A study of more than 100 species and 2,000 genes has rewritten the origin story of land plants. Published in PLOS Biology in November 2026, the phylogenomic research reveals that the Zygnematophyceae—the closest living algal relatives of land plants—evolved multicellular growth multiple times independently. The transition to complex body plans was not a single, linear event, but a repeated emergence from simpler forms.
Algae Developed Multicellularity Through Repeated Evolution
The international research team generated 43 new transcriptomes to supplement existing public data. This expanded dataset allowed the team to identify a deep genetic structure within this streptophyte algal class. Using 104 transcriptomes across 2,243 loci, the study mapped how these organisms diverged.
Bioengineer reports that the analysis traces evolutionary divergence between the unicellular Desmidiales and the Spirogyrales. Most Spirogyrales emerged following a deep split from these unicellular groups. This genetic divergence enabled multicellularity and specialized traits, such as unique methods for cell and plastid division.
Genes for Land Plants Predate Terrestrial Life
The genetic foundation for plant life was established long before the first plants colonized land. Cäcilia Kunz of the University of Göttingen noted that these algae contain genes belonging to what researchers call the land plant heritage.
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“They show that some of the molecular components associated with important plant functions have much deeper evolutionary histories than the land plants themselves. At the same time, their distribution across algal lineages shows that this evolutionary toolkit was dynamic,” Cäcilia Kunz, University of Göttingen
The biological toolkit used by land plants was not invented during the transition to land. Instead, various algal lineages experimented with these tools over hundreds of millions of years.
Genomes Reveal Complexity Behind Simple Forms
Zygnematophyceae include single-celled organisms and filamentous algae like Spirogyra that appear straightforward. However, their genomic data reveals a more intricate history. Dr. Maaike Bierenbroodspot conducted the research for her Ph.D. at Göttingen University.
“Many zygnematophytes look deceptively simple, but their genomes reveal a remarkably deep and complex evolutionary history and diversity. We can begin to see evolutionary events that remain invisible when we study only a handful of model species,” Dr. Maaike Bierenbroodspot
Evolution did not follow a straight line from single cells to complex plants. Different lineages tested various molecular solutions and body plans throughout their history, according to Professor Jan de Vries of the University of Göttingen.
Scientific Frontline reports that de Vries believes understanding this diversity is essential. This knowledge helps reconstruct the biology of the specific algal ancestors that eventually gave rise to land plants.
Researchers Map Ancestral Algal Lineages
This study provides a framework for understanding how ancestral algae developed innovations for the conquest of land. The current dataset covers a portion of the class, but it represents only a fraction of the more than 4,000 described Zygnematophyceae species.
Our study gives us a much better map of the evolutionary landscape surrounding the origin of land plants,