Fusarium isolates obtained from Iran and Italy were identified by morphological characters and confirmed by using species-specific PCR assays. The genetic chemotyping for each strain, as a preliminary assessment for trichothecene production, was defined using PCR. Subsequently, artificial infection on durum wheat (cv. Normanno) was carried out in the greenhouse to study the pathogenicity and aggressiveness of Iranian, Italian and Syrian F. culmorum strains, the causal agent of crown and root

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... of wheat. All F. culmorum strains from Iran and Italy belonged to the 3-acetyl-deoxynivalenol (3Ac-DON) chemotype, while F. culmorum strains from Syria, previously characterized, belonged to the 3Ac-DON and nivalenol (NIV) chemotypes. All of the strains were pathogenic and caused typical Fusarium crown rot (FCR) symptoms. Italian and Iranian strains showed similar mean aggressiveness levels (19.1 and 18.7% respectively), while the mean aggressiveness level for Syrian strains was 11.8%. There were statistically significant differences among the strains. Two Italian strains, F383 and F1126, had the greatest level of aggressiveness while FC9 (Italian) and F961 (Syrian) were the least aggressive strains. No significant differences relating to agro-ecological origin were detected among Iranian, Italian and Syrian strains. This is the first genetic chemotyping characterization and comparison of F. culmorum strains, isolated from different agro-ecological countries, Iran, Syria (Middle East) and Italy (Europe), which has estimated their potential for producing mycotoxins, and the aggressiveness levels of F. culmorum for development of FCR. These results support the increasing concerns about the risk of FCR in many wheat producing countries, particularly in Iran and Syria.