Folate-Rich 'Super Tomato' Could Cut Birth Defects

Gene technology could be used in rice, other staples in developing world

WEDNESDAY, March 7, 2007 (HealthDay News) -- You say tomato, scientists say "fewer birth defects."

U.S. researchers say they've created a folic acid-enriched "super tomato" that could cut the rate of birth defects, anemia and other folate deficiency-linked problems in the developing world.

"We used the tomato, because it is a very good model to work with," explained study co-author Andrew D. Hanson, professor of plant biochemistry at the University of Florida at Gainesville. "Now we want to move the strategy we have developed into cereal and tuber crops such as sweet potatoes."

Hanson's group published its findings in this week's Proceedings of the National Academy of Sciences.

Folate deficiency is associated with birth defects such as spina bifida and also with heart disease and some cancers. Grain products in the United States and other western countries are now fortified with folic acid, and pregnant women are advised to take folate supplements if necessary.

Unfortunately, folic acid supplies are much harder to come by in less developed countries, Hanson said, so genetically engineered crops could help prevent deficiency in those areas.

Hanson worked in close collaboration with Jesse F. Gregory III, professor of food science and human nutrition at UF. They targeted two molecular pathways by which tomatoes (and other plants) make folate -- one that produces a molecule called pteridine, the other producing another molecule, p-aminobenzoate (PABA). Those two molecules eventually become linked in the process that creates folate.

"Humans don't have the ability to produce parts of those pathways, which is why we require [folate] as a vitamin," Gregory explained.

In 2004, Hanson and Gregory reported that they had added a gene to the pteridine pathway in tomatoes. That doubled the tomato's production of folate.

"It was a synthetic gene, a DNA sequence based on a mouse gene," Hanson said. "But that engineered tomato plant was not good enough."

Keeping the engineered tomato plant intact, they added a second gene, this time one extracted from a weed called Arabidopsis. The gene is commonly used in plant genetic work on the PABA pathway.

That genetic manipulation resulted in a major increase in folate production, Hanson said.

"The tomatoes that we are reporting in this paper have very substantially elevated levels of folate," he said. "If the fruit is ripened on the plant, there can be 25 times more folate than normal."

The work is just beginning, he emphasized. "We have produced a few experimental plants," Hanson said. "This is a proof-of-concept study. With just two genes, it is possible to substantially increase the folate level of fruits. This is a demonstration that it can be done."

Now the goal is to show that the same increase in folate production can be achieved in plants that are dietary staples in many countries, he said.

"The most important targets of future work are cereal crops that are used around the world," he said. "Rice would be a major target. Various groups are working on this, and we are in partnership with them."

The Florida researchers have collaborations with centers in Britain, France, Belgium, Australia and African countries, Hanson said.

"We will also be trying other genetic engineering strategies," he said.

More information

There's more on folate deficiency at the U.S. National Institutes of Health.

SOURCES: Andrew D. Hanson, Ph.D., professor, plant biochemistry, and Jesse F. Gregory III, Ph.D., professor, food science and human nutrition, University of Florida Institute of Food and Agricultural Sciences, Gainesville, Fla.; March 6-9, 2007, Proceedings of the National Academy of Sciences
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