Genetic and epigenetic changes of rDNA in a synthetic allotetraploid, <i>Aegilops sharonensis</i> × <i>Ae. umbellulata</i>
Bibliographic record
Abstract
The synthetic allotetraploid Aegilops sharonensis x Ae. umbellulata (genomic formula S(sh)U) was used to study inheritance and expression of 45S rDNA during early stages of allopolyploid formation. Using silver staining, we revealed suppression of the NORs (nucleolar organizing regions) from the S(sh) genome in response to polyploidization. Most allopolyploid plants of the S(2)-S(4) generations retained the chromosomal location of 45S rDNA typical for the parental species, except for two S(3) plants in which a deletion of the rDNA locus on one of the homologous 6S(sh) chromosomes was revealed. In addition, we found a decrease in NOR signal intensity on both 6S(sh) chromosomes in a portion of the S(3) and S(4) allopolyploid plants. As Southern hybridization showed, the allopolyploid plants demonstrated additive inheritance of parental rDNA units together with contraction of copy number of some rDNA families inherited from Ae. sharonensis. Also, we identified a new variant of amplified rDNA unit with MspAI1 restriction sites characteristic of Ae. umbellulata. These genetic alterations in the allopolyploid were associated with comparative hypomethylation of the promoter region within the Ae. umbellulata-derived rDNA units. The fast uniparental elimination of rDNA observed in the synthetic allopolyploid agrees well with patterns observed previously in natural wheat allotetraploids.
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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) | 0.001 | 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".