Thirty-five Years of Research on Deoxynivalenol, a Trichothecene Mycotoxin: with Special Reference to Its Discovery and Co-occurrence with Nivalenol in Japan

Abstract

Deoxynivalenol (DON), a trichothecene mycotoxin, was characterized together with nivalenol (NIV) from naturally infected wheat and barley grains of the 1970 epidemic in Kagawa ** , Japan. DON, 3-acetyl-DON (3-ADON) and 3,15-di-acetyl-DON (3,15-DADON) were identified as metabolites of Fusarium roseum No.117 (=F. graminearum ATCC 28114), a toxic isolate from the cereals of the 1970 epidemic, and their toxicological properties in animals, including acute toxicity, emetic activity, and in vivo de-epoxydation metabolism into DOM-1 (deepoxy-DON), were elucidated. Natural co-occurrence of DON and NIV in the domestic cereals was found to be common not only in southern Japan but also in other regions, and the geographic difference in the occurrence of both toxins in Japan was elucidated. In terms of myco-toxigenicity, F. graminearum strains isolated from crop fields were divided into two types: DON-and NIV-producers, and DON-producer was further subdivided into two subtypes, 3-ADON-and 15-acetyl-DON-producers by biotransfor-mation experiment of 3,15-DADON as a precursor. The geographic differences in the incidence of these producers in Japan were observed. Correlation between the incidence of the toxin producers and the occurrence of DON and NIV were investigated by field trials. For screening NIV alone or in combination with DON in cereals, specific monoclonal antibodies were produced, and practical ELISA kits were successfully developed. In relation to our previous findings, current advances in the molecular phylogenetic analysis of mycotoxigenic F. graminearum, the molecular genetics of trichothecene biosynthesis, among others, were briefly reviewed.