Book excerpt: Role of Chitosan and Chitosan-Based Nanomaterials in Plant Sciences explores the physiological, morphological, biochemical and molecular regulation of chitosan and chitosan-based nanoparticles in plants in normal conditions, as well as during different stresses, and their probable mechanism of operation in the tolerance mechanism. The book stimulates further research in the field of chitosan and will foster further interests for researchers, academicians and scientists worldwide. Nanotechnology is being used widely in all disciplines of science and technology, including plant sciences. Chitosan has widely been reported as a beneficial organic compound for the growth and developments of plants and it plays a protective role for the plants against abiotic and biotic stresses. Yet there are very few books available that deal exclusively with Chitosan and Chitosan based nanoparticles impacts on plants respectively. Analyzes the research on chitosan and chitosan-based nanomaterials in plant sciences Includes the latest information on toxicity and human exposure Reviews modifications and alterations in plant expressions and biochemical pathways