Effects of carbon sources and amines on induction of trichothecene production byFusarium asiaticumin liquid culture

Abstract

Fusarium asiaticum infects cereal crops and produces trichothecenes such as deoxynivalenol and nivalenol. To determine the trichothecene induction mechanism, effects of carbon sources on the production of deoxynivalenol, nivalenol, 3-acetyl deoxynivalenol (3ADON), and 4-acetyl nivalenol (4ANIV) were examined in liquid cultures incubated with various strains. Sucrose supported significantly higher levels of acetylated trichothecene production in all strains than did the other carbon sources. Structural isomers of sucrose did not induce trichothecene production. The inducing effect of sucrose on trichothecene production was lost after the carbon source in the culture medium changed from sucrose to maltose in the process of incubation. Tri4 and Tri5 expressions were specifically up-regulated in the sucrose-containing medium and down-regulated with sucrose exhaustion. These findings suggest that F. asiaticum recognizes sucrose molecules and regulates Tri gene expression and trichothecene production. Moreover, an accelerating effect on trichothecene production by acidification of the culture medium containing specific amines during fungal incubation was exhibited only in the presence of sucrose in the medium. F. asiaticum induces trichothecene production in the presence of sucrose and accelerates the production when the medium containing specific amines is acidified during incubation.