Data/hora: 25/05/2024 02:55:05

Biblioteca(s): | Embrapa Mandioca e Fruticultura.
Data corrente: | 16/04/2004
Data da última atualização: | 16/04/2004
Autoria: | FAUQUET, C. M.; FONDONG, V.; PITA, J.; TORES-JEREZ, I.; OTIM-NAPE, W. G.; OGWAL, S.; SANGARE, A.; REY, C.; BROWN, J. K.; BEACHY, R. N.
Título: | Etiology of the cassava mosaic disease in Africa reveals increasing complexity and diversity.
Ano de publicação: | 1998
Fonte/Imprenta: | Revista Brasileira de Mandioca, Salvador, v. 17, p. 39, nov., 1998., Suplemento.
Idioma: | Inglês
Conteúdo: | Abstract: Since the beginning of this century cassava mosaic disease has been reported in all the African countries growing cassava. Symptoms vary somewhat from one country to the nex but always show mosaic, leaf curl and a significant reduction in yield. The presence of a dramatic new virus epidemic in cassava has caused increasing concern in Uganda since 1986. The new disease induces very severe symptoms, often resulting in total yield loss and failure of cutting establishment from infected stems. Two virus species have been isolated both from these plants and the whitefly vectors; the African cassava mosaic virus (ACMV) and the East African cassava mosaic virus (EACMV). Infection with the former is correlated with mild symptoms whilst presence of the latter causes severe symptoms in the crop. Sequence comparison of the EACMV virus isolate with other cassava viruses revealed that it is a recombinant between EACMV and ACMV. A large sampling of infected cassava plants from Uganda, allowed us to identify mild and severe strains of both irrespective of the symptoms induced on cassava, thereby indicating the absence of correlation between recombination and symptom severety. Comparison of mitochondria DNA sequences from whiteflies collected in each ecological situation indicated that a distinct population of B. tabaci, presently of unknown origin, is correlated with the presence of  the severe symptoms and therefore with EACMV/UG. In west Africa the variety of symptoms seen on cassava are difficult to the cassava genotype or to the virus isolate. The two virus species; ACMV and EACMV, have also been isolated in Camerron and in Ivory Coast. A range of symptoms have been recorded in cassava and can now be reproduced on artificial hosts from crude sap and from infectious clones. Studies have revealed that, while ACMV is very similar throughout Africa, EACMV reveals the presence of different recombined fragments of unknown origin. The importance and relevance of these findings relative to symptoms on cassava and the epidemic in Uganda will be discussed.
Categoria do assunto: | --
Registro original: | Embrapa Mandioca e Fruticultura (CNPMF)
Exemplares: | CNPMF - (20982-1) - ADD - AP - -- - 633.68205 -  -  - DIS