Molecular mechanisms and regulatory networks of salt stress tolerance in plants.

Soil salinity is a major threat to crop productivity, sustainable agriculture, and global food security, with more than 833 million hectares of land affected worldwide. Salt stress restricts plant growth through osmotic stress, ion toxicity, oxidative damage, membrane disruption, reduced photosynthesis, and yield loss. Plants respond through coordinated regulatory networks that connect early stress perception with ion balance, osmotic adjustment, hormone signaling, transcript regulation, and protein modification. Recent advances have identified several sensory and signaling modules involved in salinity responses, including calcium signaling, receptor like kinases, FERONIA, OSCA, MOCA, annexins, and mechanosensitive channels that detect ionic, osmotic, and mechanical changes. Established pathways such as the SOS pathway and GABA shunt are included as established background mechanisms for sodium homeostasis and metabolic adjustment under saline conditions. Hormonal networks involving abscisic acid, ethylene, jasmonic acid, auxin, gibberellins, and brassinosteroids coordinate root architecture, stomatal control, antioxidant defense, growth restraint, and post-stress recovery. Emerging regulatory layers mediated by microRNAs, phosphorylation, ubiquitination, and SUMOylation further fine tune transcript stability, protein activity, ion transport, redox balance, and stress resilience. A central challenge is the translational gap between model species and crops, since many mechanisms defined in Arabidopsis and rice still lack functional validation in major crop species and halophytes. Integrating conserved and species dependent mechanisms with crop centered validation will help convert molecular knowledge into breeding, genome editing, and management strategies for saline agriculture.