Genome characterization of <i>Pyrenophora tritici‐repentis</i> isolates reveals high plasticity and independent chromosomal location of <i>ToxA</i> and <i>ToxB</i>
Bibliographic record
Abstract
The fungus Pyrenophora tritici-repentis (Died.) causes tan spot, an important leaf disease of wheat worldwide. Isolates of this pathogen have been collected and characterized into eight races on the basis of their ability to produce three different host-selective toxins. The karyotype of 47 isolates was determined by pulsed field gel electrophoresis. The collection originated from different parts of the world and included genotypes from all races. A single isolate was characterized for each of races 3, 4 and 6, whereas fourteen, five, nine, five and eleven isolates were karyotyped for races 1, 2, 5, 7 and 8, respectively. The survey showed that the chromosome number of P. tritici-repentis was highly variable, with some isolates having as few as eight chromosomes, but others having 11 or more. Similarly, the genome size ranged from 25.5 to 48.0 Mb, and individual chromosome sizes ranged from 1.3 to more than 5.7 Mb. Considerable variation was observed in karyotype patterns among the P. tritici-repentis isolates tested. A total of 29 different karyotypes was identified among the 47 isolates. These chromosome level variations were as variable for isolates within a race as for isolates across races. Southern blot analysis of the 47 isolates with ToxA and ToxB probes revealed that the toxin genes were always located on different chromosomes. Furthermore, with six chromosome-specific single-copy probes, the ToxA-carrying chromosome was shown to be homologous among the Ptr ToxA-producing isolates, with a related chromosome in the non-ToxA-producing isolates, suggesting that the chromosome on which ToxA generally resides is of an essential nature. Interestingly, a molecular rearrangement involving a translocation of ToxA to a different chromosome was identified in one isolate.
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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 | 0.000 | 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) | 0.001 | 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".