Cassava packs a protein punch with bean genes

A DEADLY poison could save the lives of millions of African children, thanks to the discovery that cassava can be duped into turning about half of the cyanide it makes into extra protein.

Although cassava is a major source of carbohydrates for 700 million people, mostly in Africa, it normally contains only small amounts of protein. Claude Fauquet of the Danforth Plant Science Center in St Louis, Missouri, and his team bumped up the protein content to 12.5 per cent by adding bean and maize genes to make a protein called zeolin. They were surprised to find that the plant used its natural supply of cyanide to provide the building blocks of the new protein. "Cyanide is a source of nitrogen within the plant," explains Fauquet.

While non-modified cassava supplies just one-fifth of daily protein requirements, the extra protein is enough to supply the needs of infants on a typical cassava-based diet (PLoS One, DOI: 10.1371/journal.pone.0016256). Fauquet says his root could save 1 in 4 African children from a potentially fatal condition called protein-energy malnutrition.

However, it will be some years before it is rolled out. Although identical to the one eaten by a billion people worldwide, the added bean protein resembles one that causes rare allergic reactions. So the team has developed another version with extra protein from sweet potatoes that won't cause allergies. "We hope to launch it in Africa in four to six years," says Fauquet. He adds that the project, which is funded by the Bill and Melinda Gates Foundation, is purely humanitarian so the cassava would be offered free to poor farmers.

Other modified staples include the "protato" developed in India, and aubergines, recently denied approval in India because of objections from groups opposed to genetically modified crops.

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