Role of brassinolide in enhancing plant tolerance to salinity stress

Salinity stress is a major constraint to global agriculture, reducing crop yields, degrading arable land and causing economic losses. In many regions, it is intensified by factors such as seawater intrusion, poor irrigation practices and climate-related changes in water availability. While mild salinity may not severely hinder growth, high salinity disrupts ion homeostasis, induces oxidative stress and impairs physiological processes including water and nutrient transport, leading to stunted growth and reduced biomass. Brassinolide (BL), a naturally occurring plant steroid hormone, plays a pivotal role in mitigating salinity stress by regulating ion balance, enhancing antioxidant defense systems, modulating stress-responsive gene expression (e.g., ion transporters, antioxidant enzymes) and promoting growth and development. Its exogenous application through foliar sprays, seed priming or soil treatments has shown promise in improving salt tolerance. This review outlines the mechanisms of salinity stress in plants and highlights the role of BL in alleviating its effects, with emphasis on signalling pathways, ion homeostasis, regulation of Na/H antiporters and reactive oxygen species (ROS) scavenging.