Occurrence of East African cassava mosaic virus‐Uganda (EACMV‐UG) in Burkina Faso

Abstract

) is a major staple food crop cultivatedthroughout Africa, and is affected most severely by cassava mosaic disease(CMD) occurring at high incidence throughout the continent. CMD iscaused by cassava mosaic geminiviruses (CMGs) belonging to the genusBegomovirus (family Geminiviridae). The complex of CMGs includeseven African species; the three main species are: African cassava mosaicvirus (ACMV), East African cassava mosaic virus (EACMV) and SouthAfrican cassava mosaic virus (SACMV) (Bull et al., 2006). In Uganda, anextremely severe epidemic of CMD has developed since the 1990s and hasprogressed since then in Uganda’s neighbouring countries and CentralAfrica. The severe CMD phenotype is caused by the synergistic interactionbetween ACMV and a distinct recombinant strain EACMV-UG, commonlyknown as the Uganda variant. CMD is reported to be widespread inBurkina Faso (Konate et al., 1995), but the molecular features of the causalagent have never been investigated.In August/September 2008, leaves were collected from cultivars of localcassava presenting moderate to severe CMD symptoms from the centralregion around Ouagadougou. Ten leaf samples were tested and found tobe positive for the presence of begomoviruses by PCR, using degenerateprimers VD360 and CD1266 (Delatte et al., 2005). For two of thesesamples, complete DNA-A genomes were cloned using the Phi29 DNApolymerase-based rolling circle amplification strategy (Inoue-Nagataet al., 2004) and sequenced by Macrogen Inc. (Korea). One sequence(EMBL-GenBank-DDBJ Accession No. FM877473) showed 97% highestnucleotide identity with ACMV-[Ivory Coast:1999] (AF259894) andACMV-[Nigeria:Ogoroco:1990] (AJ427910). The second sequence(FM877474) showed 98% nucleotide identity with EACMV-UG[Uganda:Severe2:1997] (AF126806).This is the first report of the Uganda variant in West Africa. These resultsshow that both species ACMV and EACMV-UG affect cassava plantingsin Burkina Faso, and suggest a potential risk of the occurrence of a severeepidemic of CMD as in East Africa.AcknowledgementsThis research was funded by the following institutions: CRSBAN/UFR-SVT(University of Ouagadougou), INERA (CNRST, Burkina Faso), ConseilRegional de La Reunion, CIRAD, European Union (FEDER) and GISCentre de recherche et de veille sanitaire sur les maladies emergentes dansl’Ocean Indien (N°PRAO/AIRD/CRVOI/08/03).ReferencesBull SE, Briddon RW, Sserubombwe WS, Ngugi K, Markham PG, Stanley J, 2006. Genetic diversity and phylogeography of cassava mosaic viruses in Kenya.