Scientists find way to increase corn's vitamin A

By Will Dunham

WASHINGTON (Reuters) - U.S. scientists have developed a way to breed corn that can boost the vitamin A it gives people who eat it -- a potentially important advance for regions of the world burdened by vitamin A deficiencies.

Vitamin A deficiency is an important cause of eye disease and other health problems in developing countries.

Corn, also known as maize, is the dominant subsistence crop in much of Latin America and sub-Saharan Africa, where up to 30 percent of children under age 5 are vitamin A deficient.

Scientists want to come up with ways to increase -- or "bio-fortify" -- levels of specific nutrients in crops like corn. Corn has precursors to vitamin A -- compounds called "provitamins" including beta-carotene -- which the body uses to make vitamin A.

Writing on Thursday in the journal Science, the scientists identified a naturally mutated gene that enhances the provitamin A content of maize. Based on this, they developed an inexpensive way to select the parent stock for breeding corn with the highest provitamin A content.

Choosing varieties that have this mutated gene can provide on average three-fold higher levels of provitamin A, the researchers said.

There are thousands of different corn varieties, and they differ greatly in provitamin A levels, the scientists said. White corn does not have provitamin A, but yellow varieties have it in varying levels.

A common existing technique for assessing the provitamin A content of corn varieties can be prohibitively expensive for plant breeders, the researchers said, but the new one is vastly less expensive.

"We've come up with a way to detect varieties that will produce high levels of provitamin A inexpensively," said one of the researchers, geneticist Edward Buckler of the U.S. Department of Agriculture and Cornell University in Ithaca, New York.

Buckler said the method does not involve the genetic modification of corn.

"Vitamin A deficiency is a big problem throughout the world, and it causes a lot of childhood blindness and a lot of immune deficiencies," Buckler said in a telephone interview.

Experts say vitamin A plays a key role in vision, bone growth, regulating the immune system and other functions.

"In parts of Africa, they eat maize three meals a day. And so if you can bio-fortify what they're eating a lot of, even just a small amount, it adds up," Torbert Rocheford, a professor of plant genetics at the University of Illinois at Urbana-Champaign who also worked on the study, said in a telephone interview.

(Editing by Maggie Fox and Kristin Roberts)