Modulation of embryo-forming capacity in culture through the expression of Brassica genes involved in the regulation of the shoot apical meristem
Bibliographic record
Abstract
Somatic embryogenesis in Arabidopsis is achieved by culturing bending-cotyledon embryos on a 2,4-D-containing induction medium for 14 d followed by a transfer on to a hormone-free development medium. Several genes orthologous to Arabidopsis SHOOTMERISTEMLESS (STM), CLAVATA 1 (CLV1), and ZWILLE (ZLL) were isolated from Brassica oleracea (Bo), B. rapa (Br), and B. napus (Bn), and ectopically expressed in Arabidopsis to assess their effects on somatic embryogenesis. Ectopic expression of BoSTM, BrSTM, and BnSTM increased the number of somatic embryos, whereas a different effect was observed in lines overexpressing BnCLV1 in which somatic embryo formation was severely repressed. The introduction of BnZLL did not have any effects on Arabidopsis somatic embryogenesis. The increased embryo-forming capacity observed in lines overexpressing Brassica STM was associated with a lower requirement for the inductive signal 2,4-D, and a higher expression of WUSCHEL (WUS) which demarcates the formation of embryogenic cells. This was in contrast to the 35S::BnCLV1 lines which showed the highest requirement for exogenous 2,4-D and a reduced WUS expression. Microarray studies were conducted to monitor global changes in transcript levels during Arabidopsis somatic embryogenesis between the wild-type (WT) line and a BoSTM-overexpressing line, which showed the most pronounced enhancement of somatic embryo yield. The introduction of BoSTM affected the expression of many genes involved in hormone perception and signalling, as well as genes encoding DNA methyltransferases and enzymes of glutathione metabolism. Pharmacological experiments performed to confirm some of the microarray results showed that Arabidopsis somatic embryogenesis is encouraged by a global hypomethylation of the DNA during the induction phase and by a switch of the glutathione pool towards an oxidized state during the subsequent development phase. Both events occurred in the 35S::BoSTM line, but not in the WT line. Altered expression of Brassica STM also had profound effects on B. napus microspore-derived embryogenesis. The yield of microspore-derived embryos increased in lines overexpressing BnSTM and significantly decreased in antisense lines down-regulating BnSTM.
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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".