Effect of Capsaicin on Germination of Colletotrichum capsici Conidia

Abstract

                Different varieties of cultivated chilies (Capsicum spp.) produce different amounts of capsaicin, but the biological role of this compound has not yet been elucidated. High concentrations of capsaicin in some chili varieties are possibly associated with resistance to anthracnose, a fruit rot disease. Consequently, this paper examines the role of capsaicin in preventing conidial germination of the anthracnose-causing fungus Colletotrichum capsici. Conidia were germinated on potato dextrose agar media supplemented with 40% methanol/aqueous capsaicin solution in final concentrations of 0, 25, 50, 100 and 200 mg/l. Each plate was inoculated with a solution containing approximately 400 conidia of C. capsici, then incubated at 25°C and 70% relative humidity under continuous light for 5, 6 and 7 hours.

                Approximately 96% of conidia germinated on the capsaicin-free medium after six hours of incubation, but only 53% germinated on PDA containing 25 mg/l capsaicin. Subsequently, conidia germination increased to 91% after 7 hours on plates containing 25 mg/l capsaicin. Germination of C. capsici conidia was completely inhibited on the PDA with 100 and 200 mg/l of capsaicin.