TOXIGENICITY OF FUSARIUM SPECIES AND SUBSPECIES IN SECTION GIBBOSUM FROM DIFFERENT REGIONS OF AUSTRALIA

The toxicity of cultures of Fusarium species and subspecies in section Gibbosum from soils from locations in various climatic regions of Aus tralia was determined using a chick bioassay. Most cultures of F. comp actum and F. acuminatum subsp. armeniacum were found to be highly toxi c irrespective of geographical origin. The other species and subspecie s in section Gibbosum viz; F. acuminatum subsp. acuminatum, F. equiset i, F. scirpi, and F. longipes, were shown to be non-toxic or of low to xicity. Selected culture extracts of F. compactum, F. acuminatum armen iacum and F. acuminatum acuminatum were analysed by gas chromatography after clean up and hydrolysis for the four main trichothecene familie s, namely; nivalenol (NIV), deoxynivalenol (DON), scirpentriol (Sctol) and T-2 tetraol (T-2tol). Some cultures of F. compactum were found to produce high levels of T-2tol derivatives while others produced high levels of Sctol derivatives. Cultures of F. acuminatum armeniacum prod uced high levels of T-2tol derivatives and trace levels of Sctol deriv atives. In contrast, only trace levels of T-2tol and Sctol were detect ed in hydrolysed culture extracts of F. acuminatum acuminatum. GC/MS a nalysis of individual trichothecene derivatives in culture extracts of F. compactum indicated that the main trichothecenes produced were eit her acuminatin or diacetoxyscirpenol respectively, while F. acuminatum armeniacum was found to produce mainly T-2 toxin and neosolaniol.