US team creates higher folate levels in plants
plants, sidestepping the need for taking supplements of the
vitamin.
Researchers led by Karel Schubert at Washington University in St Louis report that they enhanced levels of folate in the model plant Arabidopsis. They are currently investigating ways to enhance folate production in cereals, root and tuber crops to produce staple foods like rice and potatoes with high folate content.
"The results from our folate research project are a significant step in realizing the potential of biofortification - the fortification of plants through science - to meet the demands for improved human and livestock nutrition without relying on food and feed supplements," explained Roger Beachy, also president of Donald Danforth Plant Science Center in St Louis.
Plants are a major source of dietary folates, with green leafy vegetables, legumes and certain fruits being the richest sources of dietary folates. But many people do not eat enough of these foods to gain adequate intake of the vitamin to prevent neural tube defects in newborns.
Insufficient folate intake is the most common cause of birth defects like spina bifida and anencephaly. Women hoping to become pregnant are often advised to take supplements to prevent such problems. Folic acid is also thought to help prevent cardiovascular disease and is increasingly recommended to people at risk of the disease.
But not all consumers are keen on taking supplements and increasing dietary options could prove a valuable alternative.
In the study, published in the 6 April issue of the Proceedings of the National Academy of Sciences (vol 101, no. 14, pp 5158-5163), Schubert and colleagues describe studying one branch of a biochemical pathway in Arabidopsis that leads to the biosynthesis of folates. Arabidopsis is widely used in research as it is a good model for other plant systems.
They postulated that the levels of folate in plants could be enhanced by increasing the levels of the enzyme GTP cyclohydrolase-1, a key rate-limiting step along the pathway that leads to folate production. The team successfully cloned the folate-producing gene from the bacterium E. coli using a form of GTP cyclohydrolase-1 that is not similarly regulated.
The gene from E. coli was introduced into Arabidopsis. This resulted in an increase of the folate levels in the Arabidopsis leaf tissue to a level greater than the amounts typically found in spinach, a plant known to be rich in folates.
