Investigations on the presence of Fusarium species, chemotype characterization and trichothecene mycotoxin determination in soft and durum wheat in Umbria.

A study was conducted on 162 grain samples of durum and soft wheat harvested in 2009 and 2010 in different areas of the Umbria region. Samples were subject to fungal isolation on PDA and to the determination of the principal infecting fungi. Isolates belonging to the Fusarium genus were identified by PCR. In addition, a representative sub-sample of F. graminearum and F. culmorum strains was subject to the determination of 15ADON, 3ADON and NIV chemotypes by multiplex-PCR. Furthermore, the main type A (T-2 and HT-2 toxins and DAS) and type B (DON and NIV) trichothecenes were analyzed by LC-MS/MS. Fungal isolations showed that Fusarium spp. were present in all the samples, with incidence peaks of about 80%. PCR identification showed that, with the exception of soft wheat sampled in 2009, F. graminearum was the most frequently isolated species. In 2009, a year characterized by unfavourable climatic conditions for the development of the main causal agents of Fusarium head blight, the occurrence of F. avenaceum and F. poae was higher than in 2010. On the contrary, the incidence of F. graminearum was higher in 2010 than in 2009. Multiplex-PCR analyses showed that all F. culmorum strains were 3ADON producers, while, among F. graminearum strains, the 15ADON chemotype was the most frequent (68%), followed by NIV (19%) and 3ADON (13%) chemotypes. Mycotoxin analyses showed a high incidence of type B trichothecenes, even if DON levels never exceeded the EU legal limits. Relationships between isolated Fusarium species and the analyzed mycotoxins are discussed.