Mimicking Plant Evolution Proves Fruitful

By mimicking plant evolution, a team of researchers has improved upon nature's design to build a leafy energy-producing powerhouse - or at least a virtual one on a supercomputer.

Efforts to improve crop yields without resorting to more nitrogen-based fertilizer and a growing interest in plant-based biofuels have combined to make the energy-amassing process of photosynthesis a hot research topic. A big challenge, according to University of Illinois at Urbana-Champaign crop sciences professor Steve Long, is ensuring that enough energy can be produced to yield both food and fuel.

In a study published within the journal Plant Physiology, Long and colleagues have suggested a way forward for both aims by using a supercomputer to design a photosynthetic pathway that is 76 percent more efficient than anything found within natural greenery.

In photosynthesis, all green plants, algae and some microbes use sunlight to convert water and carbon dioxide into oxygen and energy stored as carbohydrates. Some scientists view the pathway as the most important biological process on Earth because it supplies most building materials and all food (either directly or through plant-eating animals). Photosynthesis also counteracts the effect of burning fossil fuels by consuming carbon dioxide.

The carbon-converting prowess of photosynthesis, in fact, is why planting more trees is commonly cited as a way to help mitigate global warming. Understanding the underlying mechanisms of the pathway could help increase wheat and other crop yields, make better use of existing solar energy, and augment the production of corn, switchgrass and other plant-derived biofuels as oil alternatives.

Photosynthesis is inefficient

Over the past half-century, researchers have been able to describe the dozens of enzymes and reactions involved in photosynthesis. "And one of things that's known about this process is that it's not very efficient," Long said. If green plants aren't optimizing their investment, he thought, might scientists be able to tweak the process to essentially build a better plant?

On a supercomputer, at least, it's no contest.

Robert Blankenship, a professor of biology and chemistry at Washington University in St. Louis, said he was surprised by the "dramatic" increase in efficiency obtained by Long's group. "If you could increase carbon fixation by 76 percent (in the real world), that would be a huge deal," said Blankenship, who wasn't involved with the study.

At its core, the study consisted of a series of linked differential equations that essentially mimicked each reaction within photosynthesis. The computer-assisted linkup, Blankenship said, allowed the scientists to reconstruct the complicated pathway on the computer and tinker with it in way that would be very difficult to do with real plants. Long's team determined the starting amounts of each protein from prior studies, and after linking up the equations, kept testing and tweaking the model until it successfully predicted the outcome of experiments performed on living leaves.

"For reactions strung together in a fairly complicated way, it's very difficult to go in there and say, 'Maybe we should change this one or that one,' " Long said. ...

•	Mimicking plant evolution proves fruitful MSNBC.com, Thursday, Jan. 10, 2008 Byline: Bryn Nelson