Heterologous expression and activity of Ptr ToxB from virulent and avirulent isolates of<i>Pyrenophora tritici-repentis</i>
Bibliographic record
Abstract
The fungal pathogen Pyrenophora tritici-repentis causes tan spot, an important foliar disease of wheat (Triticum aestivum). The fungus produces at least three host-specific toxins, including the chlorosis-inducing Ptr ToxB, a small protein encoded by the ToxB gene. A ToxB homolog is also found in race 4 isolates of P. tritici-repentis, which lack detectable toxin activity. It is not clear whether the absence of toxin activity in these isolates stems from differences in the ToxB gene sequence and (or) level of expression. To directly compare the chlorosis-inducing activity of different forms of Ptr ToxB, ToxB from a virulent race 5 isolate (Alg3-24) and a ToxB homolog from an avirulent race 4 isolate (90-2) were heterologously expressed as glutathione-S-transferase (GST)- and hexahistidine (His)-tagged fusion proteins in Escherichia coli. Infiltration of toxin solutions into the leaves of Ptr ToxB sensitive and insensitive wheat seedlings revealed that the overexpressed GST- and His-tagged toxin from Alg3-24 induced strong chlorosis symptoms in a genotype-specific manner, whereas the form of the toxin from isolate 90-2 induced only trace amounts of symptoms. This suggests that the absence of chlorosis-inducing activity in race 4 of P. tritici-repentis may be largely due to sequence differences in ToxB at the gene and protein level, regardless of the extent of gene expression.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".