May 6 2010
Meeting our demand for food and fuel with corn may not be as difficult previously suspected. Researchers at the University of Minnesota conducted genetic studies of corn varieties and found that corn can be bred to optimize properties for cellulosic ethanol without adversely affecting the grain yield.
In the U.S., corn grain is a major source of animal feed, human food, and fuel ethanol for cars and trucks. The proportion of domestic corn grain used for producing ethanol increased from less than 10% in 2000 to about 30% in the last two years. Concerns have been raised on whether the ever-increasing demand for corn ethanol is contributing to higher food prices in your local grocery store.
To help address this food vs. fuel concern, the US Department of Agriculture and Department of Energy are promoting the development of plant feedstocks suitable for producing cellulosic ethanol. In this scenario, plant materials rich in cellulose (such as leaves, stalks, or woodchips) are broken down into sugars that are fermented into ethanol. Corn grain would then be harvested for feed and food while a portion of the corn stover-the leaf, stalk, tassel, and cob residues that are normally left to rot in the field—would be collected and used to produce fuel.
Since the 1920s, hybrid corn varieties grown by U.S. producers have been bred for high grain yield and superior agronomic performance. But these varieties have not been bred for qualities that would make their stover suitable for producing cellulosic ethanol. Could tomorrow’s corn have high grain yields and superior stover quality for cellulosic ethanol? Or would breeding for cellulosic ethanol adversely affect grain yield and agronomic performance? In other words, can we have our corn and eat it, too?
Genetic studies conducted by Professor Rex Bernardo and Dr. Hans-Joachim G. Jung of the USDA-Agricultural Research Service, and graduate students Magan F. Lewis and Robenzon E. Lorenzana at the University of Minnesota have indicated that breeding for such dual-purpose corn hybrids is feasible. These studies, which were funded by the USDA-DOE Plant Feedstock Genomics program, were reported in the March-April 2010 issue of Crop Science published by the Crop Science Society of America.
The research team found either neutral or favorable relationships among grain yield, stalk lodging, and stover-quality traits considered most important for producing cellulosic ethanol. Even though current corn lines have not been bred for cellulosic ethanol, they exhibited a significant amount of genetic variation for the stover-quality traits. DNA fingerprints indicated the lack of “silver-bullet” genes for cellulosic ethanol: instead, stover-quality for cellulosic ethanol is controlled by many genes that need to be accumulated in a corn hybrid by selective breeding.
Bernardo is now investigating the use of DNA fingerprints and year-round breeding nurseries in a fast-track approach to breed for dual-purpose corn. He and Jung remain cautious, however, on the prospects of large-scale production of corn for grain and cellulosic ethanol on U.S. farms. “What we’re studying is the first small piece of the puzzle,” Bernardo said, “and big pieces of the cellulosic-ethanol puzzle remain to be solved.” In particular, how much of the corn stover can be removed from the field without adversely affecting soil quality? Can corn stover be efficiently transported and stored? And will the demand for cellulosic ethanol be large enough to entice seed companies, who develop virtually 100% of the corn hybrids grown by farmers, to begin developing dual-purpose corn hybrids?
While scientists continue to answer these questions, corn breeders can work to improve corn yields for both our stomachs and our distilleries.
This research is based on two journal articles. The abstract for one can be viewed for no charge for 30 days at http://crop.scijournals.org/cgi/content/abstract/50/2/516
The full article is available for no charge for 30 days following the date of this summary. View the abstract at http://crop.scijournals.org/cgi/content/abstract/50/2/541.
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