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

In Italy durum wheat production is economically of great importance. Fusarium graminearum [teleomorph Gibberella zeae] is the main Fusarium Head Blight (FHB) causal agent in wheat, reducing both yield and grain quality. F. graminearum produces several mycotoxins and, among the 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-AcDON) or 15-acetyldeoxynivalenol (15-AcDON) chemotypes. Species determination and genetic chemotyping of F. graminearum strains were used to understand their spatial distribution in Italy. F. graminearum sensu stricto strains were collected from symptomatic durum wheat heads and grains of several naturally infected fields mainly located in Emilia–Romagna, Marche, Toscana, Umbria from 2006 to 2009. A multiplex PCR in the region of Tri12 gene, located in the terminal gene cluster of trichothecenes, was used to characterize 187 single-spore isolates of F. graminearum as NIV, 3-AcDON and 15-AcDON chemotypes. All the three chemotypes were present in F. graminearum population studied. The 15-AcDON chemotype was dominant, representing 83.4% of the examined strains, followed by 3-AcDON (10.7%) and NIV (5.9%). 15-AcDON producing isolates were found in the majority of Italian regions. These data are comparable with those reported by several authors all over the world. Our data further confirm that the 3-AcDON chemotype is less present in Italy. NIV producing isolates has been found in Emilia-Romagna (3.5%), Umbria (33.3%) and Marche (5.7%). The knowledge of the prevalent chemotype in a F. graminearum population in wheat is very important to improve the prediction of toxin contamination.