Complex Regulation of Proanthocyanidin Biosynthesis in Plants by R2R3 MYB Activators and Repressors
Bibliographic record
Abstract
MYB transcription factors are central players in the regulation of phenylpropanoid and flavonoid metabolism. In proanthocyanidin and anthocyanin biosynthesis, MYBs act within a MBW (MYB-bHLH-WD40) complex. However, the MYB provides the specificity and ultimately determines where in the plant these pathways are activated. While work on the transcriptional regulation of proanthocyanidin biosynthesis in Arabidopsis seed coat has been instrumental in the discovery of MYB transcription factors, research in other plants such as grapevine and poplar has also made substantial contributions. In these systems, several types of MYB transcriptional activators of proanthocyanidin biosynthesis in poplar have been described, which in turn induce the expression of MYB repressors. The role of the MYB repressors may be to help modulate stress-induced PA synthesis, or to fine-tune flavonoid and phenylpropanoid metabolism. Characterizing both types of MYB genes via transgenic overexpression and promoter activation assays in transiently transformed cells has allowed us to construct a model for this gene regulatory network of MYB activators and repressors for regulation of proanthocyanidins in poplar. A long-term aim is to understand the mechanisms of repressor action, and to identify the linkages to upstream signals or environmental stimuli that induce proanthocyanidin accumulation.
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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 | 0.000 | 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) | 0.003 | 0.001 |
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".