Scientists devise world’s first genetic ‘blueprint’ for trees

September 15, 2006
Vancouver Sun
By Nicholas Read
CanWest News Service

On to the next step — what is the function of the 45,000 genes?

VANCOUVER — Researchers from the University of British Columbia and Vancouver’s Genome Sciences Centre have helped draw the world’s first genetic blueprint for a tree, a revelation that could lead to important discoveries about climate change, alternative fuels and wood production.

In other words, they are first scientists ever to identify all the genes — in this case, more than 45,000 of them — that dictate the form and function of a tree. Now their challenge is to figure out what each of those 45,000 genes does.

Their findings, which are published in the latest edition of Science magazine, refer specifically to the black cottonwood, a broad-leafed and resinous subspecies of balsam poplar that is found in B.C. forests west of the Rocky Mountains.

“In tree biology, this is equivalent to sequencing the first human genome,” said UBC forest scientist and botanist Joerg Bohlmann, who co-authored the paper with fellow UBC botanist Carl Douglas.

It is also only the third time a plant has been sequenced genetically. Arabidopsis, a small flowering plant of the mustard family, was sequenced in 2000, and the genome of rice was sequenced in 2004.

Using the blueprint they’ve produced, Bohlmann and other researchers now can begin to figure out which gene in the cottonwood does what. And that could have important implications for forests of the future.

For example, there may be a gene or set of genes in the cottonwood that enables it to sequester greenhouse gases effectively. Or maybe there is a gene or set of genes that dictates the efficient production of cellulose, a substance used in the production of pulp and a potential source of biofuels.

If scientists could identify these genes in the black cottonwood, Bohlmann said, they might be able to recognize them in other trees too.

And if they could do that, they also might be able to identify the types of trees that are best at sequestering greenhouse gases and/or producing cellulose.

Other trees, by contrast, may turn out to be more efficient at producing lignin, an integral component of wood. Or maybe they will contain genes that help them live longer or survive mountain pine beetles better.

By knowing and understanding all these genetic characteristics, Bohlmann says, forest scientists one day may be able to help foresters create trees tailored to meet specific industrial or environmental needs.

One such tree likely would be a poplar that could be used to produce ethanol. Currently, ethanol is more expensive and difficult to produce from wood than it is from corn or sugarcane.

“At this time, I would hope that within the next 10 years, based on this blueprint and based on comparisons to other plants, we will hopefully be able to assign functions to most of these genes,” he said.

Assigning functions to different genes often begins with identifying where in the tree they exist. For example, some genes may only occur in the tree’s leaves or bark or roots. If that’s the case, it’s likely these genes will have something to do with the construction, function or regulation of leaves, bark or roots.

“If I find a gene to be present exclusively in a root tip, but not in the flowers or stems, this gene most likely is involved in a root-specific process,” Bohlmann said.

He and his colleagues chose to study the black cottonwood because compared to other trees — the pine or Douglas fir, for instance — it has a small genome. Big enough at 45,000 genes to make mapping it a colossal achievement, but small enough for researchers to tackle at a first go.

The $10-million, four-year project was led by the U.S. Department of Energy’s Genome Institute in California and the Oak Ridge National Laboratory in Tennessee, and involved 34 institutions from around the world.

In addition to Bohlmann and Douglas, the lead B.C. scientists were Brian Ellis and Kermit Ritland from UBC and Marco Marra, Steven Jones, Jaquie Schien and Rob Holt from the Genome Sciences Centre.