Corn cuts the carbs
Low-sugar, high-protein maize may help the malnourished.11 May 2004
A genetically engineered breed of corn with half the usual amount of carbohydrates but double the fat and protein has been created by researchers in California.
If the prototype corn can be grown commercially it could find a market among the crowd following low-carbohydrate diets, for whom standard sweetcorn is not allowed.
But creator Daniel Gallie’s main hope is that the new corn breed will supplement protein-deficient diets in Africa and South America. It might also prove a boon to farmers who want high-energy corn for their pigs and chickens.
Gallie and his colleagues of the University of California, Riverside, stumbled on the low-carb corn when studying its flowers, which come in pairs called florets. Normally, only one floret in each pair is pollinated and this survives to make a corn kernel, similar to those on ears of sweetcorn.
Inside each kernel is an embryo rich in protein and oils, which will sprout a new seedling, and a carbohydrate-rich endosperm that nourishes it.
Gallie genetically engineered corn plants so that the flowers produce a hormone that enables both florets to survive and to be pollinated. The resulting corn kernels contain two embryos and a smaller, squashed endosperm. Consequently, the corn packs double the normal amount of protein and fat and half the carbohydrate1.
Gallie says the low-carb trait might be bred into other strains of corn and that several companies are interested in developing the crop. But like any genetically engineered crop, it would have to clear regulatory and ethical hurdles before it could be sown.
The corn must overcome other obstacles if it is to prove useful, say experts. If US farmers are to adopt it, for example, it will have to produce yields as high as today's commercially grown crops, says Brian Larkins who studies maize at the University of Arizona, Tucson.
And if the corn is to be used in developing countries, researchers must ensure that the high levels of fat and protein do not interfere with people’s ability to mill and cook it, Larkins says. "It's an interesting and bizarre kernel but it is not a slam dunk," he says.
Protein poor
Malnutrition because of lack of calories is usually accompanied by a dearth of protein. In fact, 'protein-energy malnutrition' is the leading cause of death in children in developing countries.
Researchers have tried for some time to breed high-protein corn, with some success. One type, called Quality Protein Maize is a natural mutant that makes more of one low-level protein building block called lysine. It is already grown in countries such as Africa and China, but requires continual breeding to ensure that the mutation is kept in the crop.
Experimentally, some researchers have tried genetically engineering corn to boost production of particular amino acids essential in the human diet. "It is important to have more of the right protein," says Joachim Messing who has pursued such work at Rutgers’ Waksman Institute in Piscataway, New Jersey.
In the United States, however, only a fraction of corn is used for human food. Over 70% is used to feed livestock, 20% to make the corn starches or oils that find their way into numerous foods, and around 5% is milled for dry products such as corn chips.
© Nature News Service / Macmillan Magazines Ltd 2004