Virulence of <i>Chalara elegans</i> on bean leaves, and host-tissue responses to infection
Bibliographic record
Abstract
Chalara elegans (syn. Thielaviopsis basicola) is a soilborne plant pathogen with a wide host range, which initially establishes a hemibiotrophic relationship, following infection of its host. To assess the differences in virulence among isolates and to study colonization of host tissues, detached bean leaves were used in an inoculation assay. Two-week-old ‘Kentucky Wonder’ leaves were sprayed with 0.8–1.0 mL of inoculum (105 phialospores/mL) and incubated under moist conditions for 5 days at 20–23 °C. Necrotic lesions that developed were enumerated and measured for 27 isolates of C. elegans from a broad range of hosts and geographic locations. Lesion numbers were affected by culture age, with 2-week-old cultures providing the most lesions compared with older cultures. There were pronounced differences in virulence among isolates, which were correlated with differences in colony morphology. The isolates were grouped into high, moderate, and low virulence classes based on the number of lesions produced. Highly virulent isolates were darkly pigmented, while moderately and weakly virulent isolates had reduced colony pigmentation. Bean cultivars influenced the number of lesions that developed, and ‘Kentucky Wonder’ was the most susceptible compared with ‘Royal Burgundy’ and ‘Kentucky Blue’. In infected leaf tissues, the pathogen was initially localized to epidermal cells, which became necrotic and accumulated phenolic compounds. Callose deposits, cell-wall thickening, and accumulation of polyphenol oxidase were also observed in these epidermal cells after 36–48 h. Spread of hyphae to underlying mesophyll cells occurred after 48–72 h. Chlamydospores and phialospores developed on lesions within 5 days after inoculation. Most lesions were limited in size to less than 1 mm and resembled local lesions resulting from a virus inoculation. The ability of C. elegans to infect and induce defense responses in bean leaves has not been previously reported. This host-pathogen system provides an interesting model for further studies on the cellular responses and potentially induced resistance in beans, resulting from a soilborne pathogen.
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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".