Corn for food and fuel

Meeting our demand for food and fuel with corn may not be as difficult as previously suspected. Researchers at the University of Minnesota conducted genetic studies of corn varieties and found that corn can be bred to optimise properties for cellulosic ethanol without adversely affecting the grain yield.

In the US, 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 supermarkets.

The US Department of Agriculture and the Department of Energy are promoting the development of plant feed stocks suitable for producing cellulosic ethanol. 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.

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 dual-purpose corn hybrids is feasible.

The research team found either neutral or favourable relationships among grain yield, stalk lodging and stover-quality traits are 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 also 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 US 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.”