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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
- About Us
Too Much of a Good Thing
21 January 2005 (All day)
Plants are supposed to crave sunlight, but too much sunlight can create potentially deadly free radicals. Now researchers have identified a mechanism plants use to protect themselves. The discovery could aid the development of genetically modified crops that adapt to different light conditions.
Plants harvest energy from the sun with the help of chlorophyll and carotenoid, two photon-capturing molecules. But if the plants are exposed to too much sun, these molecules absorb more energy than they can handle and generate reactive species of oxygen that can destroy the plant. Researchers have known for more than 20 years that plants have a way to protect themselves against this damage, but the actual mechanism has remained a mystery.
It turns out plants use a unique safety valve, according to research published this week in Science. Utilizing instruments that were able to record chemical reactions lasting one millionth of a billionth of a second, a team of researchers from the University of California at Berkeley and the Lawrence Berkeley National Laboratory in Berkeley, California, followed the path of absorbed solar energy in spinach leaves and Arabadopsis. The researchers found that excessive sunlight triggers the formation of zeaxanthin, a member of the carotenoid family. The molecule transfers an electron to chlorophyll, rendering it incapable of generating reactive oxygen. The positively charged zeaxanthin then combines with the negatively charged chlorophyll in a reaction that disperses away excess energy as heat.
Team member Graham Fleming, a biochemist affiliated with both Berkeley and the Lawrence Berkeley National Laboratory, says that the zeaxanthin defense mechanism is so sensitive, it even turns itself off when clouds pass overhead.
The new report is an important study that offers the first clear-cut evidence of the mechanism plants use to protect themselves, says Yale University biophysical chemist Gary Brudvig. Robert Blankenship, a biochemist at Arizona State University, adds that the findings could aid the development of artificial photosynthesis systems for efficiently harnessing solar energy, or high yielding genetically modified crops that can be fine-tuned to different light environments.