Inhibition of Mycelial Growth of Rhizoctonia Solani by Chitosan in vitro and in vivo

Objective: Evaluate the antifungal effect of chitosan againstRhizoctonia solani in vitroand the possible mechanisms of its induced activity in potato tubers to control black scurf disease. Methods: Thein vitroinfluence of chitosan at different concentrations on mycelial growth ofR. solaniwas tested by using the poisoned food technique in PDA medium. The effect of these concentrations on the development of lesion diameters in tubers inoculated withR. solanimycelium was assayed for 30 days. The concentration that showed the greatest inhibitory effect on lesion diameters was tested to assess the induced activity of defense-related enzymes in the infected tubers. Results: In the poisoned food technique, chitosan at 1% completely inhibited the growth ofR. solanimycelium.In vivotests showed that chitosan treatment at 0.5% effectively controlled the black scurf in tubers inoculated withR. solanimycelium. Chitosan increased the activities of defense-related enzymes such as Peroxidase (POD), Polyphenol Oxidase (PPO) and Phenylalanine Ammonia-lyase (PAL) in treated tubers of tested cultivars. Conclusion: This work demonstrated that chitosan directly inhibited the growth ofR. solani, and potentially elicited defense reaction in potato tubers.