GM tomatoes to provide daily folate needs?
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
