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Title: Overexpression of the maize Corngrass1 microRNA prevents flowering, improves digestibility and increases starch content of switchgrass

Author
item CHUCK, GEORGE - University Of California
item TOBIAS, CHRISTIAN - US Department Of Agriculture (USDA)
item SUN, LAN - Joint Bioenergy Institute (JBEI)
item KRAEMER, FLORIAN - University Of California
item LI, CHENLIN - Joint Bioenergy Institute (JBEI)
item ARORA, ROHIT - Joint Bioenergy Institute (JBEI)
item BRAGG, JENNIFER - US Department Of Agriculture (USDA)
item VOGEL, JOHN - US Department Of Agriculture (USDA)
item SINGH, SEEMA - Joint Bioenergy Institute (JBEI)
item SIMMONS, BLAKE - Joint Bioenergy Institute (JBEI)
item PAULY, MARKUS - University Of California
item Hake, Sarah

Submitted to: Proceedings of the National Academy of Sciences (PNAS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/11/2011
Publication Date: 10/20/2011
Citation: Chuck, G., Tobias, C., Sun, L., Kraemer, F., Li, C., Arora, R., Bragg, J., Vogel, J., Singh, S., Simmons, B., Pauly, M., Hake, S.C. 2011. Overexpression of the maize Corngrass1 microRNA prevents flowering, improves digestibility and increases starch content of switchgrass. Proceedings of the National Academy of Sciences. 108(24).

Interpretive Summary: The maize Corngrass1 (Cg1) gene encodes a microRNA that promotes juvenile cell wall identities and morphology. To test the hypothesis that juvenile biomass has superior qualities as a potential biofuel feedstock, the Cg1 gene was transferred into several other plants, including the bioenergy crop Panicum virgatum (switchgrass). Such plants were found to have up to 250 percent more starch, resulting in higher glucose release from saccharification assays with or without biomass pretreatment. In addition, a complete inhibition of flowering was observed in both greenhouse and field grown plants. These results point to the potential utility of this approach, both for the domestication of new biofuel crops, as well as for the limitation of transgene flow into native plant species.

Technical Abstract: Biofuels developed from biomass crops have the potential to supply a significant portion of our transportation fuel needs. To achieve this potential, however, it will be necessary to develop improved plant germplasm specifically tailored to serve as energy crops. Liquid transportation fuel can be created from the sugars locked inside plant cell walls. Unfortunately, these sugars are inherently resistant to hydrolytic release because they are contained in polysaccharides embedded in lignin. Overcoming this obstacle is a major objective towards developing sustainable bioenergy crop plants. We expressed a maize gene in Switchgrass and found that it created a potentially improved biofuel.