Conservation and divergence of UVR8 photoreceptor-mediated UV-B signaling in Marchantia polymorpha.
Liang Y, Podolec R, Chappuis R, Defossez E, Glauser G
Plant Signaling
PubMedEvery tomato, rose, and lawn grass you grow has inherited a UV-defense system from ancient plant ancestors — understanding how that system evolved helps scientists engineer more sun-resilient crops and ornamentals for a world with intensifying UV exposure.
Plants have a special protein that acts like a UV-light sensor, warning the plant when harmful ultraviolet radiation is too high so it can protect itself. Researchers studied a primitive plant called a liverwort — a tiny, flat, moss-like plant — and found it has the same basic UV sensor as modern flowering plants, but the helper proteins that control the sensor work differently. This tells us that the core sun-protection tool is ancient and conserved, but plants have been tweaking the volume knob on that system ever since they first crawled onto land hundreds of millions of years ago.
Key Findings
The core UV-B photoreceptor cycle (UVR8) is functionally conserved between liverworts and flowering plants like Arabidopsis, confirming it existed in the last common ancestor of all land plants over 400 million years ago.
The regulatory protein SPA plays a much weaker role in liverworts than in Arabidopsis — liverwort spa mutants showed only a very weak developmental phenotype, unlike the strong effects seen when the equivalent gene is disrupted in Arabidopsis.
Liverwort SPA mutants showed enhanced UV-B tolerance, revealing that MpSPA acts as a negative regulator of UV-B signaling — the opposite functional emphasis compared to its Arabidopsis counterparts.
chevron_right Technical Summary
Scientists discovered that a UV-light sensing system found in ancient liverworts shares a core mechanism with flowering plants like Arabidopsis, but the regulatory proteins that fine-tune the response have evolved differently over 400+ million years. This reveals how plants diversified their defenses against harmful UV-B radiation since first colonizing land.
Abstract Preview
Ultraviolet-B radiation (UV-B) poses a major challenge to all forms of plant life. The liverwort Marchantia (Marchantia polymorpha) serves as a key model organism for studying signaling pathways an...
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Liverworts are a group of non-vascular land plants forming the division Marchantiophyta. They may also be referred to as hepatics. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information. The division name ...