The regulatory roles of flavonoids, melatonin, and glycine betaine in plant salt stress response

Salt stress, one of the most detrimental environmental constraints, severely impairs plant growth and productivity by inducing ionic imbalance, osmotic stress, and oxidative damage. In response, plants synthesize a diverse array of secondary metabolites that help maintain cellular turgor, improve water uptake, restore osmotic homeostasis, scavenge reactive oxygen species, and fine-tune growth and development—collectively enhancing salt tolerance. Although considerable progress has been made in c