Chitosan strongly inhibited spore germination, germ tube elongation, and mycelial growth of B. cinerea and P. expansum in vitro, and damaged the plasma membranes
of spores of both pathogens. Chitosan treatment induced a significant increase in the activities of polyphenoloxidase (PPO), peroxidase (POD),
and enhanced the content of phenolic compounds in tomato fruit. These findings suggest that the effects of chitosan on gray mould and blue mould
in tomato fruit may be associated with the direct fungitoxic property against the pathogens, and the elicitation of biochemical defense responses
in fruit.