Chitosan nanoparticles for sustainable agriculture: interactions with leaf surface and protective effect on dsRNA as functionalizing agent

Climate change and population growth are causing significant issues in the agricultural world, among which the worsening of environmental stresses suffered by crops and the inefficient use of resources must be highlighted. That’s why it’s necessary to find eco-sustainable solutions that can guarantee adequate production efficiency without affecting environmental health. Among the most advanced technologies, the development of nanomaterials partially replacing the conventional treatments with synthetic pesticides and fertilizers, stands out, given their more efficient transport of bioactive substances to plants and protection from damaging factors. Considering organic materials, nano-chitosan is even eco-compatible and obtainable through circular economy. Another innovation concerning the defense of crops is the exploitation of the so-called RNA-interference mechanism. Specific dsRNAs targeting an essential gene of a pathogen or weed can be applied exogenously, triggering a pathway that leads to gene silencing into the organism. A major issue, however, consists in the easy degradability of these sequences if applied naked, which makes the technology still unlikely for agricultural up-scaling. In this regard, the aim of our research was to verify the feasibility of dsRNA application on plants by means of functionalized chitosan nanoparticles (NPs), thus allowing its efficient delivery and protection. After defining the best synthesis protocol of NPs, these were used for different tests. To verify their ability to adhere to the leaf surface, they were observed by confocal microscope on two plant species thanks to a fluorescent probe. Subsequently, after their functionalization with nucleotides, their protective capacity was studied. These tests proved to be fundamental for the prosecution of the work concerning the evaluation of the formulation efficacy on plant pathogens.