PBS3 is the missing link in plant-specific isochorismate-derived salicylic acid biosynthesis
Bibliographic record
Abstract
Abstract The phytohormone salicylic acid (SA) is a central regulator of plant immunity. Despite such functional importance, our knowledge of its biosynthesis is incomplete. Previous work showed that SA is synthesized from chorismic acid in plastids. The bulk of pathogen-induced SA derives from isochorismate generated by the catalytic activity of ISOCHORISMATE SYNTHASE1 (ICS1). How and in which cellular compartment isochorismate is converted to SA is unknown. Here we show that the pathway downstream of isochorismate requires only two additional proteins: the plastidial isochorismate exporter ENHANCED DISEASE SUSCEPTIBILITY5 (EDS5) and the cytosolic amido-transferase AvrPphB SUSCEPTIBLE3 (PBS3). PBS3 catalyzes the conjugation of glutamate to isochorismate. The reaction product isochorismate-9-glutamate spontaneously decomposes into enolpyruvyl- N -glutamate and SA. This previously unknown reaction mechanism appears to be conserved throughout the plant kingdom. One Sentence Summary Salicylic acid is synthesized via isochorismate-9-glutamate by PBS3.
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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 | 0.001 |
| 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 | 0.001 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.011 | 0.007 |
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".