Biochemistry

Abstract

CS-21-5 - Early plant evolution: stress signalling circuits in the algal ancestors of land plants

Tuesday, July 17
9:53 AM - 10:13 AM

All land plants evolved from a streptophyte algal progenitor in a monophyletic event. Zygnematophyceae are, of all extant streptophyte algae, those that are most closely related to the algal land plant progenitor. One of the major questions revolving around the algal ancestors of land plants is what features enabled only this particular organism to conquer land on a global scale. A prime candidate feature is the ability to ward off terrestrial stressors, including drought, high light, and rapid chilling stress. Using comparative transcriptomics, we investigated streptophyte algal stress response signaling towards the latter two stressors. For this, we analyzed one representative of each of the six major classes of streptophyte algae, including the Zygnematophyceae Zygnema. As in land plants, high light and cold stress impacted plastid biology as indicated by differential gene expression of a variety of plastid and photosynthesis-associated genes. Zygnema further invested the highest transcript budget into plastid biology-associated gene expression. This suggests that the plastid of streptophyte algae might be an equally important hub in stress-response as in land plants. While our data pinpoint the presence of many stress signaling circuits known from land plants in various streptophyte algae, Zygnema particularly stands out: only Zygnema has the full genetic repertoire for sensing the stress phytohormone abscisic acid and mounting its canonical signaling pathway. This not only underscores the phylogenetic position of the Zygnematophyceae but is also directly relevant for the inferences of the algal land plant progenitors stress signaling capacities. From these data, we infer that embryophytic stress signaling circuits were among those features that helped the algal land plant ancestor during terrestrialization.


 

Co-Authors

Bruce Curtis – Dalhousie University; Sven Gould – Heinrich-Heine-Universität Düsseldorf; John Archibald – Dalhousie University

Jan de Vries

Postdoctoral Fellow (DFG Research Fellow)
Dalhousie University

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CS-21-5 - Early plant evolution: stress signalling circuits in the algal ancestors of land plants



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