Volume 8, Number 2, 1999


Understanding corn's genetic maze

Three UD researchers have teamed up with scientists at the University of Illinois and Massachusetts General Hospital to become one of only 24 groups nationwide to receive a National Science Foundation (NSF) award for mapping the genetic material of crop plants.

Under the $2.2 million, three-year grant, the team will attempt to decipher the genetic coding sequences responsible for corn's oil content.

Bertrand Lemieux and James Hawk of UD's Department of Plant and Soil Sciences and John S. Boyer, E.I. duPont Professor of Marine Studies, hope to pinpoint-and perhaps manipulate-the genetic messages tied to corn oil production.

Because producing healthy chickens is big business for the Delmarva region's poultry industry, producers and growers currently boost the energy value of chicken feed by supplementing it with left-over cooking oil from fast-food restaurants.

Corn containing more than 6 percent oil might give the poultry industry an alternative to this time-consuming practice, by providing a higher energy, more nutritious feed source, according to Lemieux.

And, a larger harvest of natural, vegetable oil could help replace some of the chemically modified oils found in many processed foods, says Boyer. When oils are modified to prolong their shelf life, Boyer says, the chemical process generates certain molecular structures tied to questions about negative health effects.

"The ability to produce oils in a desired amount, with the right properties, could be
very advantageous to consumers, and to chemical companies, which are increasingly looking to the life sciences for new products and solutions," Boyer says.

Because cells from corn and human beings contain about the same amount of the genetic blueprinting material, DNA (deoxyribonucleic acid), finding specific coding sequences can be a daunting task, Boyer says. A key to the project will be Lemieux's expertise with new genome research technologies based on DNA. Unlike conventional analytical techniques, DNA chips allow for thousands of parallel experiments to be done simultaneously.

This strategy will allow the UD team to better analyze seeds provided by University of Illinois researchers, who manage "the world's longest running selection experiment involving any organism," says Hawk, a plant breeder. Efforts to breed improved corn varieties began in the late 1890s at Illinois, he adds.

After the UD researchers identify the corn genes involved in oil deposition in seeds, Lemieux says, Hawk can then use those sequences as "DNA markers," to support rapid corn-breeding experiments. "I'll cross the high-oil varieties with other sources and see if we can further increase oil deposition," Hawk explains.

Boyer's previous investigations of maize subjected to drought conditions should help the UD researchers locate oil-related corn genes. The oil content of corn tends
to drop when the plant is exposed to dry conditions, he says. This suggests that "some of the genes that regulate oil deposition are involved in the drought response."

In simple terms, Lemieux says, "We're going to identify genes based on where and when they're expressed. Then, we're going to follow the inheritance of these genes and compare it to that of oil content in maize kernels."

-Ginger Pinholster