"The core mechanism activating the UVR8 photoreceptor is conserved between Marchantia and flowering plants."
Ancient Sunscreen: How Early Plants Learned to Block UV-B
An international team led by the University of Geneva (UNIGE) has published new findings on the evolution of plant UV-B protection mechanisms. The study, published in Plant Physiology, focuses on the liverwort Marchantia polymorpha—a species similar to early land plants from over 400 million years ago.
Key Findings
The core mechanism activating the UVR8 photoreceptor is conserved between Marchantia and flowering plants. This suggests the basic "switch" for UV-B protection is remarkably ancient.
However, the regulatory "brakes" have evolved differently:
- The SPA protein in Marchantia acts as a brake on UV-B protective responses, whereas in Arabidopsis it works with COP1 to regulate growth.
- Marchantia mutants lacking SPA show increased UV-B tolerance, confirming its role as a suppressor in this species.
Background
Plants need sunlight for photosynthesis, but must protect themselves against harmful UV-B radiation. The UVR8 photoreceptor triggers molecular cascades that upregulate protective genes. How this signalling pathway evolved was not well understood before this study.
Implications
The results suggest that the basic components of the UV-B response system were present early in plant evolution, but their regulation has changed over time.
Understanding how plants adapt to light stress may help predict responses to changing light conditions due to climate change.