Cassava Rising

Cassava Rising

“Breeding Cassava” by Nagib Nassar and Rodomiro Ortiz, in Scientific American, May 2010.

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1m 40sec

To many Americans, cassava root is a stranger in the produce aisle. But for 800 million people around the world, the starchy tuber (also called manioc, tapioca, and yuca) is the main staple of their diets. Globally, it accounts for more calories consumed than any crop besides rice and wheat. Unfortunately for those who subsist on it, it’s not particularly nutritious, containing little protein, vitamins, or minerals. A new and improved cassava could go a long way toward alleviating malnutrition in the developing world, and that’s just what University of Brasília geneticists Nagib Nassar and Rodomiro Ortiz have set out to create.

Cassava originated in Brazil, but in the 16th century Portuguese sailors brought it to Africa, which today produces more than half the world’s supply. From there it spread across tropical Asia as far as Indonesia. It can be fried, boiled, turned into flour, even consumed raw. In some parts of Africa and Asia, people eat the plant’s leaves as well. Yet despite its widespread reach and versatility, the lowly cassava has never attracted much attention from scientists. Average yearly yields are low, leaving plenty of room for improvement.
Along with their colleagues, Nassar and Ortiz are cross-breeding the common, domesticated plant with its wild relatives in the hopes of creating hybrids that are more nutritious, hardier, and more drought resistant. Wild varieties of cassava are rich in essential amino acids, iron, zinc, and, importantly, beta carotene, which helps ward off eye diseases, a major problem in countries with high malnutrition rates. One new variety of cassava has 50 times as much beta carotene as the common plant.

Despite such advances, the authors and other cassava researchers have their hands full: The New York Times recently reported that a new and damaging virus is destroying crops around Lake Victoria, and may soon spread across Africa. Scientists will need to develop a resistant variety and distribute it quickly, or widespread food shortages will be on the horizon.

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