Competence, determination, and meristemoid plasticity in tobacco organogenesis in vitro
Bibliographic record
Abstract
Tobacco leaf explants can produce both shoots and roots depending on the phytohormones in the medium. These arise directly via meristemoids (meristematic centers), which form distinct primordia and then organs. In this study it was found that shoot primordia arose from the palisade mesophyll cells at the adaxial surface, while root primordia arose from the rib parenchyma cells, near the existing vascular bundles. In studies on competency and determination, it was found that the tobacco leaf explants required 46 days in culture on a shoot-inducing medium (SIM) to become determined for shoot formation, while the explants were competent for rooting at excision and needed only 1 day on the root-inducing medium (RIM) to become determined for root formation. Transfer of explants from SIM or RIM to basal medium (BM without phytohormones) and vice versa supported the above findings. Transfer of explants from SIM to RIM and vice versa, delayed the timing of root and shoot formation, but not the position in the explant from which the organs arose. On transfer from SIM to RIM or vice versa, meristemoids that were already determined for shoot or root formation continued to develop, while those not yet determined were inhibited and (or) reverted to parenchymatous tissue. Thus under our culture conditions meristemoids in tobacco leaf explants are not plastic.Key words: competence, determination, meristemoid plasticity, organogenesis, tobacco.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".