Genetically engineered trees for biofuel production
RESEARCHERS HAVE genetically engineered poplar trees with lignin that breaks down more easily, opening the door to cheaper biofuels and wood pulp that require only a fraction of the energy and chemicals to produce, according to a piece in The Vancouver Sun
By inserting a piece of code isolated from a Chinese herb into the DNA of a poplar tree, scientists at the University of British Columbia, Michigan State and University of Wisconsin-Madison have produced a tree designed for easy deconstruction.
The code alters the chemistry of some of the bonds that hold together lignin, the organic polymer glue that makes trees tough and rigid and protects the energy-rich cellulose within cells.
The genetically engineered poplars are every bit as strong as normal poplars while they are living, but when processed the lignin “unzips” where the altered bonds occur in the polymer chain.
Removing naturally occurring lignin for the production of bioethanol and paper products requires caustic chemicals and high heat, about 170 C for several hours, according to an online article in the journal Science. Zip-lignin falls apart in a mild alkaline solution at just 100 C.
The group’s initial efforts to reduce lignin content resulted in trees that were stunted, weak and susceptible to pests. The key was not less lignin, but simply to alter the lignin slightly so it would come apart easily when prompted.
Genomics — the analysis of the complete DNA code of organisms — makes it possible to identify plants that have certain desirable characteristics and use that information to speed conventional selective breeding, but also to identify specific pieces of genetic code that can be altered, suppressed or augmented to produce plants better suited to human needs.
GE poplar could be grown on plantations on agricultural land unsuited to food crops and provide a source of biofuel that does not compete with food crops.
To prevent “gene flow” to wild poplars, the GE trees could be made sterile or harvested before they attain reproductive maturity.