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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, March 2007 by Ed
Edelson.

"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 1/8folate 3/8 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.

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