REVIEW: MOLECULAR AND PHYSIOLOGICAL REGULATION OF STOMATAL FUNCTION IN LEGUMES UNDER ABIOTIC STRESS: AN INTEGRATIVE OVERVIEW

• Current models of stomatal regulation are largely derived from non-legume species, and legume specific molecular regulation remains scarce. • Comparative analysis reveals both conserved mechanisms and legume-specific regulatory features of stomatal regulation. • Genome duplications contributed to diversification of stomatal regulatory elements in legume species. • ROS are key modulators of stomatal function in legumes. Climate change and population growth are exerting strong pressure on agriculture, reinforcing the need for climate-resilient crops. Stomata, microscopic pores on the leaf epidermis that regulate gas exchange and transpiration represent a key target for improving water use efficiency and stress tolerance. However, much of the current understanding of stomatal regulation derives from Arabidopsis thaliana and other non-crop models, highlighting the need to evaluate how these regulatory frameworks apply to agronomically important species such as legumes, where significant knowledge gaps remain. In this review, we synthesize current advances in the molecular and physiological regulation of stomatal function and development in legumes, with particular emphasis on abiotic stress responses. We integrate evidence on hormone signaling pathways, especially abscisic acid, cytokinins, brassinosteroids, and ethylene, together with transcription factor (TF) families such as MYB, bHLH, NAC, and WRKY, and the central role of reactive oxygen species (ROS) as signaling intermediates. We highlight both conserved regulatory modules and lineage specific diversification potentially associated with genome duplication events characteristic of legume evolution. By comparing regulatory mechanisms described in legumes with those established in model species, we identify major knowledge gaps and propose promising genetic targets for optimizing stomatal dynamics and enhancing stress resilience in legume crops. This integrative overview provides a framework for future functional studies and for the identification of molecular targets relevant to breeding climate resilient legume cultivars.