From the Roots Up, Developing Trees for Sustainable Biofuel

By Marcia Goodrich | Published

Poplars, such as these aspens near Michigan Tech, could one day be a sustainable source of biofuel.
Poplars, such as these aspens near Michigan Tech, could one day be a sustainable source of biofuel.

New tree varieties with wonder roots could one day supercharge the biofuel industry.

Scientists at Michigan Technological University aim to develop poplar trees with roots that enable them to thrive in dry, infertile soils. Their work is funded by a three-year, $900,000 grant from the joint USDA and Department of Energy’s Plant Feedstock Genomics for Bioenergy Research Program.

 “Biofuel crops will be grown on marginal lands to avoid competition with food production and curb greenhouse gas emissions,” says Victor Busov, leading project principal investigator. “These plants will have to be pretty robust, and we’re focusing on the roots.”

The poplar is more than a top-quality source of biofuel. It was the first tree to have its entire genome sequenced. Thus, researchers can search among the poplar’s 45,000 genes to find those that regulate its root system—and which genetic variations might result in roots that seek out water and nitrogen more efficiently from the soil. The more efficient the roots, the bigger the trees—and the more biomass to turn into biofuel.

The project has two complementary parts, says Busov, an associate professor in the School of Forest Resources and Environmental Science. In the first, poplars will be grown in dry, nitrogen-poor conditions, and researchers will track how the trees’ genome responds. Then they will map which genetic networks control those responses and modify the key genetic “hubs” that govern those networks in an effort to grow trees with roots better suited to low-nitrogen, dry soils.

In the second experiment, they will generate random mutations in poplars and grow them under similar dry, infertile conditions. Should any of the plants respond well to drought and low nitrogen, the scientists will track which genetic changes are responsible.

Once the scientists identify which genetic modifications produce better roots, they plan to use a variety of approaches, including genetic modifications and traditional breeding techniques, to develop the ideal poplar varieties for biofuel production on marginal lands.

Developing trees that grow big and healthy on poor, droughty soils could help boost biofuel production and reduce dependence on petroleum. Most importantly, it could bring the biofuel industry another step closer to environmental sustainability.

Biofuels may seem like a clean, green alternative to petroleum. But intensive agriculture, for food or for biofuel, can generate a whole array of environmental problems, says Busov.

Typically, 30 percent to 80 percent of nitrogen fertilizers applied to croplands escape to contaminate water, contribute to greenhouse gas emissions, and even increase the incidence of disease vectors like some types of mosquitoes. Irrigation can lead to waterlogging and salinization and divert water from residential and industrial use.

Plus, the energy required to irrigate cropland and to manufacture and apply fertilizer pours even more greenhouse gas into the atmosphere. “Using nitrogen and water more efficiently to produce biomass is simply more sustainable,” says Busov. “If we start on the wrong foot, we are setting ourselves up for disaster in the long run. Sustainable biofuel production is inseparable from efficient nitrogen and water use.”

Co-principal investigators from Michigan Tech on the project are Assistant Professor Hairong Wei and Postdoctoral Researcher Yordan Yordanov, both of the School of Forest Resources and Environmental Science.

Michigan Technological University is a public research university, home to more than 7,000 students from 54 countries. Founded in 1885, the University offers more than 120 undergraduate and graduate degree programs in science and technology, engineering, forestry, business and economics, health professions, humanities, mathematics, and social sciences. Our campus in Michigan’s Upper Peninsula overlooks the Keweenaw Waterway and is just a few miles from Lake Superior.