Antifungal furanoterpenoids of sweet potato in relation to pathogenic and non-pathogenic fungi

Abstract

Sweet potato inoculated with Botryodiplodia theobromae, Botrytis cinerea or Cladosporium cucumerinum produced four antifungal compounds: ipomeamarone, ipomeamaronol and two unidentified compounds. The terpenoids were present at lower concentrations in spreading B. theobromae lesions than in the restricted lesions formed by the other two fungi. Tests on spore germination and sporeling growth showed that B. theobromae, the sweet potato pathogen, was less sensitive to the compounds at the concentrations at which they occurred in the tissue, whereas B. cinerea and C.cucumerinum were sensitive in varying degrees. In liquid culture, B. theobromae degraded all four compounds within 24 h, while the other fungi degraded them slowly or not at all.