By David Elstein
October 9, 2003

An Agricultural Research Service scientist and cooperators are developing new varieties of corn and other food crops that have higher levels of vitamin E.

Twenty-five percent of Americans do not get enough vitamin E. It is particularly important for pregnant women, and some researchers have shown that it can decrease the risk of heart disease.

The research was done by molecular biologist Edgar B. Cahoon of the ARS Plant Genetics Research Unit at the Donald Danforth Plant Science Center in St. Louis, along with his former colleagues at DuPont Crop Genetics, Wilmington, Del. The scientists used genes found in rice, barley and wheat, each of which contains high levels of vitamin E.

Now that their three years of research have led to a safe, healthful variety of corn, Cahoon and his colleagues are working on similar studies with soybeans. He believes many other crops would benefit from the new approach.

Vitamin E is a generic name for naturally occurring compounds called tocotrienols and tocopherols. Cahoon looked at the pathway that leads to tocotrienols, something that had not been studied much. The scientists were able to isolate a gene for the enzyme homogentisic acid geranylgeranyl transferase. This enzyme is responsible for producing a tocotrienol form of vitamin E in cereal grains. When the gene was added to corn plants, the kernels' vitamin E content increased sixfold.

In addition to making the crop more nutritious, boosting vitamin E levels is likely to increase the crop's shelf life. Vitamin E occurs naturally in vegetable oils, nuts and green leafy vegetables.

The research was reported in the September issue of Nature Biotechnology.

ARS is the U.S. Department of Agriculture's chief scientific research agency.

St. Louis, Missouri
October 7, 2003

Vitamin E corn: biotechnology for the consumer

From National Corn Growers Association

Recent advances in biotechnology promise benefits for consumers, in addition to farmers. Dr. Edgar Cahoon, a research molecular biologist with the USDA-ARS Plant Genetics Research Unit, and his colleagues from DuPont Crop Genetics have produced corn with six times the Vitamin E content of regular corn.

“Most of the biotechnology we hear about—Roundup-Ready soybeans, Bt corn—has been directed toward reducing the farmer’s input costs,” Cahoon says. “Our research, however, involves the development of a trait that improves the dietary quality of food.”

Vitamin E positively affects human health because it is a powerful antioxidant that protects cells from oxidation damage caused by “free radicals.” These radicals attack the cells’ membranes, proteins and DNA, contributing to the development of health problems such as heart disease, diabetes, cataracts and cancer.

Beyond human health benefits, the antioxidant qualities of Vitamin E will help corn resist spoilage caused by free radical-mediated oxidation, lengthening the shelf life of vegetable oils, which contain Vitamin E, and processed foods produced from those vegetable oils. Cahoon says the increase of Vitamin E in leaves and other tissues may also increase the productivity of corn plants in the field.

Although Vitamin E corn does have many other benefits, it was originally produced for a Pioneer Hi-Bred study aimed to improve the quality of corn for livestock feed applications. After studying how Vitamin E is made in cereal grains such as barley, wheat and rice, researchers identified a key gene responsible for the production of the vitamin in barley seeds and introduced that gene into corn seeds.

“The combination of the gene and where it is expressed gives the high level of this type of Vitamin E,” William Hitz, a Research Fellow with Pioneer Hi-Bred International, Inc. who was also involved in the project, says.—Not sure I understand this quote. What does high level mean? The paper cites a 10-15 fold increase.

This discovery, which could not have been accomplished by traditional plant breeding, shows biotechnology can benefit the consumer directly, Cahoon says.

Vitamin E corn must be tested extensively before it is available for consumers. First, it must be evaluated on its agronomic performance and its value in livestock feed applications. If these tests are successful, Vitamin E corn will be tested for regulatory approval, which can be time consuming.

“My best guess is five to seven years before this product is available, if it is decided that the trait will be commercially viable,” Cahoon says.

He says a new market for corn could be created with the commercial availability of Vitamin E corn since the antioxidant is isolated from vegetable oils for use in dietary supplements.

“By increasing the Vitamin E content six-fold, it is more likely that processors can use corn oil for the production of Vitamin E for nutraceutical applications,” Cahoon says.