People familiar with agricultural biotechnology remember the decisions a few years ago of some sub-Saharan African countries to reject offers of biotech corn as food aid. The cassava mosaic virus has infected much of the cassava crop in central Africa, a food staple for over 250 million people, and governments are rejecting biotech cassava as a way to combat the impact of the mosaic virus.

Cassava is known as a “poor person’s crop” and an “orphan crop” that is little researched by for-profit international biotech companies. It is a perennial woody shrub with an edible root that is native to Brazil and Paraguay, also known as yucca, manioc or tapioca, and was originally carried to Africa by Portuguese traders. Cassava grows well in poor soils and can use a little or a substantial amount of water. It is unique in that it can be harvested after six-eight months of growth or the roots can be stored in the ground for as much as three years. Once harvested, the roots are highly perishable. Consumers usually boil it like a potato or grind it into flour. The leaves can be consumed as a cooked vegetable and are a good source of vitamin A and B with about 8-10 percent protein on a fresh weight basis. Cassava also has industrial uses as a binding agent in the production of paper and textiles.

Cassava is the number one starch crop in Africa producing over 100 million metric tons per year. Corn is number two at about 40 million metric tons. Yields have been cut 30 to 40 percent under the worst mosaic virus infections. Cassava was a resurgent crop in the 1990s as new varieties dealt with other pest problems and industrial uses were developed.

While major companies have not invested in new technology for the cassava, foundations and government agencies concerned about hunger in Africa and other parts of the world have developed programs to increase the nutritional content of cassava. It is low in protein, key minerals and vitamins and can have excess amounts of cyanide. The Bill and Melinda Gates Foundation recently awarded a $7.5 million, five year grant to a group of researchers at 10 different institutions headed by Dr. Richard Sayre, a Plant Cell and Molecular Biologist at Ohio State University. The BioCassava Plus group will develop novel transgenic cassava germplasm to make it a more complete food source with a longer storage life and elevated viral disease resistance.

The Donald Danforth Plant Science Center will receive about $3.3 million of the grant to extend its research on cassava. The Danforth Center and its International Laboratory for Tropical Agricultural Biotechnology used biotechnology to create immunity to the mosaic virus in cassava plants. New plants are usually grown from a cutting of an existing plant rather than from seeds. The virus is spread by the cuttings of the old plants used to grow new plants and by bites of a virus carrying whitefly.

When a new pest like the mosaic virus in cassava becomes a production constraint, researchers have three basic options. They can find strains that are resistant to the pest and cross that resistance into existing local varieties. They can also seek out pesticides that can control the condition, or they can use biotechnology to produce resistance to the pest.

Finding natural resistance and then breeding it into currently used varieties is a slow process that requires the work of scientists that are in short supply. Biotechnology can usually cut the development time by over 50 percent. Small-scale farmers often do not have the money or familiarity with chemical pesticides to make that option a viable alternative.

Familiar arguments are used against the biotech cassava. Opponents state that more food is not the answer to starvation. That is true in rich countries like the U.S., but in countries where up to 80 percent of the people make their living in agriculture, higher yields are critical. With 250 million people in Africa depending on cassava as a food staple, ignoring the problem does not offer much of an answer.

As noted earlier, cassava is considered a poor man’s crop. Given its ability to grow in poor soils and its flexibility of harvest that protects against the impact of short-term droughts, the Gates Foundation approach of improving the nutritional quality and disease resistance of cassava seems like a reasonable response. Also, the expanding industrial use of cassava prior to the mosaic virus problem indicates the potential for it to be more than a subsistence crop. Cassava can be a cash crop to pay for other foods to balance diets, medicine to cure common ailments and education for children.

The cassava mosaic virus is not the latest pest to infect African crops. Scientists are already developing strategies for a strain of wheat rust first found in Uganda in 1999 that has now infected the Kenyan and Ethiopian wheat crops. Local varieties developed as part of the “green revolution” that began in the 1960s have been resistant to previous strains of wheat rust for the past 40 years. The greatest concern is for small-scale farmers who lack the money to buy chemicals to control the disease. International wheat breeders have 165,000 different genetic varieties of wheat to search through to find a strain resistant to the new rust. Biotechnology could play a role in finding a solution to this latest crop problem in Africa.

The problems with cassava and wheat in Africa are a subset of the problems of people living in rural areas who do not have access to modern food production technology. Biotechnology is increasingly seen as one of the tools for scientists to use to address real issues of hunger among small-scale farmers in developing countries.