Divergent responses in desiccation experiments in two ecophysiologically different Zygnematophyceae
Tim P Rieseberg1, Armin Dadras1, Luisa I N Bergschmidt1
1Department of Applied Bioinformatics, University of Goettingen, Institute of Microbiology and Genetics, Goettingen, Germany.
Physiologia Plantarum
|December 26, 2023
Summary
Two algae species, Zygnema and Mesotaenium, reveal conserved drought tolerance mechanisms shared with land plants. Their transcriptomic responses highlight adaptations in signaling, plastid biology, and amino acid pathways during desiccation.
Area of Science:
- Plant biology
- Evolutionary biology
- Physiology
Background:
- Water scarcity and desiccation are major environmental stressors for land plants.
- Drought tolerance strategies, avoidance and tolerance, evolved early in land plant lineages.
- The Zygnematophyceae, close relatives of land plants, offer insights into the evolution of terrestrial life.
Purpose of the Study:
- To investigate drought tolerance mechanisms in Zygnematophyceae, the closest algal relatives to land plants.
- To compare the responses of two Zygnematophyceae species with differing habitats and drought resilience to severe desiccation.
- To identify conserved molecular pathways between Zygnematophyceae and land plants related to desiccation tolerance.
Main Methods:
- Laboratory-based desiccation experiments on Zygnema circumcarinatum and Mesotaenium endlicherianum.
- Assessment of morphological, photophysiological, and transcriptomic responses during and after desiccation.
- Comparative analysis of gene expression patterns to identify conserved and divergent responses.
Main Results:
- Both species exhibited conserved gene expression patterns related to calcium signaling, plastid biology, cell envelopes, and amino acid metabolism.
- Zygnema showed a readjustment in photobiology, while Mesotaenium experienced stress beyond a critical threshold.
- Differential gene expression revealed conserved responses between Zygnematophyceae and land plants despite ecophysiological divergence.
Conclusions:
- Drought tolerance mechanisms in Zygnematophyceae share conserved pathways with land plants, providing insights into land colonization.
- Species-specific differences in response, particularly in photobiology, contribute to varying drought resilience.
- Understanding these algal systems is crucial for comprehending the evolution of plant terrestrial adaptation.
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