Identification of deoxynivalenol and nivalenol producing chemotypes of Fusarium graminearum isolates from durum wheat in a restricted area of Northern Italy.

Fusarium graminearum is one of the main causal agents of fusarium head blight (FHB) in Italy. A population of 74 F. graminearum strains was collected from symptomatic durum wheat spikes from different fields around Bologna (Emilia-Romagna, northern Italy) between 2006 and 2008. The data obtained showed that the F. graminearum population is variable in an homogeneous restricted geographical area. F. graminearum sensu stricto strains were examined using specific primers for chemotypes based on the production of the trichothecenes deoxynivalenol (DON) and nivalenol (NIV). The strains were analyzed by multiplex PCR in the Tri12 sequence of the trichothecene gene cluster and assigned to one of three profiles of trichothecene chemotypes. All three fungal chemotypes were found. The 15-acetyldeoxynivalenol (15ADON) chemotype was the most frequent (87.2%), followed by the 3-acetyldeoxynivalenol (3ADON) (8.1%) and NIV (2.7%) chemotypes. The variability of the strains in such a restricted area leads us to hypothesize that there is similar variability of F. graminearum throughout Italy.