Africa: Science Team Boosts Nutritional Value of Vital Cassava

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America.gov (Washington, DC)

30 July 2008
Posted to the web 31 July 2008

Cheryl Pellerin

Field trials have begun in a bold effort to make cassava, the primary source of calories for 800 million people worldwide, a better provider of nutrition and increase its revenue-producing potential, especially for farmers in sub-Saharan Africa.

The three-year-old BioCassava Plus project -- funded since 2005 by more than $12.1 million in grants from the Bill and Melinda Gates Foundation -- has attracted a team of international scientists that is genetically engineering a range of valuable traits into the low-protein, virus-prone root crop that has a short shelf life and long processing time.

"We had eight objectives when we started the project," principal investigator Richard Sayre, a professor of plant cellular and molecular biology at Ohio State University, told America.gov. Five objectives were nutritional: The scientists sought to put the minimum daily allowances of protein, vitamins A and E, iron and zinc into a single 500-gram adult meal of cassava.

They also planned to make the crop more resistant to viral diseases, which reduce yields by 30 percent to 50 percent in many areas of sub-Saharan Africa; extend the plant's shelf life from one day to two weeks; and reduce cyanide toxicity. The cassava plant requires a three- to six-day processing regimen that must begin immediately after harvest to remove compounds that generate cyanide.

"Where we stand now," Sayre said, "is we've demonstrated proof of practice for all the target objectives in three years." The scientists created individual plants with each trait, and ultimately they will combine most or all of the traits into a single plant. The scientists also extended the shelf life of cassava using traditional breeding and a transgenic approach that is within six months of being tested.

"One advantage of transgenics is that it's fast when it works," he said, "so we can get a product in one year. With breeding [it takes] many generations, as many as 10, possibly."

BioCassava Plus partners are from research institutions in Colombia, Kenya, Nigeria, Switzerland, Tanzania, the United Kingdom and the United States.

ENGINEERING NUTRITION

Cassava is grown widely in tropical Africa, Asia and Latin America. It is the developing world's fourth most important crop, with production in 2006 estimated at 226 million metric tons, according to the U.N. Food and Agriculture Organization (FAO).

Cassava is the staple food of nearly 1 billion people in 105 countries where the root provides as much as a third of daily calories. But average cassava yields are barely 20 percent of those obtained under optimum conditions.

To engineer a better cassava plant, the scientists began with a model cultivar from Africa -- a variety of a plant that is created or chosen and maintained through cultivation. For each targeted trait, the team transferred into the cassava plant genes from other plants, including cassava, and sometimes bacteria, that could confer the desired traits.

The transgenic plants then went through a rigorous biosafety approval process in the United States and were tested in model systems -- like human cell lines and sometimes animals -- before they were allowed to be grown outside in field trials.

BioCassava Plus now has field trials in progress at a U.S. Department of Agriculture site in Puerto Rico and is working with partners from the University of Puerto Rico-Mayaguez.

"We have at least three traits in the field and we anticipate having two and maybe more coming by the end of the year," Sayre said.

The next step is to hold field trials in Africa with partners in Kenya and Nigeria in 2009. After these trials, the scientists can begin the process of combining traits into a single plant.

"Africa is in the process of establishing biosafety regulations for transgenics in most of the countries, Sayre said. Four or five countries, including Kenya and Nigeria, have rules in place, he added, and two have transgenics in commercial production.

"We won't consider countries that don't have biosafety programs," Sayre said.

A preliminary cassava product release -- potentially within five years -- will have four or five traits, including virus resistance, higher protein, iron and vitamin A.

Ultimately, Sayre said, "when all these traits get stacked into what will be a farmer-preferred cultivar from Africa, this work will be done by African scientists in African laboratories. We're developing the tools mostly in the United States and Europe, but once those tools are in place, it becomes an African-owned and developed project."

CASSAVA PARTNERSHIP

Another group gathered in July to discuss the future of cassava. At a global conference in Gent, Belgium, cassava scientists who are part of a national network called the Global Cassava Partnership called for an increase in investment in research and development needed to boost farmers' yields and explore promising industrial uses.

The meeting was the first global scientific conference of the Global Cassava Partnership, a consortium formed under the FAO-facilitated Global Cassava Development Strategy by international organizations.

These included FAO, the International Center for Tropical Agriculture, the International Fund for Agricultural Development, the International Institute of Tropical Agriculture, national research institutions, nongovernmental organizations and private partners.

Participants reviewed the state of cassava production worldwide and future prospects. They agreed on new projects that will be offered to the donor community and a set of investments needed if cassava is to realize its full potential in addressing the global food and energy crisis.

More information about BioCassava Plus is available on the project's Web site.

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