Seasoning rice with daffodil and bacteria genes, scientists have boosted the vitamin A content of the developing world's most widely consumed grain in the hope of ending a common dietary deficiency that kills 1 million poor children every year, according to research made public Thursday.
Moreover, the researchers deliberately developed the genetically modified rice without commercial support so that they could give the seed away to farmers--free of the patent or licensing restrictions that so often limit the distribution of genetically engineered crops.
The World Health Organization estimates that 230 million children are at risk for vitamin A deficiency in regions where rice is a staple of the daily diet. In Southeast Asia alone, a quarter of a million children go blind every year because of this dietary problem.
The vitamin deficiency may cause one of every four child deaths in regions where it is prevalent, UNICEF officials said. Researchers now are working with rice centers in China, Southeast Asia, India, Africa and Latin America to incorporate the new strain into the most bountiful local varieties. After it undergoes the necessary health and safety tests, the new rice could be available to farmers within the decade.
Laboratory tests indicate that the plants can provide enough beta carotene for the body to manufacture the recommended dietary allowance of vitamin A from a daily ration of rice.
"Given how much of the world eats rice every day, this could have a huge impact," Dartmouth College plant geneticist Mary Lou Guerinot said. The new transgenic rice "exemplifies the best that agricultural biotechnology has to offer a world whose population is predicted to reach 7 billion by 2013."
After normal milling and cooking, rice kernels do not naturally contain the carotenoid compounds that the human body transforms into vitamin A.
Without enough of the necessary vitamin in their diet, people develop chronic ailments, from blindness to a weakened immune system that leaves the young especially vulnerable to infections. Infants in developing countries, who often are weaned on a rice gruel, are most at risk, said Ken Brown, director of the UC Davis international nutrition program.
To remedy the problem, an international team led by Ingo Potrykus at the Institute for Plant Sciences in Zurich, Switzerland, successfully used three new genes--two from the daffodil and one from a bacterium--to create a variety of rice that contains enough beta carotene to meet the Vitamin A requirement with a typical daily ration of rice. A fourth gene, which allowed researchers to track the genetic changes, also was added.
Their work is being published today in the journal Science.
"My team targeted vitamin A deficiency because this is one of the largest health problems worldwide," said Potrykus in Zurich. "It was an experiment that was so complicated that the scientific community did not believe it would work. Nobody had tried to transfer four independent genes" into rice.
At an international botanical congress in St. Louis earlier this year, Potrykus announced that his group also was trying to modify rice to increase its iron content and promote absorption of dietary iron. Iron deficiency is the most common nutritional disorder in the world.
The new transgenic vitamin A rice may be the first to actually improve a crop's nutritional value to make it a better food, several experts said.
Although farmers now routinely plant millions of acres every year with genetically engineered corn, soybeans and other crops, most commercial transgenic plants are designed to make crops cheaper and more efficient to cultivate, not make them more beneficial to eat.
"For any important crop, this is probably a first for improving the nutritional profile," said UC Davis plant pathologist Pamela Ronald. "This is the beginning of a lot of things in biotechnology that will benefit consumers, especially in the Third World."
The new strain of rice is a rich yellow in color, reflecting the high levels of beta carotene it contains.
Unlike more traditional vitamin A supplements, there is no danger with the transgenic rice that someone could consume a toxic dose of the vitamin--only five times the daily requirement--because the body naturally limits the amount of beta carotene it processes.
Not so long ago, rice was mostly overlooked in the race to genetically engineer the world's foodstuffs.
But with a genetic structure about 40 times smaller than that of wheat--and therefore less complex--rice has become one of the most important cereal crops for genetic experiments. Indeed, the interest in rice has grown so intense that scientists expect to have completely deciphered the 25,000 genes in its genome by early next year, several plant geneticists said.