Occurrence of copper-resistant strains and a shift in <i>Xanthomonas</i> spp. causing tomato bacterial spot in Ontario
Bibliographic record
Abstract
Field strains of tomato bacterial spot pathogen (Xanthomonas euvesicatoria, X. vesicatoria, X. perforans, and X. gardneri) were characterized for sensitivity to copper and species composition. A total of 98 strains were isolated from symptomatic leaf and fruit samples collected from 18 tomato fields in Ontario. In greenhouse pathogenicity tests, most of the field strains caused severe (37 strains) to highly severe (23 strains) symptoms on 'Bonny Best' tomato plants, whereas 38 strains caused moderate symptoms. In MGY agar plates amended with various concentrations of copper sulfate, 11 strains were completely sensitive (no growth) and 87 strains were resistant (grew on 1.0 mmol/L or higher copper concentration). PCR analysis of the hrp gene cluster followed by restriction digestion with HaeIII and sequencing identified X. gardneri (35 strains) and X. perforans (26 strains) as predominant species and X. euvesicatoria and X. vesicatoria as less common species in Ontario tomato fields. Separation of field strains into various species was also confirmed with starch hydrolysis activity on agar medium. Moreover, 72 field strains produced shiny greenish-yellow colonies surrounded by a milky zone on xanthomonad differential (Xan-D) medium, and the colonies of 26 strains did not produce a milky zone. Thirty-four strains could not be clustered into any species and 25 of those strains were negative for the hrp gene PCR and also did not produce a milky zone around colonies on Xan-D medium. Our results suggest a widespread existence of copper-resistant strains and an increase in X. perforans strains of bacterial spot pathogen in Ontario. This information on copper resistance and species composition within bacterial spot pathogens in Ontario will be helpful for developing effective disease management strategies, making cultivar selection, and breeding new tomato cultivars.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 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".