Validation of a modified Petri-dish test to quantify aggressiveness of Fusarium graminearum in durum wheat.

Fusarium graminearum is a common agent causing FHB on wheat throughout the world. Aggressiveness is crucial for understanding the interaction between host-pathogen in the FHB-wheat system. In this paper we modified and validated the Pteri dish test originally described by Masterhazy in 1978, to quantify the aggressiveness of 25 F. graminearum strains using 4 durum wheat cultivars with different resistance levels for FHB. In this study we also demonstrated that germination rate reduction and coleoptile lenght reduction are parameters involved with aggressiveness of F. graminearum. The mean of three disease parameters from the modified Petri dish method is introduced in this paper as a new parameter for aggressiveness and named Petri dish aggressiveness index. The results obtained reveal that this modified Petri dish test is reliable, rapid and stable with different durum wheat cultivars and yields highly significant correlation coefficients with floret and ear inoculations, thus it is suitable to be used for quantification of aggressiveness of F.graminearum.