The continuing battle between wheat and Fusarium graminearum: understanding the molecular phylogenetic relationships, chemotype diversity and trichothecene biosynthesis gene expression patterns
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".