For the first time, scientists have used genetic modification to increase the levels of multiple, rather than single, nutrients in a crop.

The first corn produced through the technique hasn't yet been tested for dinner-table safety, but if it succeeds, it may signal the development of a new, super-nutritious generation of GM foods.

"The major message of the paper is that it's possible to engineer crops with multiple nutrients," said study co-author Paul Christou, a plant biochemist at Spain's University of Lleida. "If you look at other nutritionally enhanced GM crops, up until now people have only been able to increase levels of one nutrient or vitamin."

An estimated 40 to 50 percent of the world's population suffers from nutrient deficiencies. The reasons for this are complex and sometimes political, but often involve reliance on a few staple crops that do not provide the nutrient balance common to mixed diets in the developed world.

Both conventional plant breeding and the high-tech activation of dormant genes are useful for adding some traits to crops, but they can't provide a sufficient nutritional boost. Neither can traditional forms of genetic engineering. When researchers attempt to add more than one new nutrient pathway, the genes tend to become scrambled in subsequent generations.

The approach used by Christou's group debuted last year in the Proceedings of the National Academy of Sciences, the same journal that published the latest corn research on Monday. It involves the bombardment of seed genomes with metal particles coated with desired nutrient-boosting genes. This produces a variety of different genomic configurations, some of which prove to be stable.

The researchers hope it will be more helpful than traditional techniques of nutritional genetic modification.

"We're aiming to produce transgenic plants in which you can provide as many nutrients as possible in one and the same seed," said Christou.

Christou's team tested the technique on a variety of corn common in South Africa that's known to produce low levels of beta carotene. Low levels of the nutrient can lead to blindness.

The resulting plants had double the usual amount of folate, sixfold levels of ascorbate and 169 times more beta carotene. At that level of expression, a single serving of corn can provide a recommended daily beta carotene intake.

The researchers are now experimenting with the addition of genes that enhance production of vitamin E, iron, zinc, calcium and other micronutrients, said Christou.

The study "shows the potential of this transgenic technology for accumulating genes that lead to micronutrient-enhanced crops," said Rodomiro Ortiz, a researcher at the International Maize and Wheat Improvement Center.

Further studies are needed to see if the new nutrients are correctly metabolized by humans, and if the plant is environmentally and toxicologically safe.

According to Christou, the research was funded entirely by public money. The team is trying to convince holders of patented techniques used in their process to allow researchers in the developing world to freely develop the technology. A model for this is the intellectual property guidelines of beta-carotene–enhanced Golden Rice.

"This is not a commercial story," said Christou. "This is aimed at people in developing countries."

See Also:

*Citation: "Transgenic multivitamin corn through biofortification

of endosperm with three vitamins representing three distinct metabolic pathways." By Shaista Naqvi, Changfu Zhu, Gemma Farre, Koreen Ramessar, Ludovic Bassie, Jurgen Breitenbach, Dario Perez Cones, Gaspar Ros, Gerhard Sandmann, Teresa Capella and Paul Christou. Proceedings of the National Academy of Sciences, Vol. 106, No. 17, April 27, 2009.

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*Image: The lower corn is transgenic; the upper is normal. Courtesy PNAS.

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