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Switchgrass May Unlock the Future of Biofuel
by Silke Schmidt (Phys.Org) ... Genetically modifying switchgrass could boost crop yields and its commercial viability.
But to close in on realizing that potential requires one small tweak: a genetic sterility switch that prevents the modified grass from contaminating the genes of nearby unmodified grasses. Dazhong "Dave" Zhao, a UWM associate professor of biological sciences, hopes to build that switch.
Switchgrass is an attractive biofuel feedstock because it can grow on marginal lands of little agricultural value. It also requires less chemical fertilizer than corn, the dominant source of ethanol currently mixed into unleaded gasoline. "Grasses can grow anywhere and are not in competition with human food production," Zhao says.
In addition to being a low-input and fast-growing crop, switchgrass can survive for 10 years or more, while corn must be sown at the start of each growing season. Last but not least, switchgrass greatly reduces erosion by holding soil in place while providing habitat for birds, insects and other wildlife.
To make biofuel production more sustainable, Zhao and postdoctoral researcher Jian Huang are tackling the main obstacle keeping genetically modified switchgrass off the commercial market. It's the possibility that lab-engineered genes could escape human control by mixing with genes of wild-growing grasses, which might interrupt natural processes in unpredictable ways.
Under current federal regulations, only genetically modified grasses that are absolutely sterile in the lab can enter field trials. That's where researchers determine whether sterility and other introduced properties can be maintained long-term in real-world conditions.
Zhao hopes to create sterile switchgrass by introducing a fusion gene
into its reproductive cells, using a harmless bacterium as a delivery vehicle. The fusion gene merges the Solo Dancers, or SDS, gene – an essential player in the reproduction of many plant species – with a toxic gene called Barnase.
"By combining the SDS and Barnase genes, we have created a new gene with very specific toxicity: It kills only the tissue that makes a plant's version of eggs and sperm," Zhao says. The new gene acts without affecting plant growth or flower development. READ MORE