IDENTIFICATION OF FUSARIUM SPECIES OCCURRING ON CONTAMINATED CEREALS SAMPLED WORLDWIDE

Cereals represent the major staple food for many people at worldwide level. Among the diseases that affect these crops, the occurrence of Fusarium species is related to the highest risk for the consumers since many Fusarium can produce a wide range of harmful mycotoxins that can be accumulated in the cereal kernels. In particular, Fusarium Head Blight of wheat and other minor cereals is caused by a complex of species, each provided of specific mycotoxin profiles. Moreover, the main species can vary in the different geographic areas because they can be influenced from the changing environmental conditions. Therefore, a reliable identification of the most occurring species is important for the correct evaluation of the potential toxicological risk of contaminated kernels. 320 samples of wheat and barley were collected in Austria (2011-2012), Germany (2012) and China (2013) and analyzed for the multi-mycotoxin by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and related toxigenic fungi contamination. Among the Fusarium mycotoxins mainly detected in 100 wheat samples from China, enniatins (ENNs), deoxynivalenol (DON), its glucoside DON-3-glucoside (D3G), 3- acetyl- deoxynivalenol (DON), zearalenone (ZEN), nivalenol and, only in 6% of samples, fumonisins (FUMs) were identified, with a high number of other mycotoxins occurring at low concentrations detected. Also in Germany and Austria, the range of mycotoxins detected in wheat and barley was high, being beauvericin (BEA), ENNs, DON, D3G and ZEN the most detected mycotoxins. This wide contamination by mycotoxins of the samples was also reflected in the wide variability of Fusarium species isolated and identified. Fungal strains were first identified based on their morphological features and therefore confirmed by sequencing calmodulin and elongation factor 1? genes. In wheat collected in China, F. graminearum sensu stricto, F. verticillioides, and species of F. incarnatum/equiseti complex were the most frequently isolated. In Germany and Austria, in both barley and wheat, F. graminearum sensu stricto, F. poae, F. acuminatum and F. tricinctum were the most occurring species. Moreover, a population of strains phylogenetically equally distant from F. acuminatum and F. tricinctum was also characterized from both crops, showing a high level of genetic diversity. However, more genetic analyses are needed to evaluate if this latest population is a new genetic entity to be described within the genus Fusarium.