Melatonin-mediated phytohormonal crosstalk improves salt stress tolerance in plants.

Main conclusion: Salinity adversely affects plant growth and productivity. Melatonin plays a central role in various signaling pathways and shows extensive crosstalk with other phytohormones. Melatonin-phytohormone crosstalk strategies have emerged as promising tools to enhance crop resilience under salinity stress. The insights presented here provide a foundation for the development of salt-tolerant horticultural cultivars through melatonin-centered biotechnological and breeding approaches. Salinity stress is a major abiotic factor limiting plant growth and crop productivity worldwide, increasingly heightened by climate change and unsustainable irrigation practices. Melatonin, a pleiotropic molecule originally discovered in animals, has recently emerged as a key regulator in plant stress responses, particularly through its interaction with other phytohormonal signaling networks. Although recent studies support melatonin's protective functions in salt stress tolerance, the precise molecular mechanisms underlying some of these interactions remain largely unresolved. This review synthesizes current advances in understanding the role of melatonin in enhancing salt stress tolerance in horticultural plants. Particularly, melatonin's crosstalk with other phytohormones, including abscisic acid and auxins, forms a coordinated complex adaptive responses during salt stress. This review highlights key knowledge gaps and proposes future research directions, mainly in the direction of applying melatonin-mediated signaling to engineer salt-tolerant cultivars. Thus, this review provides a comprehensive resource for advancing our understanding of melatonin's integrative role in plant hormonal networks and its potential applications in sustainable horticulture under salinity stress.