Stage-resolved coordination of ion homeostasis, proton transport, and redox regulation supports saline-alkaline tolerance and yield stability in rice

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ABSTRACT Saline-alkaline stress imposes combined ionic and high-pH constraints, yet its integrated effects across developmental stages in rice remain poorly understood. This study evaluated a gamma-induced mutant line (SAT-9) derived from the salt-sensitive cultivar Pathum Thani 1 (PTT1) in comparison with Pokkali under controlled hydroponic conditions with defined salinity and saline-alkaline treatments. Responses were assessed at both seedling and booting stages, including ion homeostasis, physiological performance, oxidative status, gene expression, and yield-related traits. SAT-9 maintained low Na + accumulation and stable Na + /K + ratios across tissues, indicating effective ion homeostasis under stress. This was associated with coordinated upregulation of key transporters ( OsHKT1;5 , OsSOS1 ) and proton pump activity ( OsAHA7 ), supporting maintenance of electrochemical gradients under elevated pH. In parallel, enhanced antioxidant capacity in SAT-9 limited H 2 O 2 and malondialdehyde accumulation, preserving membrane integrity and photosynthetic efficiency. These responses were sustained at the booting stage, where SAT-9 maintained stable growth, reduced spikelet sterility, and minimal changes in grain yield and quality under saline-alkaline conditions. In contrast, PTT1 showed excessive Na + accumulation, disrupted ionic balance, and severe oxidative damage, while Pokkali exhibited partial tolerance that declined under high pH. This study suggests that saline-alkaline tolerance is governed by the integration of ion transport, proton-coupled regulation, and redox homeostasis across developmental stages. This study provides an integrative, stage-resolved framework linking ion homeostasis, proton transport, and redox regulation to yield stability under saline-alkaline stress. The results highlight the potential of mutation-derived germplasm for developing rice adapted to saline-alkaline environments.

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Related topics: Plant Stress Responses and Tolerance · Plant Micronutrient Interactions and Effects · Plant responses to water stress