Cell
Volume 181, Issue 5, 28 May 2020, Pages 1097-1111.e12
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Article
The Penium margaritaceum Genome: Hallmarks of the Origins of Land Plants

https://doi.org/10.1016/j.cell.2020.04.019Get rights and content
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Highlights

  • The genome and responses of a charophyte alga uncover terrestrialization mechanisms

  • Paradoxical presence of protective UV-absorbing flavonoid pigments

  • Evolutionary origins of plant hydrophobic polymer classes that limit water loss

  • Expanded repertoire of genes for polysaccharide cell wall biosynthesis and remodeling

Summary

The evolutionary features and molecular innovations that enabled plants to first colonize land are not well understood. Here, insights are provided through our report of the genome sequence of the unicellular alga Penium margaritaceum, a member of the Zygnematophyceae, the sister lineage to land plants. The genome has a high proportion of repeat sequences that are associated with massive segmental gene duplications, likely facilitating neofunctionalization. Compared with representatives of earlier diverging algal lineages, P. margaritaceum has expanded repertoires of gene families, signaling networks, and adaptive responses that highlight the evolutionary trajectory toward terrestrialization. These encompass a broad range of physiological processes and protective cellular features, such as flavonoid compounds and large families of modifying enzymes involved in cell wall biosynthesis, assembly, and remodeling. Transcriptome profiling further elucidated adaptations, responses, and selective pressures associated with the semi-terrestrial ecosystems of P. margaritaceum, where a simple body plan would be an advantage.

Keywords

Zygnematophyceae
Penium
unicellular algae
plant evolution
terrestrial abiotic stresses
phytohormone
cell wall
flavonoids
transcriptional regulation
gene family evolution

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These authors contributed equally

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