The Genomic Basis of the Tristylous Floral Polymorphism: Evidence for a Role of Gene Duplications in a Region of Restricted Recombination
Bibliographic record
Abstract
Tristyly is an angiosperm sexual polymorphism characterized by three flower morphs maintained in populations by negative frequency-dependent selection resulting from disassortative mating among morphs. The floral morphs possess reciprocal stigma and anther heights controlled by two epistatically interacting diallelic loci (S and M). Although considerable progress has been made on determining the genetic architecture and genes governing the related heterostylous polymorphism distyly, our understanding of these aspects of the genetic basis of tristyly has not been examined. Here, we address this knowledge gap by investigating the genomic basis of tristyly in Eichhornia paniculata (Pontederiaceae), an annual bee-pollinated herb native to the Neotropics, primarily N.E. Brazil. With chromosome-level genome assemblies of E. paniculata, we dentified the S- and M-loci on either side of a large region of low recombination on the same chromosome. The S-locus consisted of two divergent haplotypes: the S-haplotype (2.51 Mb) with three S-haplotype-specific genes and the s-haplotype (596 kb) with five s-haplotype-specific genes. Two of the S-haplotype-specific genes, LAZY1-S and HRGP-S, were specifically expressed in styles and stamens, respectively, making them candidate tristyly genes and providing evidence for this locus functioning as a hemizygous supergene. The M-locus contained one gene (LAZY1-M), homologous to LAZY1-S, present in the M-haplotype but absent from the m-haplotype. Estimates of gene ages and phylogenetic reconstruction were consistent with the theoretical prediction that the S-locus evolved before the M-locus. Evidence for reuse of the same gene highlights the potential role of gene duplication in the evolution of epistatic multilocus polymorphisms.
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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 | 0.000 |
| 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".