Citramalate synthase yields a biosynthetic pathway for isoleucine and straight- and branched-chain ester formation in ripening apple fruit
Bibliographic record
Abstract
Significance Fruit aroma influences herbivory and food choice by humans, ultimately affecting seed dispersal and plant reproductive success. Despite the significance of scent, our understanding of the biosynthesis of odor-active volatiles is incomplete. Herein, we detail a plant pathway that uses pyruvate and acetyl-CoA to form citramalic acid and, through a series of recursive reactions that bypass regulation at threonine deaminase, enables 1-C α-ketoacid elongation and synthesis of isoleucine and straight and branched chain esters. The initiating enzyme, citramalate synthase, is a neofunctionalized form of 2-isopropylmalate synthase that is insensitive to feedback inhibition. Engagement of the “citramalate pathway” in ripening fruit provides for an elevated and persistent production of isoleucine and volatile esters as fruit tissues ripen, age, and senesce.
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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 | 0.001 | 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".