Identification of a DNA region associated with the cool virulence of Ralstonia solancearum strain UW551 and its utilization for specific detection of the bacterium’s race 3 biovar 2 strains
Bibliographic record
Abstract
The cool virulent Ralstonia solanacearum race 3 biovar 2 (r3b2) strains cause destructive brown rot of potato. They are quarantined pathogens in Europe and Canada and select agent pathogens in the United States. We previously identified r3b2 (sequevars 1 and 2)-unique fragments that clustered into 32 regions in the genome of R. solanacearum. In this study, we targeted five of those regions for mutagenesis in order to determine whether they are involved in cool temperature-related biological functions for diagnostic purpose. Knockout mutants of four regions produced no changes to the biology of the r3b2 strain UW551. The mutation of region 13, which is 3,407 bp in size, resulted in significantly reduced twitching motility, attachment to the roots of tomato seedlings, and virulence under cool temperature conditions (18-24°C), although no significant difference was found under warm temperature conditions (24-30°C) as compared to the wild type strain. As a result, we designed primer pair Rs-CV-F and Rs-CV-R to target the region 13 for specific detection of r3b2 strains of R. solanacearum. Our assay specifically detected all the 34 r3b2 strains and none of the 56 non-r3b2 strains of R. solanacearum, nor any other five plant- or soil-associated bacteria including Enterobacter cloacae, Pseudomonas syringae pv. syringae, Xanthomonas campestris pv. campestris, X. citri, and R. pickettii. Unexpectedly, in silico analysis predicted that a recently deposited non-sequevar 1 or 2 Brazilian R. solanacearum strain RS489 would be recognized by our assay and by previously published r3b2-specific assays, although the cool-virulent status of this strain is unclear. Our PCR assay is the first to target a DNA region associated with cool-virulence that makes r3b2 strains highly regulated pathogens for specific detection of this important group of R. solanacearum.
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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".