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Magdalena Koziol, a former postdoc at Yale University, was the victim of scientific sabotage. Now, she is suing the...
Antiretroviral drugs can protect people from becoming infected by HIV. But so-called pre-exposure prophylaxis, or PrEP...
Two studies show that eating a diet low in protein and high in carbohydrates is linked to a longer, healthier life, and...
Considered an icon of conservation science, researchers at World Wildlife Fund (WWF) headquarters in Washington, D.C.,...
The new atlas, which shows the distribution of important trace metals and other substances, is the first product of...
Early in April, the first of a fleet of environmental monitoring satellites will lift off from Europe's spaceport in...
Since 2000, U.S. government health research agencies have spent almost $1 billion on an effort to churn out thousands...
- 6 March 2014 1:04 pm , Vol. 343 , #6175
- 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.