Bacterial-Mediated Induced Resistance in Cucumber: Beneficial Effect of the Endophytic Bacterium <i>Serratia plymuthica</i> on the Protection Against Infection by <i>Pythium ultimum</i>
Why this work is in the frame
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Bibliographic record
Abstract
ABSTRACT The potential of the endophytic bacterium Serratia plymuthica strain R1GC4 in stimulating defense reactions in cucumber (Cucumis sativus) seedlings inoculated with the soilborne pathogen Pythium ultimum was explored at the cellular level. Bacterial treatment prior to Pythium inoculation resulted in less seedling disease development as compared with that in nontreated control plants, in which typical root symptoms were visible by 3 days after inoculation with the pathogen. Histological investigations of root samples revealed striking differences in the extent of plant defense reactions between bacterized and nonbacterized plants. These observations were further confirmed at the ultrastructural level with the demonstration that restriction of fungal colonization to the outermost root tissues of bacterized seedlings correlated with the deposition of enlarged callose-enriched wall appositions at sites of potential pathogen penetration and the accumulation of an osmiophilic material in the colonized areas. Hyphae of the pathogen, surrounded by this electron-opaque material, exhibited considerable changes including cytoplasm disorganization and, in many cases, loss of the protoplasm. However, labeling with the beta-1,4-exoglucanase resulted in a regular labeling of Pythium cell walls, even at a time when these walls were entirely coated by the osmiophilic material. This material was also found to infiltrate into the invading hyphae to form either an internal coating of the cell wall or a network of polymorphic droplets in the area previously occupied by the cytoplasm. Cytochemical investigations revealed that callose, pectin, and cellulose appeared in the wall appositions. In addition, glucosides, lipids, and phenolics were detected in the electron-dense aggregates forming the core of most wall appositions. Finally, galactose residues were among the minor polysaccharidic compounds detected in the wall appositions. Evidence is provided in this study showing that treatment with S. plymuthica sensitizes susceptible cucumber plants to react more rapidly and more efficiently to Pythium attack through the formation of physical and chemical barriers at sites of potential fungal entry.
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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 | 0.001 |
| 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 it