Determination of deoxynivalenol and nivalenol producing chemotypes of Fusarium graminearum isolated from durum wheat in Italy.

Durum wheat production in Italy is economically of great importance. Fusarium graminearum is the main fusarium head blight (FHB) causal agent in wheat, reducing both yield and grain quality. F. graminearum produces several mycotoxins and, among trichothecenes, deoxynivalenol (DON) and nivalenol (NIV) are the most studied for their toxicity towards humans and animals. DON-producing isolates can be further distinguished on the basis of the predominant acetyl-DON derivative in 3-acetyldeoxynivalenol (3-ADON) or 15-acetyldeoxynivalenol (15-ADON). In order to evaluate possible mycotoxin contamination risks in food, it is very important to know which chemotype is the prevalent in a F. graminearum population. F. graminearum sensu stricto strains were collected from symptomatic durum wheat heads and grains of several naturally infected fields located mostly in Emilia - Romagna, The Marche, Lazio, Tuscany and Umbria. A multiplex PCR in the region of genes Tri12, located in the terminal gene cluster of trichothecenes, was used to characterize 187 single-spore isolates of F. graminearum as NIV, 3-ADON and 15-ADON chemotypes. All the three chemotypes were present in the F. graminearum population studied. The most frequent chemotype was 15-ADON (83.4%), followed by 3-ADON (10.7%) and NIV (5.9%). NIV-producing isolates were found only in Emilia-Romagna (3.5%), Umbria (33.3%) and The Marche (5.7%).