|CLEAR, RANDALL - Canadian Grain Commission|
|O Donnell, Kerry|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/22/2014
Publication Date: 3/22/2014
Citation: Kelly, A.C., Clear, R., Kistler, H.C., O'Donnell, K., McCormick, S.P., Busman, M., Ward, T.J. 2014. Spatio-temporal dynamics of Fusarium head blight and Trichothecene toxin types in Canada [abstract]. Fungal Genetics Conference.
Technical Abstract: In many parts of the world Fusarium graminearum is the primary causal agent of Fusarium head blight (FHB), a disease of cereal crops that adversely affects crop yield, food safety, and animal health. We previously demonstrated population structure associated with differences in trichothecene toxin type (15ADON, 3ADON) and documented dramatic changes in pathogen composition in western Canada. To further understand spatio-temporal dynamics of FHB, we evaluated trichothecene diversity and population assignment of 4,086 F. graminearum isolates collected across Canada 2005-2007. In addition to 15ADON (62%) and 3ADON types (36%), we identified F. graminearum strains capable of producing the recently discovered A-trichothecene, NX-2 (2%) for the first time in Canada. Regional differences in trichothecene frequency were observed, resulting in two longitudinal clines in 3ADON frequency. Temporal patterns also varied regionally, with 3ADON increasing drastically in parts of western Canada, but remaining at relatively low frequency in Ontario and Quebec. Genetic structure remained correlated with toxin type, as the dominant population (NA1) consisted largely of 15ADON isolates, whereas a second population (NA2) consisted largely of 3ADON isolates. However, the rate of population misassignment based on trichothecene type (assignment of 15ADON to NA2 or 3ADON to NA1) increased rapidly, indicating that gene flow is uncoupling trichothecene type from genetic population identity. Gene flow was regionally biased, in that 15ADON misassignment rate was > 3-fold higher than 3ADON misassignment rate in western and Maritime provinces, and in both regions 15ADON misassignment increased over time. In contrast, 3ADON misassignment rate increased annually and was 5-fold higher than 15ADON misassignment rate in eastern provinces. FHB population diversity is being shaped by dramatically different local selective pressures across Canada. Understanding ecological processes contributing to local selection of different FHB pathogens will aid in the development of novel strategies to control FHB and mycotoxins in cereals.