Ancestral polyploidy and non-linear dosage shifts define the photosynthetic transition in the Heliantheae alliance

A shared paleopolyploid event (WGD-2) ~30 million years ago in the Heliantheae alliance is linked to non-linear genomic dosage shifts that govern the C3-to-C4 photosynthetic transition.

• Why it matters: WGDs are known to shape plant genomes, but how they influence complex carbon-concentrating mechanisms across the C3–C4 spectrum is still unclear.
• What they did: The authors built genome assemblies for 35 Asteraceae species, inferred WGD-2 using Ks and gene-tree reconciliation, then used phylogenetically informed association mapping to test copy-number variation against CO2 compensation point.
• The result: They found 451 MapMan BINs associated with CO2 compensation point variation, with 303 BINs enriched for WGD-2-derived genes (>10%), and effect-size patterns showed threshold-dependent, tipping-point architecture tied to transcription factor module expansions.

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