A newly discovered gene may be the key to producing fuel ethanol more efficiently from trees, and the University of Florida researchers who identified it have received a prestigious federal grant to investigate further.
The gene, which helps regulate wood growth and the composition of wood fiber, could also lead to improved tree varieties for pulp and paper.
Matias Kirst and Gary Peter, plant geneticists with UF’s Institute of Food and Agricultural Sciences, lead the team. They received one of seven 2009 Plant Feedstock Genomics for Bioenergy grants-a program from the U.S. Department of Agriculture’s Cooperative State Research, Education and Extension Service, and the U.S. Department of Energy’s Office of Science.
The grants, totaling $6.32 million, were announced in late July. The UF team’s three-year, $643,000 grant will fund research on how the gene helps regulate cell wall chemistry and structure. The scientists will also investigate where and when its effects occur.
Eventually, they will create genetically engineered trees that over-express or under-express the gene, to study resulting changes in wood composition and biomass growth.
“We focus on understanding very fundamental biological mechanisms that may be critical for the productivity of tree species and the quality of wood products,” said Kirst, with UF’s School of Forest Resources and Conservation. “The gene cpg13 appears to play a critical role in these traits.”
Cpg13, which stands for Carbon Partitioning and Growth on chromosome 13, was identified by one of Kirst’s graduate students, Evandro Novaes. The gene was isolated in poplar trees, but may exist in other species.
It appears cpg13 controls how much of the carbon taken up by a poplar tree is used to make cellulose and lignin, two major building blocks of plant cell walls.
Cellulose is a complex carbohydrate, which can be broken down into glucose and fermented to produce biofuels. Wood with high cellulose and low lignin content is better suited for biofuels such as ethanol, because it should convert more efficiently and with greater yields.
High cellulose content is also a desirable trait for producing pulp and paper.
What’s more, there’s apparently a link between high cellulose content and fast tree growth, Kirst said. It may be possible to engineer trees that not only produce large amounts of wood quickly, but also have the ideal properties for biofuel, as well as pulp and paper production.
However, there is a potential benefit to trees with high lignin content. Plant materials rich in lignin degrade slower than those with more cellulose. It may be possible to engineer high-lignin trees that could be used to store carbon and reduce greenhouse gases that cause global climate change.
Another possibility, Kirst said, would be to develop trees with high cellulose content in stems and high lignin content in roots, offering the best solution for mitigating greenhouse gases.
The team also published a paper in the June issue of New Phytologist demonstrating that nitrogen fertilizer has a significant effect on genes that regulate growth and wood composition in poplar trees.
One expert likened the UF paper to studies showing that the interplay between nutrition and genetics has consequences for human health.
Malcolm Campbell, a professor with the University of Toronto’s department of cell and systems biology, said scientists have often viewed improvement of tree crops as a matter of genetic selection, but the UF team’s work demonstrates that much can be changed in the wood composition by silvicultural practices.
“The way this will shape forestry for the future is quite cutting-edge,” Campbell said.