Proline and Plant Stress Tolerance: Mechanisms, Applications, and Future Prospects

Abstract

Abiotic stress refers to the harmful impact of inorganic elements on biological organisms. Plants encounter several abiotic stresses daily during their life cycle, including extremes of temperature, salt, drought, nutrient inadequacy, and metal toxicity. They impact the growth of plants at the biological, physiological, and biochemical levels, resulting in a reduction of growth and a decrease in overall output. These factors impact approximately 90 per cent of the land used for agriculture, leading to a 50 per cent reduction in total yield. Proline, a proteinogenic amino acid, possesses a unique shape essential for plant metabolism. Proline plays a role in the primary metabolism of plants. Additionally, it is a prevalent compatible solute that accumulates in bacteria and plants when exposed to challenging environmental conditions. Higher plants exhibit an increase in proline concentration when exposed to different environmental challenges. Proline buildup has been seen in response to biotic stresses, intense light and UV radiation, heavy metals, oxidative stress, and drought conditions. The significance of proline in stress adjustment is often discussed due to its osmolyte characteristics and ability to mitigate water stress. Proline protective strategies include maintaining protein stability and antioxidant enzyme activity, directly scavenging reactive oxygen species (ROS), balancing intracellular redox homeostasis (such as the ratio of NADP+/NADPH and GSH/GSSG), and facilitating cellular communication through proline metabolism. This study aims to study the response of protein under several abiotic stresses and how proline metabolism helps in plant growth. When sprayed on leaves, proline enhances the growth of plants under stress.