Plants respond to water stress through complex physiological and biochemical mechanisms to adapt to environmental conditions. Water stress negatively affects photosynthesis and plant growth, leading to reduced productivity. Plants have evolved molecular and physiological mechanisms to enhance water-use efficiency and drought tolerance. This review summarizes the molecular mechanisms involved in plant responses to water stress, including stomatal signaling, ion transport, and the role of transcription factors in regulating stress tolerance and growth adjustment. Stomatal closure is a critical response to water stress, mediated by abscisic acid (ABA) signaling. ABA is produced during drought and triggers a cascade of physiological responses, including stomatal closure. ABA transport systems, such as ABCG25 and ABCG40, play a key role in the movement of ABA from vascular tissues to guard cells, enabling stomatal responses. The activation of anion channels and K+ channels in guard cells leads to stomatal closure, reducing water loss. Transcription factors, such as MYB, DREB/CBF, ABF/AREB, NAC, and WRKY, regulate the expression of genes involved in drought responses. These factors are involved in the regulation of stomatal aperture and plant drought tolerance. Additionally, the expression of genes involved in photosynthesis and reactive oxygen species (ROS) scavenging is crucial for maintaining plant productivity under water stress. Water stress also affects photosynthesis by reducing CO2 availability and increasing ROS production. Plants have evolved mechanisms to protect photosynthesis, including the up-regulation of genes involved in ROS scavenging and the regulation of chloroplast function through retrograde signaling. These mechanisms help plants adapt to water stress and maintain growth. Understanding the molecular mechanisms of plant responses to water stress is essential for improving plant stress tolerance through biotechnology. Advances in genome editing technologies, such as CRISPR/Cas, offer new opportunities to modify key genes involved in stress tolerance while maintaining productivity. Future research should focus on identifying gene variants associated with significant agronomic traits to enhance plant resilience to environmental stresses.Plants respond to water stress through complex physiological and biochemical mechanisms to adapt to environmental conditions. Water stress negatively affects photosynthesis and plant growth, leading to reduced productivity. Plants have evolved molecular and physiological mechanisms to enhance water-use efficiency and drought tolerance. This review summarizes the molecular mechanisms involved in plant responses to water stress, including stomatal signaling, ion transport, and the role of transcription factors in regulating stress tolerance and growth adjustment. Stomatal closure is a critical response to water stress, mediated by abscisic acid (ABA) signaling. ABA is produced during drought and triggers a cascade of physiological responses, including stomatal closure. ABA transport systems, such as ABCG25 and ABCG40, play a key role in the movement of ABA from vascular tissues to guard cells, enabling stomatal responses. The activation of anion channels and K+ channels in guard cells leads to stomatal closure, reducing water loss. Transcription factors, such as MYB, DREB/CBF, ABF/AREB, NAC, and WRKY, regulate the expression of genes involved in drought responses. These factors are involved in the regulation of stomatal aperture and plant drought tolerance. Additionally, the expression of genes involved in photosynthesis and reactive oxygen species (ROS) scavenging is crucial for maintaining plant productivity under water stress. Water stress also affects photosynthesis by reducing CO2 availability and increasing ROS production. Plants have evolved mechanisms to protect photosynthesis, including the up-regulation of genes involved in ROS scavenging and the regulation of chloroplast function through retrograde signaling. These mechanisms help plants adapt to water stress and maintain growth. Understanding the molecular mechanisms of plant responses to water stress is essential for improving plant stress tolerance through biotechnology. Advances in genome editing technologies, such as CRISPR/Cas, offer new opportunities to modify key genes involved in stress tolerance while maintaining productivity. Future research should focus on identifying gene variants associated with significant agronomic traits to enhance plant resilience to environmental stresses.