Effects of chitosan on plant tolerance to salt stress

Abstract

Salt stress seriously affects plant growth and development. Salt stress occurs mainly due to increased Na+ and Cl- concentrations in the soil. Water absorption from the roots brings these ions to the plant, causing ion toxicity and loss of homeostasis. Salt stress leads to osmotic, ionic, and oxidative stress in plants. Anti-stress mechanisms are activated through ROS, NO, and hormone signalling pathways. Chitosan is a non-toxic biological polymer, easily degradable and highly biocompatible. The applications of chitosan in agriculture are essential because chitosan can activate plant defence systems against biotic and abiotic stress. Many studies have demonstrated the presence of chitin receptors on plant cell membranes, which are the starting point of signalling pathways, stimulating defence responses against stress. Chitosan maintains plant growth under salt stress, protects the photosynthetic apparatus, increases the synthesis of osmolytes, activates antioxidant enzymes, and stimulates stomatal closure to reduce the absorption of Na+ and Cl- from roots. The impact of chitosan on the defence response of plants depends on the molecular size, deacetylation, and concentration of chitosan and depends on the genetic characteristics of the plants.