environment interactions under field conditions.Future breeding strategies should combine physiological phenotyping with genomics, genome editing, and digital agriculture tools to develop climate-resilient rice cultivars capable of sustaining productivity under drought.