Abstract
The immunomodulatory role of the natural biopolymer, chitosan, has already been demonstrated in plants, whilst its nanoparticles have only been examined for biomedical applications. In our present study, we have investigated the possible ability and mechanism of chitosan nanoparticles (CNP) to induce and augment immune responses in plants. CNP-treatment of leaves produced significant improvement in the plant’s innate immune response through induction of defense enzyme activity, upregulation of defense related genes including that of several antioxidant enzymes as well as elevation of the levels of total phenolics. It is also possible that the extracellular localization of CNP may also play a role in the observed upregulation of defense response in plants. Nitric oxide (NO), an important signaling molecule in plant defense, was also observed to increase following CNP treatment. However, such CNP-mediated immuno-stimulation was significantly mitigated when NO production was inhibited, indicating a possible role of NO in such immune induction. Taken together, our results suggest that CNP may be used as a more effective phytosanitary or disease control agent compared to natural chitosan for sustainable organic cultivation.
Highlights
The immunomodulatory role of the natural biopolymer, chitosan, has already been demonstrated in plants, whilst its nanoparticles have only been examined for biomedical applications
Particle size obtained from such Transmission Electron Microscopy (TEM) analysis is seemingly more accurate than the size measured by the dynamic light scattering method (DLS)
This is because, in TEM analysis particles are measured in their dry state, whereas in DLS, the nanoparticles being in their hydrated state project an apparently larger hydrodynamic diameter due to the presence of solvent layers[6]
Summary
The immunomodulatory role of the natural biopolymer, chitosan, has already been demonstrated in plants, whilst its nanoparticles have only been examined for biomedical applications. The growing interest and demand for organic or non-polluted food/crop from the more health conscious consumers and the challenge posed by the evolving adaptability of phyto-pathogens due to uncontrolled use of synthetic chemicals, have led to the exploration of alternative crop protection strategies in recent times The search for such alternative disease management strategies supported by the advancement of nanotechnology, have paved for application studies of nanomaterials as a potential candidate for disease control in plants. Chitosan has been reported to induce multifaceted disease resistance[3] This natural biopolymer is known for its unique properties like, biodegradability, nontoxicity and antimicrobial activity, popularizing its use as an elicitor molecule for different host-pathogen interaction studies[2]. Our results convincingly establish CNP as a potential biocompatible plant defense tool for better control of plant diseases in the future
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