Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/22/2016
Publication Date: N/A
Technical Abstract: During the last decade, a combination of molecular surveillance and population genetic analyses have significantly altered our understanding of Fusarium graminearum, the major FHB pathogen in North America. In addition to the native NA1 population (largely 15ADON toxin type) and the invasive NA2 population (largely 3ADON toxin type), which has rapidly increased in frequency in some areas, isolates with a novel trichothecene toxin type (NX-2) were recently found to cause FHB in the northern U.S. and southern Canada. In this study, we sequenced the genomes of 60 F. graminearum isolates to understand how NX-2 isolates relate to the previously characterized NA1 and NA2 populations; and to identify potential adaptations that distinguish the various populations of F. graminearum responsible for FHB in the U.S. and Canada. Genome-wide patterns of SNP diversity revealed that most isolates with the NX-2 toxin type represent a novel genetic population (termed NA3), although genetic exchange among populations was documented. The three genetic populations were found to differ in gene content, with 122 genes showing population-specific patterns of gene conservation. An additional 16 loci, varying in size from 10-40 kb exhibited patterns of adaptive divergence between pathogen populations. Functional annotation of these population-differentiating genes and genomic regions indicated that F. graminearum populations in North America harbor unique sets of adaptations that contribute to differences in how these pathogens exploit the agricultural landscape.