Controlled-release nano-α-lipoic acid priming as a nanobiotechnological strategy to mitigate osmotic and oxidative stress in pea seedlings

Abiotic stresses such as drought and salinity are among the major environmental constraints limiting crop productivity, particularly in arid and semi-arid regions. These stresses induce osmotic imbalance, oxidative damage, and metabolic disruption, severely impairing plant growth and photosynthesis. The present study investigated the efficacy of nanochitosan-encapsulated α-lipoic acid as a novel seed priming agent to enhance drought and salinity tolerance in pea ( Pisum sativum L.) seedlings. Seven treatments were arranged in a completely randomized block design, including control non-primed (CNP), hydroprimed (CHP), salinity-stressed (NCS), drought-stressed (NCD), and nanochitosan-encapsulated α-lipoic acid-primed seedlings under normal (AlpP), saline (AlpPS), and drought (AlpPD) conditions. Results demonstrated that nano-ALA priming significantly improved plant height, biomass accumulation, and photosynthetic efficiency, accompanied by enhanced chlorophyll content, relative water content (RWC), and water-use efficiency (WUE) under both stress conditions. Primed seedlings exhibited markedly lower electrolyte leakage (EL), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA), reflecting reduced oxidative membrane injury. Furthermore, osmolyte accumulation (proline, soluble sugars, glycine betaine) and elevated non-enzymatic antioxidant levels (phenolics, ascorbate, glutathione, α-tocopherol) indicated improved osmotic regulation and redox homeostasis. Correlation analysis revealed strong positive associations between growth, water relations, and antioxidant metabolites, and negative correlations with oxidative stress markers. Nanoencapsulation of ALA in chitosan nanoparticles enhanced its stability, controlled release, and biological efficacy, enabling sustained protection against oxidative and osmotic stress. These findings establish nanochitosan-encapsulated α-lipoic acid priming as an innovative, safe, and sustainable nanobiotechnological approach for improving drought and salinity resilience in legume crops under climate-challenged conditions.