Scientists claim to have discovered a method to increase the vitamin E content of corn seeds by up to six times, with future research to focus on soybeans. The findings could lead to a new generation of grain crops and other foods with therapeutic and health promoting properties for both humans and animals, say the researchers.
With soybeans becoming increasingly popular in the health food industry, a development of this kind could have strong, positive implications for suppliers and manufacturers of soybean-based products, such as the Bunge and Du-Pont joint venture Solae.
Dr Edgar Cahoon, a researcher with the USDA-ARS Plant Genetics Research Unit at the Donald Danforth Plant Science Center, and his colleagues from DuPont Crop Genetics, used a gene from an ordinary barley plant, which produces the enzyme homogentisic acid geranylgeranyl transferase (HGGT), a catalyst for tocotrienol biosynthesis in some plants.
Tocotrienols are the primary form of vitamin E in the seeds of plants, including staple food cereals such as rice and wheat. A powerful antioxidant, it has been shown to reduce both human serum cholesterol levels and also inhibit the growth of breast cancer cells.
Cahoon and his colleagues isolated the HGGT gene sequence from barley and introduced the gene into the model plant Arabidopsis thaliana. The scientists noted a 10- to 15-fold increase in the levels of vitamin E in the leaves of Arabidopsis. Similarly, insertion and over-expression of the barley HGGT gene in corn seeds resulted in a six-fold increase of vitamin E.
An additional benefit to this work is that it may lead to foods with a longer shelf life, said Cahoon. It is thought that foods with higher levels of vitamin E are protected from oxidative stress and that increasing the levels of these compounds may lead to enhanced agricultural productivity, as well as seeds and vegetable oils with improved storage properties.
"We were really quite amazed that this relatively small genetic change could result in such a large increase in the antioxidant content of Arabidopsis and corn," said Cahoon. "These results demonstrate the power of biotechnology for improving the nutritive value of crop plants."
Full details of the study can be found in the September 2003 issue of the journal Nature Biotechnology .