Reticulate allopolyploidy and subsequent dysploidy drive evolution and diversification in the cotton family

Area of Science:

• Plant evolutionary genomics
• Angiosperm paleopolyploidy
• Malvaceae family evolution

Background:

• Polyploidy and post-polyploid diploidization (PPD) are significant evolutionary mechanisms in plants, but their precise roles are debated.
• The Malvaceae family offers a valuable model system to investigate the evolutionary impact of polyploidy and PPD.

Purpose of the Study:

• To reconstruct the paleopolyploidy history within the Malvaceae family.
• To investigate the relationship between post-polyploid diploidization dynamics and taxonomic richness.
• To test the hypothesis that polyploidy enhances survival and PPD drives evolutionary success.

Main Methods:

• Analysis of 11 high-quality chromosome-scale genomes from Malvaceae subfamilies.
• Sequencing of near telomere-to-telomere assemblies for four Malvaceae subfamilies.
• Reconstruction of paleopolyploidy events and dysploidy rates.

Main Results:

• A complex reticulate paleoallopolyploidy history was identified early in the Malvadendrina clade diversification.
• Ancient allotetraploidization (Mal-β) and allodecaploidization (Mal-α) events occurred around the Cretaceous-Paleogene boundary.
• A strong correlation was found between dysploidy rate and taxonomic richness in paleopolyploid subfamilies (R² ≥ 0.90, P < 1e-4).

Conclusions:

• The study supports the "polyploidy for survival and PPD for success" hypothesis.
• Polyploidy-dysploidy waves played a critical role in shaping the biodiversity of the Malvaceae.
• This research provides a comprehensive evolutionary history of the Malvaceae, highlighting the importance of genome duplication and reduction events.