ShareThisBy DAVID TEMPLETON
Wednesday, October 11, 2006
The genetic makeup of the poplar or black cottonwood tree is spelled out with 480 million letters arranged in 7.5 million groups. And what it spells is "biofuel."
The U.S. Department of Energy's Joint Genome Institute in Walnut Creek, Calif., has succeeded in sequencing the genome _ the hereditary information encoded in an organism's DNA _ with help from a West Virginia University biologist.
DOE undertook the project to complete the first sequence of a tree genome with the goal of enhancing the production of biofuels. The project involved 108 co-authors from 34 institutions in eight countries.
Stephen DiFazio, a WVU assistant professor of biology, said sequencing of the poplar tree brings insight into the makeup of the broad-leaf hardwood and a better understanding of all trees.
With the sequencing project completed, it's now time to watch the results branch out.
David Gilbert, JGI's manager of public affairs, said the project will help optimize ethanol production from cellulose that makes up the tree cells and lead to domestic growth of trees as an efficient means of producing ethanol.
"Within five years, you will see more emphasis on the plantation approach for development of woody crops for ethanol," Gilbert said.
The genome also will make it possible to genetically engineer trees to produce more cellulose and less lignin _ the glue that holds cellulose together.
Such engineered trees, DiFazio predicted, might look something like "a Dr. Seuss tree" with a short, stout trunk and a green tufts of leaves on top. These fast-growing trees would be grown on plantations, with an effort to keep them apart from wild trees.
"I think this is nothing short of revolutionary," DiFazio said. "We now have the entire complement of genes ready for the taking. People have the tools in hand to look for different functions and to tailor trees for different purposes.
"This is an opportunity for new discoveries in trees," he said. "In fact, we are able to do things now we couldn't do before the gene sequence became available."
Maud Hinchee, chief scientist at Arborgen, a Summerville, S.C., company that does research, development and commercialization of genetic technology to help sustain forests, said the genome project has even wider application.
"The sequencing of the (poplar tree) enables researchers to better understand how to grow trees for all applications including pulp and paper, wood products and the biofuels industry," she said.
Hinchee said wood products grown as "a dedicated energy crop" will help to support DOE's goal to have biofuels represent 30 percent of U.S. transportation fuels by 2030.
The DOE chose the poplar because of its compact genome that's one-sixth the size of the human genome and one-fortieth that of the pine genome, said DiFazio, who served as a staff scientist at DOE's Oak Ridge National Laboratory in Tennessee before taking the position at WVU.
He spent two years working almost full time on the project and is listed as second co-author. He said the project was worth the effort.
"This was the biggest and most complex genome project the DOE has ever tackled," he said. "We learned a lot of lessons that can be applied to other genome projects."
Gilbert said the DOE will turn attention to sequencing the genome of other biofuel plants, including switch grass, sorghum, casaba and soybeans.
Sequencing a genome is tedious work. The DNA is cut into small segments and then entered into sequencing equipment that identifies their makeup, letter by letter. Once the groups of letters are determined, the process becomes one of building "a gigantic puzzle with 7.5 million pieces," DiFazio said.
Those pieces then were assembled to determine the makeup of the tree's 45,000 genes, which in turn were put in proper order to reflect the architecture of the tree's 19 chromosomes.
Now researchers can focus on figuring the function of each of the 45,000 genes.
