The effect of chitosan nanoparticles on immune responses in plants

Several strategies have been developed to control the diseases in plants however, the majority of them use chemical fungicides and pesticides. These agrochemicals have been in use for several decades to control various plant diseases. The widespread usage of agrochemicals has certainly decreased the outbreak of diseases, but at the same time has contributed to the development of resistance in pathogenic organisms. The emergence of resistant pathogens, the ever-increasing demand for crop productivity, and dwindling farmlands due to the explosion of the population have forced researchers to develop new, effective and inexpensive antimicrobial agrochemicals that are less likely to stimulate resistance in pathogenic organisms. The implications of chemical fungicides and pesticides in soil and water pollution have also mandated the search for alternative approaches to disease control management in plants. Chitosan, are deacetylated derivatives of chitin - a natural nontoxic polymer derived from the skeletal material of crustacean's shells and fungal cell walls. As nanotechnology has evolved as a promising field, the Chitosan-based nanoparticles have been considered one of the promising disease controlling agents and immune boosters in plants owing to their unique chemical and physical properties which increase the contact and permeability in cells. Its cationic nature, biodegradable, biocompatible, and antimicrobial properties make it a suitable candidate in the field of agriculture. Chitosan nanoparticles possess several agricultural applications including seedling growth and development, efficient nutrient usage, plant growth, antimicrobial activity, disease control, and elicitors of plant defense mechanisms. Chitosan nanoparticles have been evaluated as a potent inducer of antioxidant and defense enzymes in plants. Increased levels of defense responses due to the higher expression of defense-related genes have been recorded in transcriptome analysis of plants treated with chitosan nanoparticles. This present chapter documents the possible applications and mechanisms of chitosan nanoparticles to induce and augment immune responses in plants.