Researchers design trees easier to break down for paper production
The study, published in the U.S. journal Science, is focused on a polymer found in wood known as lignin, which represents "one of the largest impediments for the pulp and paper industry as well as the emerging biofuel industry," study author Shawn Mansfield, a professor of Wood Science at the University of British Columbia, said.
Lignin makes up a substantial portion of the cell wall of most plants and keeps them upright, but it also makes them very hard to break down. Currently, lignin must be removed for the production of pulp, paper and biofuel, a process that requires significant chemicals and energy and causes undesirable waste.
Researchers had previously tried to tackle this problem by reducing the quantity of lignin in trees by suppressing genes, which often resulted in trees that are stunted in growth or were susceptible to wind, snow, pests and pathogens.
In the new study, the researchers found a gene from a herb DangGui or Chinese angelica and successfully put it into poplar trees, a fast-growing crop widely planted throughout the United States and Canada.
The resulting poplar trees showed no difference in growth habit under greenhouse conditions, but the lignin from those plants showed improved degradation properties, the researchers said.
They determined that the gene modified the poplars' natural lignin to make it easier to break down without adversely affecting the trees' strength.
"We're designing trees to be processed with less energy and fewer chemicals, and ultimately recovering more wood carbohydrate than is currently possible," said Mansfield. "It is truly a unique achievement to design trees for deconstruction while maintaining their growth potential and strength."
The genetic modification strategy employed in this study could also be used on other plants like grasses to be used as a new kind of fuel to replace petroleum, the researchers said.
Genetic modification is a contentious issue, but there are ways to ensure that the genes do not spread to the forest, they said.
These techniques include growing crops away from native stands so cross-pollination isn't possible; introducing genes to make both the male and female trees or plants sterile; and harvesting trees before they reach reproductive maturity.
In the future, genetically modified trees could be planted like an agricultural crop, not in our native forests, they said.
"We're a petroleum reliant society," said Mansfield. "We rely on the same resource for everything from smartphones to gasoline. We need to diversify and take the pressure off of fossil fuels. Trees and plants have enormous potential to contribute carbon to our society." ■