Title: Biogeography of Trichothecene Chemotypes, and the Origins of North American 3ADON Populations Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: November 4, 2009
Publication Date: November 4, 2009
Citation: Ward, T.J. 2009. Biogeography of Trichothecene Chemotypes, and the Origins of North American 3ADON Populations. Meeting Abstract. Technical Abstract: Previously, we documented a 14-fold increase in 3ADON-producing F. graminearum between 1998 and 2004 in western Canadian provinces. Significant population structure associated with trichothecene chemotype differences was observed, and isolates from the 3ADON populations were found to accumulate significantly more trichothecene and had higher fecundity and growth rates. Expanded molecular surveillance based on 4,266 F. graminearum isolated from seven Canadian provinces between 2005 and 2007 demonstrated the trichothecene chemotype distribution in Canada was characterized by two longitudinal clines. The frequency of 3ADON isolates continued to increase significantly in western Canada between 2005 and 2007. However, similar changes in chemotype frequency among isolates from eastern Canada were not observed. These data suggest a difference in selective pressure acting on FHB pathogens in eastern and western Canada or an uncoupling of the 3ADON chemotype from the trait or traits under selection in some eastern Canadian FHB populations. Analyses of the global population structure of F. graminearum revealed a very close genetic relationship between a Japanese 3ADON population and the novel 3ADON populations in North America. Additional evidence of transcontinental movement of populations followed by limited genetic exchange between resident and introduced populations is presented.