GENET archive


Plant: Folate-rich ’Super Tomato’ could cut birth defects

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SOURCE: HealthDay News, USA

AUTHOR: Ed Edelson


DATE:   07.03.2007

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

WEDNESDAY, March 7 (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

                                  PART 2

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SOURCE: National Science Foundation, USA

AUTHOR: Press Release 07-022


DATE:   05.03.2007

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Research could provide vital daily nutritional requirement

Leafy greens and beans aren’t the only foods that pack a punch of folate, the vitamin essential for a healthy start to pregnancy.

Researchers now have used genetic engineering--manipulating an organism’s genes--to make tomatoes with a full day’s worth of the nutrient in a single serving. The scientists published their results in this week’s online edition of the journal PNAS, Proceedings of the National Academy of Sciences.

”This could potentially be beneficial worldwide,” said Andrew Hanson, a plant biochemist at the University of Florida at Gainesville who developed the tomato along with colleague Jesse Gregory. ”Now that we’ve shown it works in tomatoes, we can work on applying it to cereals and crops for less developed countries where folate deficiencies are a very serious problem.”

Folate is one of the most vital nutrients for the human body’s growth and development, which is why folate-rich diets are typically suggested for women planning a pregnancy or who are pregnant. Without it, cell division would not be possible because the nutrient plays an essential role in both the production of nucleotides--the building blocks of DNA--and many other essential metabolic processes.

Deficiencies of the nutrient have been linked to birth defects, slow growth rates and other developmental problems in children, as well as numerous health issues in adults, such as anemia.

”Folate deficiency is a major nutritional deficiency, especially in the developing world,” said Parag Chitnis, program director in the National Science Foundation’s Division of Molecular and Cellular Biosciences, which funded the research. ”This research provides the proof-of-concept for the natural addition of folate to diet through enhancement of the folate content of fruits and vegetables.”

The vitamin is commonly found in leafy green vegetables like spinach, but few people eat enough produce to get the suggested amount of folate. So, in 1998, the Food and Drug Administration made it mandatory that many grain productssuch as rice, flour and cornmeal be enriched with a synthetic form of folate known as folic acid.

Folate deficiencies remain a problem in many underdeveloped countries, however, where adding folic acid is impractical or simply too expensive.

”There are even folate deficiency issues in Europe, where addition of folic acid to foods has not been very widely practiced,” Gregory said. ”Theoretically, you could bypass this whole problem by ensuring that the folate is already present in the food.”

Will doctors be recommending a healthy dose of salsa for would-be pregnant women anytime soon? Probably not, the researchers say.

”It can take years to get a genetically-engineered food plant approved by the FDA,” Hanson said. ”But before that is even a question, there are many more studies to be done--including a better look at how the overall product is affected by this alteration.”

And there is another hurdle the researchers must clear. Boosting the production of folate in tomatoes involved increasing the level of another chemical in the plant, pteridine. Little is known about this chemical, which is found in virtually all fruits and vegetables.


Media Contacts?Cheryl Dybas, NSF (703) 292-7734 Hutson, University of Florida (352) 392-0400


                                  PART 3

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SOURCE: NutraIngredients, France

AUTHOR: Stephen Daniells


DATE:   06.03.2007

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06/03/2007 - Tomatoes, genetically engineered to contain high levels of folate, could provide the recommended daily amount in one standard serving, says new research.

Researchers from the University of Florida have created transgenic tomatoes that express 25 times more folate than normal tomatoes, and may offer up to seven times more folate than green leafy vegetables, considered a rich source of the vitamin.

Folate is found in foods such as green leafy vegetables, chick peas and lentils, and an overwhelming body of evidence links has linked folate deficiency in early pregnancy to increased risk of neural tube defects (NTD) - most commonly spina bifida and anencephaly - in infants.

This connection led to the 1998 introduction of public health measures in the US and Canada, where all grain products are fortified with folic acid - the synthetic, bioavailable form of folate.

”However, food fortification can be difficult to implement in developing countries due to recurrent costs, distribution inequities, and a lack of an industrial food system,” wrote lead author Rocio Díaz de la Garza. ”Folate enhancement in plant foods (biofortification) through metabolic engineering therefore represents an attractive alternative strategy to increase the intake of natural folates in rich and poor countries alike.”

Writing in the Proceedings of the National Academy of Sciences, the researchers report that by genetically engineering two different tomato strains to each overproduce one folate precursor (pteridine or p-aminobenzoate (PABA)), and then crossing these two strains, the resulting ripe fruit contained 25-fold more folate than normal tomatoes.

The tomatoes were transformed using the Arabidopsis aminodeoxychorismate synthase (AtADCS) and CTP cyclohydrolase I (GCHI) to lead to PABA, pteridine and folate hyperaccumulation.

Tomatoes that expressed both genes were found to accumulate about 840 micrograms of folate per 100 grams of fruit, enough to provide the RDA for a pregnant women ”in less than one standard serving,” said the researchers.

”To our knowledge, the folate levels we achieved are the highest reported for plants; our tomatoes accumulate up to seven times more folates than green leafy vegetables, which are considered rich folate sources,” they said.

The researchers also note that the concentrations of the folate precursors are likely at safe consumption levels, but stated that more research is required to fully assess the potential and safety of accumulated pteridines in GM fruit and plants.

”It should be noted that the success of our-two-gene biofortification strategy is likely to be repeatable in other plants… and may well be transferable to other food plants such as tubers and cereal grains,” concluded the researchers.

A number of genetically modified plants and crops are coming to light with enhanced nutritional content considered to offer human health benefits, including flavonoid-rich tomatoes, zeaxanthin in potato tubers, and the omega-3 fatty acid, eicosapentaeoic acid (EPA), to soybeans, brassica, and stearidonic acid (SDA) in canola crops.

However, no GM crops with potentially enhanced health benefits have been approved for human consumption. Sonsumer acceptance, particularly in Europe and most notably in the UK, continues to be one of the biggest challenges for these crops.

Source: Proceedings of the National Academy of Sciences

March 6, 2007, Volume 104, Number 10, Pages 4218-4222

”Folate biofortification of tomato fruit”

Authors: R.I. Díaz de la Garza, J.F. Gregory III, and A.D. Hanson




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