Characterization of virulence and PCR-DGGE profiles of Fusarium avenaceum from western Canadian Prairie Ecozone of Saskatchewan

Fusarium avenaceum isolates causing fusarium head blight (FHB) in wheat were collected from the Canadian Prairies and Mixed Wood Plains Ecozones. A total of 91 isolates were grouped into 15 phenotypes and 10 VCGs which formed seven ITS rDNA phylogenetic clades and three EF-1 PCR-DGGE groups. Variation in virulence within F. avenaceum isolates ranged from high to avirulent on wheat. In general, virulent isolates demonstrated greater host range and geographic distribution, while avirulent isolates had a limited spread. Virulent isolates demonstrated greater heat tolerance, colour plasticity and growth rate compared with avirulent isolates. Overall, data indicate that pathogen dynamics and outbreaks might be influenced by the abundance ratio of virulent/avirulent isolates related to climate characteristics of each agro-region. The characterization of F. avenaceum 'sensu lato' isolates, obtained from western and eastern ecozones, provided baseline information on the variation that exists for this FHB-causing species. Combined with environmental or ecological information, this knowledge could establish a consistent, long-term management of the pathogen.