Unraveling the Genetic and Physiological Mechanisms of Salt Tolerance Mediated by Phytohormones in Rice (Oryza sativa L.): A Review

Soil salinity threatens global rice productivity, thereby exacerbating food security challenges in arid and semi-arid regions. Most previous reviews have examined individual phytohormones in isolation or focused on descriptive gene lists without providing integrated mechanistic frameworks. This review offers an updated synthesis organized around three integrative perspectives. These include: (1) a tripartite framework showing how phytohormones coordinately regulate osmotic, ionic, and oxidative stress pathways; (2) a hormonal crosstalk model that explains the profound context dependence of phytohormone efficacy and why single-phytohormone applications show variable field success; and (3) a translational roadmap connecting molecular insights to practical applications through CRISPR-based engineering of crosstalk networks and nano-formulation delivery systems. Phytohormones such as abscisic acid (ABA), gibberellins (GAs), salicylic acid (SA), auxins (IAA), and cytokinins (CKs) enhance osmotic adjustment (via OsP5CS ), restore ionic homeostasis (via OsSOS1 and OsHKT1;5 ), and reinforce antioxidant defenses (via OsAPX and OsCAT ). However, their effectiveness is governed by hormonal crosstalk. Key interactions, including ABA–GA antagonism (growth versus defense) and SA-mediated redox priming, help explain context-dependent outcomes in the field. This review also evaluates current delivery strategies (seed priming and foliar spraying) and discusses emerging approaches that merit further investigation, such as nano - formulations and CRISPR-based modification of crosstalk nodes (e.g., OsNAC74 and OsCKX2 ). Although conceptually promising, their field applicability, regulatory pathways, and economic viability remain to be systematically validated.