A global alliance declaring war on cassava viruses in Africa

Abstract

The importance of cassava as a food security crop in Africa and the world Cassava, originally from South America, is the fourth most important source of calories in the developing world after the cereal crops wheat, maize, and rice. Worldwide, it feeds an estimated 700 million people directly or indirectly. Cassava production has increased steadily for the last 50 years, with 242 MT harvested in 2012. The increase is likely to continue as farmers in more than 105 countries come to recognize the crop's advantages. A semi-perennial root crop, cassava can stay in the ground for up to 3 years. This makes it an excellent food security crop: when all other crops have been exhausted, cassava roots can still be harvested. It is naturally drought resistant and resilient to climatic changes, high temperatures, and poor soils, and in addition, cassava responds extremely well to high CO 2 concentrations, making it a very important crop for the 21st century. Africa alone accounts for more than 55 % of the world's production, and cassava is the first food crop in fresh tonnage before maize and plantain in sub-Saharan Africa. Cassava is also an important source of income, especially for women in sub-Saharan Africa (SSA). Furthermore, cassava is the second most important source of starch in the world. Cassava is thus a highly valuable crop for the world today and in the future. It is critical that it should not be compromised by viral diseases.

Crop losses in Brazilian cassava varieties induced by the Cassava common mosaic virus

“…Cassava (Manihot esculenta Crantz) is the fourthmost important source of calories worldwide, behind only wheat, corn, and rice (Legg et al, 2014a). Currently, about 20 million hectares are planted with cassava, with a total production of 260 million tons distributed over approximately 80 countries.…”

Cassava brown streak disease: a threat to food security in Africa

“…Up to 100-fold increases in B. tabaci abundance have been recorded in CMD pandemic-affected regions of East and Central Africa, including Uganda, western Kenya, north-western Tanzania, Rwanda, Burundi and eastern DRC (Legg et al, 2006). Evidence has been presented for the association of specific genotypes of B. tabaci with the cassava virus pandemics of East and Central Africa (Legg et al, 2002(Legg et al, , 2014b, although it has also been hypothesized that B. tabaci population increases are a consequence of synergistic interactions with CMD-infected cassava host plants (Colvin et al, 2006). Whichever is the case, the upsurge in B. tabaci population is incontrovertible and appears to be the key driver of the new mid-altitude outbreaks of CBSD (Legg et al, , 2014b.…”

“…Evidence has been presented for the association of specific genotypes of B. tabaci with the cassava virus pandemics of East and Central Africa (Legg et al, 2002(Legg et al, , 2014b, although it has also been hypothesized that B. tabaci population increases are a consequence of synergistic interactions with CMD-infected cassava host plants (Colvin et al, 2006). Whichever is the case, the upsurge in B. tabaci population is incontrovertible and appears to be the key driver of the new mid-altitude outbreaks of CBSD (Legg et al, , 2014b. These recent changes in the dynamics and distribution of CBSD mean that there is great current concern about the threat of further westward spread within Africa towards Nigeria (Legg et al, 2014a), which is currently the world's largest producer of cassava (FAOSTAT, 2014).…”

“…In addition, the importance has been emphasized for national and subregional-level quarantine authorities to enforce effective controls on intra-and inter-continental movements of cassava germplasm in order to ensure that CBSD does not spread beyond its currently confined distribution in eastern and southern Africa (Legg et al, 2014b).…”

Genetic diversity and population structure of traditional sweet cassava accessions from Southern of Minas Gerais State, Brazil, using microsatellite markers

“…Cassava (Manihot esculenta Crantz), originally from the Neotropical region (Olsen and Schaal, 2001) is a perennial plant of the dicotyledonous class (Euphorbiacea family), which plays a considerable role as the fourth most cultivated food culture in the world (Nassar, 2000;Olsen and Schaal, 2001;Perera et al, 2014;Legg et (Nassar, 2000;ElSharkawy, 2004).…”