The evolution of symbiont preference traits in the model legume <i>Medicago truncatula</i>
Bibliographic record
Abstract
Many hosts preferentially associate with or reward better symbionts, but how these symbiont preference traits evolve is an open question. Legumes often form more nodules with or provide more resources to rhizobia that fix more nitrogen (N), but they also acquire N from soil via root foraging. It is unclear whether root responses to abiotically and symbiotically derived N evolve independently. Here, we measured root foraging and both preferential allocation of root resources to and preferential association with an effective vs an ineffective N-fixing Ensifer meliloti strain in 35 inbred lines of the model legume Medicago truncatula. We found that M. truncatula is an efficient root forager and forms more nodules with the effective rhizobium; root biomass increases with the number of effective, but not ineffective, nodules, indicating preferential allocation to roots harbouring effective rhizobia; root foraging is not genetically correlated with either preferential allocation or association; and selection favours plant genotypes that form more effective nodules. Root foraging and symbiont preference traits appear to be genetically uncoupled in M. truncatula. Rather than evolving to exclude ineffective partners, our results suggest that preference traits probably evolve to take better advantage of effective symbionts.
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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 | 0.001 | 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".