The Donald Danforth Plant Science Center announced on September 6 that it has received additional funding totaling $11.9 million for the Virus Resistant Cassava for Africa (VIRCA) project. Funds will be used to develop and deliver farmer-preferred cassava varieties enhanced to resist serious plant virus diseases that are greatly reducing crop yield.
The additional funding came from the Bill & Melinda Gates Foundation ($5.6 million), The Monsanto Fund ($5.4 million) and the Howard Buffett Foundation ($860,000). VIRCA is also supported by USAID from the American people ($2.5 million).
Two products will be developed. The first product will incorporate virus resistance in a popular cultivar which is favored by farmers in Uganda and the Lake Victoria region. A second product will be developed in the traditional Ebwanateraka cultivar, in which virus sequences will be stacked to impart resistance to two viruses. Known as the “Queen” of cassava for its taste and texture as well as its flexibility in harvesting time, Ebwanateraka has been virtually wiped out in the Uganda region due to the two viral diseases.
VIRCA-II is a collaboration between researchers at the Donald Danforth Plant Science Center in St Louis, MO, the NaCRRI, and the Kenya Agricultural Research Institute (KARI). The team will build on achievements made in VIRCA-I, during which gene silencing demonstrated success in controlling both diseases in transgenic cassava plants. Control of CMD associated with several-fold improvement in storage root yields was recently demonstrated in early field trials in Uganda.
Cassava is one of the most important staple food crops for more than 200 million sub-Saharan Africans who derive 25 percent of their daily calorie intake from the starchy tuberous roots. In the East African countries of Uganda, Kenya, Tanzania, Mozambique, Rwanda, Burundi and Malawi, approximately 130 million people depend on the crop and produce nearly 30 metric tons of cassava annually. Cassava also contributes more than any other single crop to household income, with 63 percent of households selling cassava products.
Despite its natural drought tolerance and ability to grow well on marginal lands, cassava is susceptible to various pathogens. At least one third of the continental harvest is lost each year to Cassava Mosaic Disease (CMD) alone. Cassava Brown Streak Disease (CBSD), another viral cassava disease, is considered to be among the most dangerous plant diseases in the world for the threat it poses to food and economic security throughout Africa.
In East Africa CBSD is considered a more immediate threat to cassava production than CMD because of the significant increase in geographical distribution in recent years and the dramatic effect this virus has on both yield and quality of cassava storage roots. CBSD symptoms are more subtle than CMD and may be hard to detect on leaves and stems, while causing severe necrosis in the edible storage roots and to the stems that are used to produce the next crop.
Root necrosis, which can remain unnoticed until harvest, has a substantial impact on families that are dependent on the crop. Furthermore, stem cuttings produced from infected plants grow poorly or not at all, increasing chances that farmers will abandon the cultivation of cassava in severely affected regions, such as around Lake Victoria.
The enhanced cassava cultivars created by the VIRCA project will be readily available to farmers in the same way traditional cassava is being offered today and will have no royalty fees. This means farmers will be able to freely multiply, save and share their planting materials.
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