Increased α-ketoglutarate as a missing link from the C <sub>3</sub> -C <sub>4</sub> intermediate state to C <sub>4</sub> photosynthesis in the genus <i>Flaveria</i>
Bibliographic record
Abstract
ABSTRACT As a complex trait, C 4 photosynthesis has multiple independent origins in evolution. Phylogenetic evidence and theoretical analysis suggest that C 2 photosynthesis, which is driven by glycine decarboxylation in the bundle sheath cell, may function as a bridge from C 3 towards C 4 photosynthesis. However, the exact molecular mechanism underlying the transition between C 2 photosynthesis towards C 4 photosynthesis remains elusive. Here, we provide multiple evidence suggesting a role of higher α-ketoglutarate (AKG) concentration during this transition. Metabolomic data of 12 Flaveria species, including multiple photosynthetic types, show that AKG concentration initially increases in the C 3 -C 4 intermediate with a further increase in C 4 species. Petiole feeding of AKG increased the concentrations of C 4 related metabolites in C 3 -C 4 and C 4 species but not the activity of C 4 related enzymes. Sequence analysis shows that glutamate synthase (Fd-GOGAT), which catalyzes the generation of glutamate using AKG, was under strong positive selection during the evolution of C 4 photosynthesis. Simulations with a constraint-based model for C 3 -C 4 intermediate further show that decreasing the activity of Fd-GOGAT facilitates the transition from a C 2 -dominant to a C 4 -dominant CO 2 concentrating mechanisms. All these provide an insight into the mechanistic switch from C 3 -C 4 intermediate to C 4 photosynthesis.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.000 | 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) | 0.001 | 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".