Introduction
African cassava mosaic virus (ACMV), East African cassava mosaic virus (EACMV), and South African cassava mosaic virus (SACMV) are distinct species of circular single-stranded DNA viruses that are whitefly-transmitted and primarily infect cassava plants. These have thus far only been reported from Africa; related species of viruses (Indian cassava mosaic virus, ICMV) are found in India and neighbouring islands (Sri Lankan cassava mosaic virus, SLCMV), though cassava is cultivated in Latin America as well as South East Asia. Nine species of cassava-infecting geminiviruses have been identified between Africa and India based on genomic sequencing and phylogenetic analysis. This number will probably grow due to a high rate of natural transformation associated with CMV
The viruses are members of the Family Geminiviridae and the Genus Begomovirus. The first report of cassava mosaic disease (CMD) was from East Africa in 1894. Since then, epidemics have occurred throughout the African continent resulting in great economic loss and devastating famine. In 1971 a resistant line of cassava, the predominant host of this plant pathogenic virus, was established and used by the International Institute of Tropical Agriculture in Nigeria. This resistance worked as an effective control for many years. However, in the late 20th century, a more virulent virus broke out in Uganda and quickly spread to East and Central Africa. This highly virulent virus was later discovered to be a chimaera of two distinct begomovirus species.
Currently, CMD is managed through phytosantitation practices as well as the use of conventional resistance breeding. Additionally, vector management and cross-protection help to minimize transmission and symptom development. Though management practices are useful, the viruses’ high rate of recombination and co-infection capabilities have caused CMD to be one of the most detrimental diseases affecting food supply in Africa.
Read more about this topic: Cassava Mosaic Virus
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