|Poplar Trees: Getting to the Roots of Carbon Storage|
By Kate Dalke
July 25, 2003
Trees may literally hold part of the answer to the problem of global warming. They store carbon in their branches, leaves, and roots, thereby reducing carbon dioxide in the atmosphere.
Scientists are trying to clean up the air by engineering trees that would shuttle and store more carbon belowground in their roots and the soil.
They are searching for genes and hormones in the poplar tree that could be modified to improve how these trees transport carbon to their roots. The research is part of the U.S. Department of Energy’s Genomes to Life program.
“Carbon management issues are overwhelmingly large, but the poplar tree could play a significant role in the final solution,” says Gerald Tuskan of DOE’s Oak Ridge National Laboratory in Tennessee, who leads the research.
All trees absorb carbon dioxide through photosynthesis and store carbon in their cell walls aboveground in stems, leaves, and branches and belowground in their roots. Carbon stored aboveground is more rapidly released back into the atmosphere than is carbon stored underground.
Tuskan and his colleagues hope to increase the amount of carbon stored underground by modifying some of these naturally occurring processes in the poplar tree.
The genome sequence of the poplar tree, expected by the end of this year, could accelerate scientists’ search for genes and pathways involved in moving carbon to the tree’s roots.
The poplar’s genome will be the first tree genome sequenced. DOE’s Joint Genome Institute in Walnut Creek, California, completed a preliminary draft of the genome ahead of its 18-month schedule, and is finishing the sequencing this fall.
Down the road, Tuskan envisions large-scale tree farms that would capture and store carbon underground. One option is to plant these trees on millions of excess and empty acres of agricultural land in the United States.
The poplar tree is a natural choice for these studies. It grows fast—up to 4 meters annually—and matures in about six years. Poplar trees can be used as pulp for paper and as a source of ethanol for fuel.
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