Determination of Deoxynivalenol and Nivalenol Chemotypes of Fusarium graminearum Isolates from China by PCR Assay

Fusarium graminearum is the main causative agent of cereal scab and maize cob rot in China. Two hundred and fifty-five F. graminearum isolates were obtained from wheat, barley and maize from Hebei, Heilongjiang and Hubei, provinces with distinct climate conditions and cropping systems. The isolates were confirmed to be F. graminearum by polymerase chain reaction (PCR) assay using F. graminearum speciesspecific primers Fg16F/Fg16R. Two populations, 7C1 and 6A5, were identified to exist in China. The 6A5 population was predominant in Hubei in central China along the Yangtze River, whereas the 7C1 population was predominant in Heilongjiang and Hebei in northern China. Based on sequences of Tri13 and Tri3, genes involved in the mycotoxin biosynthetic pathway, PCR assays were used to detect 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON) and nivalenol (NIV) chemotypes. All three chemotypes of F. graminearum were identified, with 15-ADON chemotype predominating overall. A greater proportion of 3-ADON chemotype was found in Hubei, whereas a greater proportion of 15-ADON was found in Heilongjiang and Hebei