MYCOTOXIN PRODUCING POTENTIAL OF FUSARIUM-GRAMINEARUM ISOLATES FROM URUGUAYAN BARLEY

Twelve isolates of Fusarium graminearum were obtained from barley grai ns collected from different Uruguayan regions (harvest 1993-94). This was the predominant fungal species contaminating the crop due to a par ticular humid and warm season with cold nights conducive to toxin prod uction The isolates were grown on moist, sterile rice, extracted with aqueous methanol, and examined for mycotoxin production. Zearalenone ( ZEA) and the trichothecenes deoxynivalenol (DON), 3- and 15-acetyl-DON (AcDON), nivalenol (NIV), fusarenon-X (FX) and T-2 toxin (T-2) were a nalyzed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) and confirmed by gas chromatography-mass spectr ometry (GC-MS). Eleven of the 12 strains were DON and/or ZEA producers and 9 were AcDON positive. No NIV, or FX were detected. One strain pr oduced T-2. The predominant acetyl-DON isomer was 15-AcDON. Mass-spect ral analysis yielded detectable levels of other mycotoxins, 13-OH-apot richothecenes, 11-epiapotrichothecenes, culmorin, sambucinol, and isot richodermol being the most numerous. From the metabolic profiles it is suggested that Uruguayan F. graminearum strains belong to the chemoty pe IB (DON/15-AcDON). The predominance of this chemotype is in accorda nce with data from Canada, United States, Mexico and Argentina which h ave similar climatic conditions that would favor F. graminearum growth and mycotoxin production.