From sequencing the first tree genome to follow-on discoveries for better bioenergy crops, Gerald Tuskan has spent his career opening up new avenues of research to enable a thriving bioeconomy underpinned by technological advancement.
Tuskan, director of the Center for Bioenergy Innovation and a Corporate Fellow at the Department of Energy’s Oak Ridge National Laboratory, presented his remarks during a lecture on November 19 after DOE leadership honored him as a 2024 Office of Science Distinguished Scientist Fellow. He described a career journey that was supported by the multidisciplinary, collaborative environment inherent in DOE’s national laboratory structure.
Tuskan’s research has been largely tied to new uses for Populus, or “the people’s tree” in Latin — a genus that includes poplar, cottonwoods and aspen. Populus is the fastest growing temperate woody species in North America. The tree is easy to root even from bare sticks and has been relied on throughout history, including as a shade tree for Roman cities and roads, he said.
The Lewis and Clark expedition carved their dugout canoes from cottonwood trees along the Missouri river, he added. The word “alamo” means “poplar tree” in Spanish, and the mission where the Battle of the Alamo occurred was named after a giant cottonwood that grew there. “Without Populus, we may be saying ‘Remember the Post Oak,’ which does not sound quite as attractive,” he told the audience.
The tree is easily engineered to enhance traits like drought tolerance and nutrient efficiency. One of the missions of the DOE Center for Bioenergy Innovation (CBI) at ORNL is to create bioenergy crops like Populus trichocarpa that can thrive on non-agricultural lands. Populus produces abundant lignin, the most abundant polymer on the planet, that allows plants to grow upright. CBI is also developing efficient ways to use microbes to convert plant lignin into jet fuel.
Tuskan described camping with his family as a teenager beneath massive cottonwood trees along the Verde River in central Arizona. He later studied forestry at Northern Arizona University, where he had his first, and very influential, genetics class. He earned his master’s in forest genetics at Mississippi State, where he looked at genetic diversity and biomass production in the sycamore tree. Tuskan earned his PhD in genetics at Texas A&M, where he continued his studies on plant genomics and biomass yield. His first job out of college was at North Dakota State University, where he studied the use of poplar plantings to prevent erosion of farmland soils.
Tuskan was then hired at ORNL to manage woody crops research under the Biofuels Feedstock Development Program. One of his first projects at the lab was analyzing the regeneration of aspen trees after wildfire swept through Yellowstone National Park in 1988. And in one of his more interesting early DOE missions, he traveled to Ukraine after the Chernobyl nuclear accident, exploring the use of poplar and willow as natural remediation solutions for cesium and strontium contamination.
He recounted many successful collaborations with colleagues at ORNL and beyond as he explored the genetic underpinnings of desirable physical traits in poplar. Tuskan led a multi-year project that sequenced the first-ever tree genome, resulting in an article on the cover of Science in 2006 that laid the groundwork for development of Populus trichocarpa as an ideal feedstock for plant-derived fuels.
The project was also the first report of the plant microbiome, as Tuskan and partnering scientists sequenced the bacteria, archaea and fungi found in the leaves and roots of the tree. That discovery made possible today’s research into plant-microbe interactions that are fundamental to plant growth and function.
He and collaborators went on to sequence the genomes of switchgrass varieties, kalanchoe, and eucalyptus, along with associated bacteria and fungi. A follow-up Populus genome-wide association study has enabled numerous projects identifying gene-to-trait linkages controlling plant size, yield, and hardiness, as well as unexpected discoveries such as genes that cause similar conditions in trees and humans.
Tuskan also served as co-lead for the Plant Genomics Program at the DOE Joint Genome Institute before he took the helm as director of CBI in 2017.
He noted discoveries that are being made possible today by new capabilities such as the Advanced Plant Phenotyping Laboratory at ORNL, a high-throughput, robotic phenotyping system that quickly gleans critical plant data using a suite of hyperspectral imaging stations.
The Distinguished Scientist Fellowship is accompanied by a $1 million award for new research, which Tuskan said will go to exploring the optimization of eucalyptus as an annual crop. The abundance of terpenes gathered from the plant can be quickly and easily upgraded into chemicals and fuels, he noted.
Tuskan emphasized the collegial nature of his many research accomplishments as he closed his remarks.
“The award is given to one person, but really it represents a combination of very bright and hardworking people,” Tuskan said. He described how he became a better biochemist, project manager, ecologist and more by working with and learning from colleagues.
“The 21st Century has been called the century of biology by lots of people,” Tuskan said. “We are currently poised, thanks to DOE’s investment, to achieve bold discoveries and disruptive technologies that will create domestic jobs, reduce our dependence on foreign oil, and help evolve the emerging bioeconomy.”
The lecture is available to view online.
UT-Battelle manages ORNL for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.