Roles of the Mediator complex and transcriptional activators/repressors in regulating plant gene expression under salt stress

Abiotic stresses, including drought, salinity, and extreme temperatures, pose significant threats to global agriculture by adversely affecting plant growth, productivity, and the sustainability of arable land. These challenges are intensifying due to accelerated climate change and rapid population growth, which together necessitate increased agricultural output despite declining land availability. Among these stresses, salinity is particularly detrimental, as it induces osmotic and ionic imbalances, disrupts nutrient homeostasis, and triggers excessive production of reactive oxygen species (ROS), ultimately leading to oxidative damage and impairment of key physiological processes. To mitigate such stresses, plants activate complex genetic and molecular defense mechanisms, including transcriptional reprogramming mediated by transcription factors (TFs). Emerging research highlights the pivotal role of the plant Mediator complex a conserved, multisubunit transcriptional coactivator in coordinating responses to environmental cues. The Mediator complex functions as a central integrator of transcriptional regulation by facilitating interactions between TFs and RNA polymerase II. In both model and crop species, such as Arabidopsis thaliana , Oryza sativa , and Glycine max , mediator subunits exhibit tissue-specific and developmentally regulated expression patterns, thereby influencing critical biological processes including flowering, root architecture, and abiotic stress responses. The objective of this review is to provide a comprehensive overview of the structural organization, functional roles, and regulatory mechanisms of plant mediator complex subunits in response to salinity stress. By synthesizing recent advances in plant molecular biology, this review aims to elucidate the potential of mediator-based transcriptional regulation as a promising target for the development of stress-resilient crops. • Salinity stress disrupts plant growth by causing osmotic, ionic, and oxidative imbalances. • Plants employ transcriptional reprogramming and Mediator complex activity to combat salinity stress. • The Mediator complex acts as a key regulator linking transcription factors to RNA polymerase II for stress resilience.