Genetic diversity of Fusarium species, causal agents of wheat root and crown rots using molecular markers and pathogenicity tests

During 2009-10, wheat fields in eight provinces of Iran including Tehran, Esfahan, Ardabil, Golestan, Mazandaran, Markazi, Qazvin and Zanjan were surveyed and samples were collected from plants showing crown rot disease symptoms. Fusarium species were identified based on morphological features and molecular markers (SCAR). Twelve Fusarium species including F. culmorum, F. pseudograminearum, F. equiseti, F. nygamai, F. proliferatum, F. oxysporum, F. solani, F. pseudonygamai, F. sambucinum, F. acuminatum, F. lateritium and F. verticillioides were identified. F. culmorum was the dominant species and had the highest (32%) frequency, followed by F. pseudograminearum (18%). Genetic diversity of 64 representative isolates of F. culmorum was studied using eight Simple Sequence Repeat (SSR) markers. There was a high level (0.81) of genetic diversity within the total population, where 89% of the variability was distributed within populations and 11% among populations. Number of alleles was between 7 to 22. In addition, there was significant difference among isolates in their aggressiveness. Isolates with a high level of aggressiveness from different geographical areas can be used for screening resistance to F. culmorum.