Photosynthesis is a critical process affected by water deficits, primarily through reduced CO2 diffusion to chloroplasts and metabolic constraints. The impact of these limitations varies with the intensity of stress, the presence of superimposed stresses, and the species involved. Leaf carbohydrate status, altered directly or indirectly by water deficits, acts as a metabolic signal, but its role is not fully understood. Other key signals include abscisic acid (ABA), which regulates stomatal aperture and gene expression related to stress response, and other hormones that act concurrently or antagonistically. Redox control of the energy balance in photosynthetic cells also plays a significant role. A meta-analysis of over 450 papers published in the last 15 years reveals the complex network of interactions and regulations of photosynthesis in plants under water deficits. However, the results are often fragmented and non-comparable, making it challenging to relate molecular events to plant physiological status and stress intensity. The study highlights the importance of genes ABI1 and ABI3, which show similar responses to water scarcity in Arabidopsis and barley, regardless of the stress type and intensity. These genes are associated with ABA-mediated metabolic responses and stomatal aperture regulation. The analysis also emphasizes the need for more systematic and comprehensive studies to better understand the metabolic connections between drought, photosynthesis, and plant responses.Photosynthesis is a critical process affected by water deficits, primarily through reduced CO2 diffusion to chloroplasts and metabolic constraints. The impact of these limitations varies with the intensity of stress, the presence of superimposed stresses, and the species involved. Leaf carbohydrate status, altered directly or indirectly by water deficits, acts as a metabolic signal, but its role is not fully understood. Other key signals include abscisic acid (ABA), which regulates stomatal aperture and gene expression related to stress response, and other hormones that act concurrently or antagonistically. Redox control of the energy balance in photosynthetic cells also plays a significant role. A meta-analysis of over 450 papers published in the last 15 years reveals the complex network of interactions and regulations of photosynthesis in plants under water deficits. However, the results are often fragmented and non-comparable, making it challenging to relate molecular events to plant physiological status and stress intensity. The study highlights the importance of genes ABI1 and ABI3, which show similar responses to water scarcity in Arabidopsis and barley, regardless of the stress type and intensity. These genes are associated with ABA-mediated metabolic responses and stomatal aperture regulation. The analysis also emphasizes the need for more systematic and comprehensive studies to better understand the metabolic connections between drought, photosynthesis, and plant responses.