ARS | Publication request: GLOBAL MOLECULAR SURVEILLANCE REVEALS NOVEL FUSARIUM HEAD BLIGHT SPECIES AND TRICHOTHECENE TOXIN DIVERSITY

Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 2, 2007
Publication Date: November 1, 2007
Citation: Starkey, D.E., Ward, T.J., Aoki, T., Gale, L.R., Kistler, H.C., Geiser, D.M., Suga, H., Toth, B., Varga, J., O Donnell, K. 2007. Global molecular surveillance reveals novel Fusarium head blight species and trichothecene toxin diversity. Fungal Genetics and Biology. 44(11):1191-1204.

Interpretive Summary: We conducted a genetic screen of 2,100 fungal pathogens that cause the economically devastating disease of wheat and barley called Fusarium Head Blight (FHB) to better understand their global genetic diversity and toxin potential. In addition to causing significant reductions in yields, these pathogens also contaminate cereals with estrogenic compounds and toxins, both of which impact negatively on plant, animal and human health and food safety. Our genetic analyses led to the discovery of two new FHB pathogens, one in Japan and Hungary and the other in the United States. In addition, a highly divergent population of another FHB pathogen was discovered along the Gulf Coast of the United States. Toxin analyses revealed that the newly discovered FHB pathogens within the U.S. produce toxins heretofore thought to be rare or absent within North America. Results of this study provide critical information on ecology and population dynamics of these FHB pathogens that are urgently needed to formulate rationale disease management, plant breeding and quarantine strategies.

Technical Abstract: In order to extend our current knowledge of Fusarium Head Blight (FHB) pathogen and trichothecene toxin diversity worldwide, we collected and analyzed partial translation elongation factor-1alpha and reductase gene sequences from 2,100 isolates from a global collection spanning five continents. Results of this preliminary genetic screen identified sixteen genetically distinct isolates. In order to investigate their species limits, phylogenetic analyses of these isolates, together with 42 strains chosen to represent the known genetic diversity of the B-trichothecene toxin-producing clade, were expanded to include portions of 13 genes from 8 loci totaling 16.3 kb of DNA sequence data. These analyses led to the discovery of two novel FHB pathogens, formally described herein at the rank of species, a highly divergent population of Fusarium graminearum currently only known from the Gulf Coast of the United States, and phylogenetically divergent isolates of F. acaciae-mearnsii from Australia and South Africa.