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12 December 2013 1:00 pm ,
Vol. 342 ,
The iconic 125-year-old Lick Observatory on Mount Hamilton near San Jose, California, is facing the threat of closure...
Recent results from the Curiosity Mars rover have helped scientists formulate a plan for the next phase of its mission...
A new, remarkably powerful drug that cripples the hepatitis C virus (HCV) came to market last week, but it sells for $...
In pretoothbrush populations, gumlines would often be marred by a thick, visible crust of calcium phosphate, food...
Evolutionary biologists have long studied how the Mexican tetra, a drab fish that lives in rivers and creeks but has...
Victorian astronomers spent countless hours laboriously charting the positions of stars in the sky. Such sky mapping,...
In an ambitious project to study 1000 years of sickness and health, researchers are excavating the graveyard of the now...
Stefan Behnisch has won awards for designing science labs and other buildings that are smart, sustainable, and...
- 12 December 2013 1:00 pm , Vol. 342 , #6164
- 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.