<i>ras2</i> Controls Morphogenesis, Pheromone Response, and Pathogenicity in the Fungal Pathogen <i>Ustilago maydis</i>
Bibliographic record
Abstract
Ustilago maydis, a pathogen of maize, is a useful model for the analysis of mating, pathogenicity, and the morphological transition between budding and filamentous growth in fungi. As in other fungi, these processes are regulated by conserved signaling mechanisms, including the cyclic AMP (cAMP)/protein kinase A (PKA) pathway and at least one mitogen-activated protein kinase (MAP kinase) pathway. A current challenge is to identify additional factors that lie downstream of the cAMP pathway and that influence morphogenesis in U. maydis. In this study, we identified suppressor mutations that restored budding growth to a constitutively filamentous mutant with a defect in the gene encoding a catalytic subunit of PKA. Complementation of one suppressor mutation unexpectedly identified the ras2 gene, which is predicted to encode a member of the well-conserved ras family of small GTP-binding proteins. Deletion of the ras2 gene in haploid cells altered cell morphology, eliminated pathogenicity on maize seedlings, and revealed a role in the production of aerial hyphae during mating. We also used an activated ras2 allele to demonstrate that Ras2 promotes pseudohyphal growth via a MAP kinase cascade involving the MAP kinase kinase Fuz7 and the MAP kinase Ubc3. Overall, our results reveal an additional level of crosstalk between the cAMP signaling pathway and a MAP kinase pathway influenced by Ras2.
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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) | 0.001 | 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".