Formation and centromere inactivation of fusion chromosomes in two allotetraploid species from the <i>Saccharum</i> complex
Bibliographic record
Abstract
Chromosome fusion can cause a change in the basic chromosome number of a species, thus imposing a major impact on speciation. However, there are few studies on the structure and evolution of fusion chromosomes in plants. Erianthus rockii and Narenga porphyrocoma are allotetraploid species within the Saccharum complex. Both species possess five distinct fusion chromosomes, each resulting from the fusion of two ancestral chromosomes. We developed a high-resolution oligonucleotide (oligo)-based painting technique and constructed a detailed cytogenetic map for each of the 10 fusion chromosomes, enabling visualization of the breakpoints and fusion events of their ancestral chromosomes. We observed several common features associated with the 10 fusion chromosomes. The breakpoints of these fusion chromosomes were consistently located in the proximal regions near the centromeres of the ancestral chromosomes. Each fusion event was accompanied by the inactivation of one of the two ancestral centromeres, along with the loss of the associated centromeric repeats in the inactivated centromere. We conclude that the 10 fusion chromosomes likely originated through different mechanisms, including nested chromosome fusion, end-to-end fusion, and centromere misdivision followed by rejoining of the resulting fragments.
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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 | 0.001 | 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".