Daily Archives: February 18, 2014

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A foreign fungus nearly wiped out North America's once vast chestnut forests. Genetic engineering can revive them

In 1876 Samuel B. Parsons received a shipment of chestnut seeds from Japan and decided to grow and sell the trees to orchards. Unbeknownst to him, his shipment likely harbored a stowaway that caused one of the greatest ecological disasters ever to befall eastern North America. The trees probably concealed spores of a pathogenic fungus, Cryphonectria parasitica, to which Asian chestnut treesbut not their American cousinshad evolved resistance. C. parasitica effectively strangles a susceptible tree to death by forming cankerssunken areas of dead plant tissuein its bark that encircle the trunk and cut off the flow of water and nutrients between the roots and leaves. Within 50 years this one fungus killed more than three billion American chestnut trees.

Before the early 1900s the American chestnut constituted about 25 percent of hardwood trees within its range in the eastern deciduous forests of the U.S. and a sliver of Canadadeciduous forests being those composed mostly of trees that shed their leaves in the autumn. Today only a handful of fully grown chestnuts remain, along with millions of root stumps. Now and then these living stumps manage to send up a few nubile shoots that may survive for 10 years or longer. But the trees rarely live long enough to produce seeds because the fungus almost always beats them back down again.

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The American Chestnut's Genetic Rebirth

WSU staff scientist Barri Herman, who oversees the field trials, holds a tray of genetically engineered poplar cuttings, Jan. 13, 2014. (Greg Gilbert/Seattle Times/MCT)

Under USDA regulations, every genetically engineered tree is tagged and its GPS coordinates noted, as seen, Jan. 13, 2014, in Washington State. (Greg Gilbert/Seattle Times/MCT)

SEATTLE _ Sniff the air around Norman Lewis' experimental poplars, and you won't pick up the scent of roses.

But inside the saplings' leaves and stems, cells are hard at work producing the chemical called 2-phenylethanol _ which by any other name would smell as sweet.

Sweeter still is the fact that perfume and cosmetics companies will pay as much as $30 an ounce for the compound that gives roses their characteristic aroma. Because what Lewis and his colleagues at Washington State University are really chasing is the smell of money.

Born out of the frustrating quest to wring biofuels from woody plants, the WSU project takes a different tack. Instead of grinding up trees to produce commercial quantities of so-called cellulosic ethanol, their goal is to turn poplars into living factories that churn out modest levels of chemicals with premium price tags.

The potential market for specialty chemicals _ many of which are now synthesized from petroleum _ is big, said Lewis, director of WSU's Institute of Biological Chemistry. He's already patented some of the technology, which relies on genetic engineering, and created a spinoff company called Elasid.

In the longer term, the profits from high-end products could boost the struggling biofuel industry by helping companies survive what's called the "valley of death" _ the point where firms need to scale up production, but money is hard to come by.

The ideal operation would combine the two product lines, extracting valuable chemicals and using the waste for biofuel. But that's a long way off, Lewis said.

"Biofuels don't provide a compelling economic case at this point in time," he said. "We've been trying for many decades to understand how plants make these special chemicals that can be used in flavorings, fuels and medicinals, and that seemed like the obvious first place to target."

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Rose scent in poplar trees? University turns to genetic engineering