A researcher at The University of Texas at Austin will receive two grants totaling $15 million to study switchgrass (Panicum virgatum), with a focus on how it can become a sustainable source of bioenergy.
Tom Juenger, a professor of integrative biology, will lead scientists from multiple institutions—including federal agencies, universities and the HudsonAlpha Institute for Biotechnology—on two projects researching switchgrass. A five-year grant from the Department of Energy’s Office of Biological and Environmental Research will provide $11 million for the university and $4 million for partner institutions. Additionally, the National Science Foundation (NSF) awarded a four-year grant of $4 million to Juenger and his team. Both grants begin this fall.
On the larger of the two projects, researchers will collect and sequence the genes of hundreds of switchgrass samples to study how genes and a host of environmental factors—including the soil, bacterial communities that live on the plant and in the soil, weather and the size and growth rate of each plant—affect the plant and its potential as a biofuel. Understanding how different factors affect one another ultimately will provide insights into basic plant biology and allow scientists to identify ways to improve switchgrass as an alternative energy source.
Switchgrass is found in the tallgrass prairies across North America and can thrive in soils unsuitable for other crops, making it useful not only for livestock grazing and to prevent soil erosion, but as a potential biofuel.
Juenger and fellow researchers have examined biofuel applications for switchgrass for years, but the new research will provide much more information about the role of rainfall, genes, soil and other factors in the effectiveness of this common plant as an energy source.
One of the really interesting things with these grasses is that the climate in which they have found themselves has changed a lot over the last several hundred thousand years. As glaciers and climate change occurred, their populations were pushed south. And as glaciers retreated, the populations expanded north. The study lets us ask the really classic nature-nurture question. How much of the variation in the plant traits are driven by genetics or the environment or the interaction between genes and the environment?—Tom Juenger
The result is a grass that has adapted to a wide variety of environments throughout North America, from the hot and dry landscape of Central Mexico to the snowy climes of Canada. Understanding how switchgrass has adapted to vastly different regions and climates will provide information not only about how it would perform as a biofuel crop now in a given area, but also in future climates.
For the study, switchgrass plants will be grown in 14 test sites ranging north to south across the continent, from South Dakota to central Mexico. Data from the experiments will allow scientists to model and identify optimal traits for switchgrass in given areas. These include plant, microbe and soil traits that could be controlled by breeding, modifying the soil, tweaking the plant’s bacterial communities or even genetic manipulation.
The NSF grant funds a multipart project to study both switchgrass and a close cousin called panicgrass (Panicum hallii). Panicgrass has a simpler genome to that of switchgrass and is smaller, making it ideal for greenhouse studies.
Interest in developing genomic resources for P. hallii has been driven by its close relationship to the bioenergy crop switchgrass, Juenger said in a presentation this January at the conference “Plant and Animal Genome XXIII”. Much like upland and lowland ecotypes of switchgrass, there are two major ecotypes of P. hallii. P. hallii var. hallii is found in xeric (very dry) habitats and var. filipes occurs primarily in coastal mesic (well-balanced moisture) habitats.
Juenger and his colleagues have already used a variety of genetic and genomic tools to explore the genetic basis of this divergence, leveraging resources generated in collaboration with the DOE JGI.
The scientists will take two known varieties of switchgrass and cross them, creating what is known as a mapping population. Several hundred of these genetically distinct progeny will be planted in test sites to observe how the plants respond to different regions given the genes they inherit from the parental varieties.
Another part of the grant will allow the researchers to continue work done through a previous $4.6-million grant led by Juenger that looked at the response of switchgrass to varying levels of drought. Now, Juenger will examine whether years of rain or drought create epigenetic changes that can affect future performance in the grass when conditions switch from one extreme to another.
A final aspect of the NSF grant is an educational component: the training of future plant biologists. This component will be filled by Juenger’s Biology of Biofuels course, which is part of the university’s Freshman Research Initiative. In the course, first-year students study the physiology, genetics, breeding and ecology of switchgrass and compare it with other prospective biofuel sources.
Juenger’s colleagues on the Department of Energy grant are Kathrine Behrman, UT Austin; Jeremy Schmutz, HudsonAlpha Institute for Biotechnology; Tanja Wolke, Department of Energy Joint Genome Institute; Felix Fritschi and Alina Zare, University of Missouri-Columbia; Laura Bartley, University of Oklahoma; Julie Jastrow, Sarah O’Brien and Roser Matamala, Argonne National Lab; Damon Waitt, University of North Carolina at Chapel Hill; Denise Costich, International Maize and Wheat Improvement Center; UT Austin’s Brackenridge Field Laboratory; and the Lady Bird Johnson Wildflower Center.
Juenger’s colleagues on the NSF grant are Jeremy Schmutz, HudsonAlpha Institute for Biotechnology; Phil Fay, UT Austin Environmental Science Institute and the Department of Agriculture’s Agricultural Research Service; Tim Keitt, UT Austin Department of Integrative Biology; and David Lowry, Michigan State University.
David B. Lowry, Samuel H. Taylor, Jason Bonnette, Michael J. Aspinwall, Ashley L. Asmus, Tim H. Keitt, Christian M. Tobias, Thomas E. Juenger (2015) “QTLs for Biomass and Developmental Traits in Switchgrass (Panicum virgatum)” BioEnergy Research pp 1-12 doi: 10.1007/s12155-015-9629-7
Kathrine D. Behrman, James R. Kiniry, Michael Winchell, Thomas E. Juenger, and Timothy H. Keitt (2013) “Spatial forecasting of switchgrass productivity under current and future climate change scenarios” Ecological Applications 23:1, 73-85 doi: 10.1890/12-0436.1