Modern approaches to enhancing abiotic stress tolerance using phytoprotectants: A focus on encapsulated proline

Abstract

Abiotic stress conditions such as salinity, water deficit, heat, cold, and heavy metal toxicity severely affect plant growth and productivity. To cope with these adverse environmental conditions, the exogenous application of phytoprotectants has emerged as a promising strategy to enhance plant tolerance. Phytoprotectants such as proline, putrescine, ascorbic acid, and phytomelatonin improve physiological and biochemical responses by interacting with phytohormonal signaling pathways to strengthen stress adaptation mechanisms. Among them, proline is particularly notable for its multifunctional role as an osmolyte, antioxidant, signaling molecule, and stabilizer of cellular structures. Exogenous proline application under stress conditions has been shown to improve growth parameters, activate antioxidant defense systems, reduce oxidative stress, and upregulate stress-responsive genes. However, excessive accumulation of these compounds can produce metabolic imbalances, which highlights the need for precise management. Recent advances in encapsulation technologies provide a novel approach to improve the stability, bioavailability, and controlled release of phytoprotectants. This review offers a comprehensive overview of the roles and interactions of key phytoprotectants, with a special focus on proline, and explores how encapsulation strategies can enhance their effectiveness in mitigating abiotic stress in plants.