Trichothecene and zearalenone production, in culture, by isolates of Fusarium pseudograminearum from western Canada

One hundred and twenty-seven isolates of Fusarium pseudograminearum were obtained from seeds and vegetativeparts of cereals and other gramineae grown in western Canada. Culture of the isolates on agar selective for Fusarium graminearum allowed a successful differentiation from E graminearum. Sterilized rice (40% moisture content) was inoculated with a single germinated spore of isolates identified as E pseudograminearum and was incubated at 23 degrees C. After 14 days of incubation, mycelium was taken from each culture, and the DNA was extracted to detect the tri5 gene by polymerase chain reaction analysis and confirm the species identity. After 21 days of incubation, mycotoxins were quantified in dried rice. All isolates contained the tri5 gene. Deoxynivalenol (DON) was produced in 125 of the 127 isolates, 3-acetyldeoxynivatenol (3-ADON) in 122 isolates, 15-acetyideoxynivalenol (15-ADON) in 2 isolates, diacetoxyscirpenol (DAS) in 17 isolates, and zearalenone in 100 isolates; both nivalenol (NIV) and fusarenon X (FX) were detected in I isolate. There appears to be three chemotypes: DON-3-ADON, DON-15-ADON, and NIV. Neither of the two 15-ADON producers or the NIV producer formed DAS. This is the first time that the production of DAS and FX is associated with E pseudograminearum. None of the isolates produced HT-2 toxin or T-2 toxin at detectable levels.