Chlorophyllide <i>a</i> oxygenase (CAO) gene duplication across the Viridiplantae
Bibliographic record
Abstract
Abstract Viridiplantae, a diverse group of green plants and alga that have evolved from a common ancestor, are unified in their ability to produce and use two types of chlorophyll (chlorophyll a and chlorophyll b ) to capture light energy. In addition to playing a role in light harvesting, chlorophyll b is required at the appropriate level for the accumulation, assembly, and stability of light harvesting complexes within the photosynthetic apparatus. Chlorophyll b is synthesized from chlorophyll a by the enzyme chlorophyllide a oxygenase (CAO), a Rieske-type mononuclear non-heme iron oxygenase. A regulatory degron sequence, described in detail only in land plants, regulates the stability of CAO proteins based on the availability of chlorophyll b. Recent identification of CAO gene duplication in bryophyte and green algal species, combined with expanded availability of sequenced genomes within the Viridiplantae, prompted further investigation into the role of gene duplication in the evolution of chlorophyll b biosynthesis. Examination of genomes from 246 plant and algae species revealed independently occurring CAO duplications throughout the Viridiplantae, with a higher prevalence of duplication in land plants compared to their algal relatives. Additionally, we demonstrate that the degron sequence is poorly conserved in chlorophytes, but first appears as a conserved sequence in charophytes, and is very highly conserved among the embryophytes. The evolutionary history and functional role of CAO throughout the Viridiplantae lineage is discussed based on these key observations, adding to our understanding of chlorophyll b biosynthesis and the role of CAO in photosynthetic species.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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".