|O Donnell, Kerry|
Submitted to: Fungal Genetics and Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/5/2008
Publication Date: 11/15/2008
Citation: O Donnell, K., Ward, T.J., Aberra, D., Kistler, H.C., Aoki, T., Orwig, N.G., Kimura, M., Bjornstad, A., Klemsdal, S.S. 2008. Multilocus Genotyping and Molecular Phylogenetics Resolve a Novel Head Blight Pathogen within the Fusarium graminearum Species Complex from Ethiopia. Fungal Genetics and Biology. 45(11):1514-1522.
Interpretive Summary: A number of morphologically similar Fusarium species are capable of inducing the economically devastating Fusarium head blight (FHB) of wheat and barley. In addition to reduction in yields, the fusaria that cause FHB frequently contaminate grain with toxins and estrogenic compounds, rendering them unsuitable for food or feed. In the present study, we surveyed fusaria isolated from stored wheat seeds in Ethiopia for novel FHB species and toxin potential. Results of a unique DNA typing scheme revealed that 22 of the isolates represent a novel FHB species which is described herein as Fusarium aethiopicum. Pathogenicity experiments and mycotoxin analyses demonstrated that isolates of this species could induce FHB of wheat in an environmentally controlled greenhouse and produce trichothecene toxins in vivo. These results should benefit plant breeders who are focused on developing wheat cultivars with broad based resistance to FHB and APHIS quarantine officials by alerting them to the existence of a novel foreign FHB pathogen and a molecular diagnostic tool for its early detection and rapid identification.
Technical Abstract: A survey of Fusarium head blight (FHB)-contaminated wheat in Ethiopia recovered 31 isolates resembling members of the Fusarium graminearum species complex. Results of a multilocus genotyping (MLGT) assay for FHB species and trichothecene chemotype determination suggested that 22 of these isolates might represent a new species within the Fg complex. Phylogenetic analyses of multilocus DNA sequence data resolved the 22 Ethiopian isolates as a novel, phylogenetically distinct species. The new species also appears to be novel in that MLGT probe data and sequence analysis of both ends of the TRI cluster identified 15ADON and NIV recombination blocks, documenting inter-chemotype recombination involving the chemotype-determining genes near the ends of the TRI cluster. Results of pathogenicity experiments and analyses of trichothecene mycotoxins demonstrated that this novel Fg complex species could induce FHB on wheat and elaborate 15ADON in planta. Herein the FHB pathogen from Ethiopia is formally described as a novel species.