Ultraviolet protection molecule in plants yields its secrets to ressearchers

Lying around in the sun all day is hazardous not just for humans but also for plants, which have no means of escape. Ultraviolet (UV) radiation from the sun can damage proteins and DNA inside cells, leading to poor growth and even death (as well as carcinogenesis in humans).

But plants have evolved some powerful adaptive defenses, including a complex array of protective responses orchestrated by a UV-sensing protein molecule known as UVR8. Now, scientists from The Scripps Research Institute and the University of Glasgow have put together a detailed picture of UVR8's structure and inner workings.

''It's an ancient molecule that seems to play a fundamental role in plants,'' said Scripps research professor Elizabeth Getzoff. ''Knowing how it works helps us to understand better how plant growth varies with changes in sunlight, for example due to climate shifts; it's also important that we understand its basic light-switch mechanism.''

Getzoff was a principal investigator for the study, which is reported 9 February in the journal Science's early online edition, Science Express.

Sunscreen for plants
Researchers first found evidence of UVR8's protective function in 2002, when they knocked out its gene in the wild mustard plant Arabidopsis, the standard experimental model for plant biologists. The mutant plants grew poorly when exposed to UV ''B'' wavelength radiation - the range most responsible for tanning and burning of human skin.

When UVR8 is present in Arabidopsis, it can sense UV-B light and switch on a broad protective response involving more than 100 Arabidopsis genes. ''These are genes for DNA-repair enzymes and other protective proteins,'' said Getzoff. ''It's the plant equivalent of putting on sunscreen.''