Wood is strong, abundant, and cheap. But when it comes to the prospect of turning trees and agricultural waste into an energy source for cars and trucks, wood gets in the way. Now scientists say they have found a possible solution to this difficulty, one that could dramatically reduce the cost of tomorrow's fuels.

The problem with wood is a component in its cell walls known as lignin, which confers rigidity. Engineers must first remove the lignin to get to the sugar-rich cellulose in plants, which they ferment into alcohol-based fuel. Researchers have been looking for ways to reduce the amount of lignin in trees and plants without harming their ability to grow.

It is no easy task. Lignin isn't like other long-chain biological molecules. DNA and RNA, for example, are copied directly from molecular templates. Lignin's structure, by contrast, is more haphazard.