An antifungal dispersion system was prepared by oleoyl-chitosan (O-chitosan) nanoparticles, and the
antifungal activity against several plant pathogenic fungi was investigated. Under scanning electron
microscopy,thenanoparticles formulationappeared to beuniformwithalmost spherical shape. Theparticle
size of nanoparticles was around 296.962 nm. Transmission electron microscopy observation showed
that nanoparticles could be well distributed in potato dextrose agar medium. Mycelium growth experiment
demonstrated that Nigrospora sphaerica, Botryosphaeria dothidea, Nigrospora oryzae and Alternaria
tenuissima were chitosan-sensitive, whileGibberella zeae and Fusarium culmorum were chitosan-resistant.
The antifungal index was increased as the concentration of nanoparticles increased for chitosan-sensitive
fungi. Fatty acid analyses revealed that plasma membranes of chitosan-sensitive fungi were shown to
have lower levels of unsaturated fatty acid than chitosan-resistant fungi. Phylogenetic analysis based
on ITS gene sequences indicated that two chitosan-resistant fungi had a near phylogenetic relationship.
Results showed that O-chitosan nanoparticles could be a useful alternative for controlling pathogenic
fungi in agriculture