Fusarium head blight (FHB) continues to threaten the economic sustainability of wheat and barley production in Canada and worldwide. The overall goal of this thesis is to expand our current knowledge of the FHB pathogen, Fusarium graminearum and its trichothecene chemotype diversity. Continuous monitoring of trichothecene chemotypes may well inform on the potential risk and the type of Fusarium populations present in a given region. Fusarium populations in Winnipeg and Carman, Manitoba were examined using chemotype as a marker in the field. Rapid expansion of the 3-acetyldeoxynivalenol (3-ADON) chemotype was observed in Winnipeg and Carman. 3-ADON chemotype is consistently found at high frequencies over the previously common 15-acetyldeoxynivalenol (15-ADON) chemotype, suggesting that the shift in pathogen populations is continuing. This study provides the first evidence on the presence of nivalenol (NIV) producing F. cerealis strains in winter wheat in Manitoba, Canada. Therefore, discovery of NIV producing F. cerealis in wheat poses a serious concern for the wheat industry in Canada. Phylogenetic, chemotypic, phenotypic, and pathogenic abilities of 150 strains of F. graminearum species complex (FGSC) from eight countries were investigated. Type and amount of trichothecenes produced by a strain are key factors in determining the level of aggressiveness of that strain regardless of its species origin. The sequence variations of TRI8 gene in different species in the FGSC were examined as Fusarium species may produce different types of trichothecenes depending on differences in the core trichothecene (TRI) cluster genes. The TRI8 haplotypes did group according to chemotype rather than by species, indicating that 3-ADON, 15-ADON and NIV chemotypes have a single evolutionary origin. Comparison of TRI gene expression demonstrated that accumulation of TRI transcripts was higher in 3-ADON producing strains compared to 15-ADON and NIV strains. The presence of masked mycotoxins deoxynivalenol-3-glucoside (D3G) in food and feed is an increasing concern. Canadian spring wheat cultivars inoculated with different chemotypes produce D3G upon Fusarium infection and moderately resistant/intermediate cultivars showed higher D3G/DON ratio compared to susceptible cultivars. / October 2016
| Identifer | oai:union.ndltd.org:MANITOBA/oai:mspace.lib.umanitoba.ca:1993/31596 |
| Date | 08 1900 |
| Creators | Chami, Amarasinghe |
| Contributors | Fernando, Dilantha (Plant Science), Brûlé-Babel, Anita (Plant Science) Sharanowski, Barbara (Entomology) Piercey-Normore, Michele (Biological Sciences) Ravindra, Chibbar (University of Saskatchewan) |
| Publisher | John Wiley and Sons- Plant Pathology |
| Source Sets | University of Manitoba Canada |
| Detected Language | English |
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