Abstract:Cassava mosaic geminiviruses (CMGs) are implicated in cassava mosaic disease (CMD), the main constraint to cassava production in Africa. Here, we report the complete nucleotide sequences of the DNA-A and DNA-B of a newly characterized CMG found infecting cassava in Madagascar, for which we propose the tentative name cassava mosaic Madagascar virus. With the exception of two recombinant regions that resembled a CMG, we determined that the non-recombinant part of the DNA-A component is distantly related to the o… Show more
“…1). Despite the recent isolation of a single CMMGV genome from the south-western part of the island [15], no additional isolates of this species were discovered here.Fig. 1Species composition and repartition map of the CMGs in Madagascar.…”
Section: Resultsmentioning
confidence: 99%
“…The information available in public sequence databases included only three complete CMG genome component sequences: the DNA-A component of a SACMV [GenBank:AJ422132] [35], and the DNA-A and DNA-B components of a novel recombinant begomovirus, CMMGV [15]. As part of this study, a total of 279 full DNA-A and 117 full DNA-B components were cloned and sequenced from 173 symptomatic Madagascan cassava leaves sampled during an epidemiological survey conducted between 2009 and 2011 [22] as well as 91 additional samples collected on the island between 2005 and 2008.…”
Section: Resultsmentioning
confidence: 99%
“…All known CMG species (Additional file 1: Figure S1), including African cassava mosaic virus (ACMV, [6, 7]), East African cassava mosaic virus (EACMV, [8]), East African cassava mosaic Cameroon virus (EACMCV, [9]), East African cassava mosaic Malawi virus (EACMMV, [10]), East African cassava mosaic Zanzibar Virus (EACMZV, [11]), South African cassava mosaic virus (SACMV, [12]), East African cassava mosaic Kenya virus (EACMKV, [13]), African cassava mosaic Burkina Faso virus (ACMBFV, [14]) and Cassava mosaic Madagascar virus (CMMGV, [15]), have genomes consisting of two components, called DNA-A and DNA-B, each comprising a 2.7 kb circular single-stranded DNA molecule [6]. All of these viruses are transmitted by Bemisia tabaci : a whitefly species complex consisting of several cryptic species [16].…”
Section: Introductionmentioning
confidence: 99%
“…Despite the importance of the disease, molecular and epidemiological data on the causal species were lacking until 2012 when a series of surveys carried out between 2009 and 2011 [15, 22] indicated the presence on the island of six of the nine known African CMG species: a higher degree of CMG diversity than has been detected in any other part of the world. Importantly, these studies also indicated both that the six Madagascan CMG species likely have at least partially overlapping geographical ranges, and that frequent co-infections containing two or more species also occur.…”
BackgroundCassava mosaic disease (CMD) in Madagascar is caused by a complex of at least six African cassava mosaic geminivirus (CMG) species. This provides a rare opportunity for a comparative study of the evolutionary and epidemiological dynamics of distinct pathogenic crop-infecting viral species that coexist within the same environment. The genetic and spatial structure of CMG populations in Madagascar was studied and Bayesian phylogeographic modelling was applied to infer the origins of Madagascan CMG populations within the epidemiological context of related populations situated on mainland Africa and other south western Indian Ocean (SWIO) islands.ResultsThe isolation and analysis of 279 DNA-A and 117 DNA-B sequences revealed the presence in Madagascar of four prevalent CMG species (South African cassava mosaic virus, SACMV; African cassava mosaic virus, ACMV; East African cassava mosaic Kenya virus, EACMKV; and East African cassava mosaic Cameroon virus, EACMCV), and of numerous CMG recombinants that have, to date, only ever been detected on this island. SACMV and ACMV, the two most prevalent viruses, displayed low degrees of genetic diversity and have most likely been introduced to the island only once. By contrast, EACMV-like CMG populations (consisting of East African cassava mosaic virus, EAMCKV, EACMCV and complex recombinants of these) were more diverse, more spatially structured, and displayed evidence of at least three independent introductions from mainland Africa. Although there were no statistically supported virus movement events between Madagascar and the other SWIO islands, at least one mainland African ACMV variant likely originated in Madagascar.ConclusionsOur study highlights both the complexity of CMD in Madagascar, and the distinct evolutionary and spatial dynamics of the different viral species that collectively are associated with this disease. Given that more distinct CMG species and recombinants have been found in Madagascar than any other similarly sized region of the world, the risks of recombinant CMG variants emerging on this island are likely to be higher than elsewhere. Evidence of an epidemiological link between Madagascan and mainland African CMGs suggests that the consequences of such emergence events could reach far beyond the shores of this island.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0749-2) contains supplementary material, which is available to authorized users.
“…1). Despite the recent isolation of a single CMMGV genome from the south-western part of the island [15], no additional isolates of this species were discovered here.Fig. 1Species composition and repartition map of the CMGs in Madagascar.…”
Section: Resultsmentioning
confidence: 99%
“…The information available in public sequence databases included only three complete CMG genome component sequences: the DNA-A component of a SACMV [GenBank:AJ422132] [35], and the DNA-A and DNA-B components of a novel recombinant begomovirus, CMMGV [15]. As part of this study, a total of 279 full DNA-A and 117 full DNA-B components were cloned and sequenced from 173 symptomatic Madagascan cassava leaves sampled during an epidemiological survey conducted between 2009 and 2011 [22] as well as 91 additional samples collected on the island between 2005 and 2008.…”
Section: Resultsmentioning
confidence: 99%
“…All known CMG species (Additional file 1: Figure S1), including African cassava mosaic virus (ACMV, [6, 7]), East African cassava mosaic virus (EACMV, [8]), East African cassava mosaic Cameroon virus (EACMCV, [9]), East African cassava mosaic Malawi virus (EACMMV, [10]), East African cassava mosaic Zanzibar Virus (EACMZV, [11]), South African cassava mosaic virus (SACMV, [12]), East African cassava mosaic Kenya virus (EACMKV, [13]), African cassava mosaic Burkina Faso virus (ACMBFV, [14]) and Cassava mosaic Madagascar virus (CMMGV, [15]), have genomes consisting of two components, called DNA-A and DNA-B, each comprising a 2.7 kb circular single-stranded DNA molecule [6]. All of these viruses are transmitted by Bemisia tabaci : a whitefly species complex consisting of several cryptic species [16].…”
Section: Introductionmentioning
confidence: 99%
“…Despite the importance of the disease, molecular and epidemiological data on the causal species were lacking until 2012 when a series of surveys carried out between 2009 and 2011 [15, 22] indicated the presence on the island of six of the nine known African CMG species: a higher degree of CMG diversity than has been detected in any other part of the world. Importantly, these studies also indicated both that the six Madagascan CMG species likely have at least partially overlapping geographical ranges, and that frequent co-infections containing two or more species also occur.…”
BackgroundCassava mosaic disease (CMD) in Madagascar is caused by a complex of at least six African cassava mosaic geminivirus (CMG) species. This provides a rare opportunity for a comparative study of the evolutionary and epidemiological dynamics of distinct pathogenic crop-infecting viral species that coexist within the same environment. The genetic and spatial structure of CMG populations in Madagascar was studied and Bayesian phylogeographic modelling was applied to infer the origins of Madagascan CMG populations within the epidemiological context of related populations situated on mainland Africa and other south western Indian Ocean (SWIO) islands.ResultsThe isolation and analysis of 279 DNA-A and 117 DNA-B sequences revealed the presence in Madagascar of four prevalent CMG species (South African cassava mosaic virus, SACMV; African cassava mosaic virus, ACMV; East African cassava mosaic Kenya virus, EACMKV; and East African cassava mosaic Cameroon virus, EACMCV), and of numerous CMG recombinants that have, to date, only ever been detected on this island. SACMV and ACMV, the two most prevalent viruses, displayed low degrees of genetic diversity and have most likely been introduced to the island only once. By contrast, EACMV-like CMG populations (consisting of East African cassava mosaic virus, EAMCKV, EACMCV and complex recombinants of these) were more diverse, more spatially structured, and displayed evidence of at least three independent introductions from mainland Africa. Although there were no statistically supported virus movement events between Madagascar and the other SWIO islands, at least one mainland African ACMV variant likely originated in Madagascar.ConclusionsOur study highlights both the complexity of CMD in Madagascar, and the distinct evolutionary and spatial dynamics of the different viral species that collectively are associated with this disease. Given that more distinct CMG species and recombinants have been found in Madagascar than any other similarly sized region of the world, the risks of recombinant CMG variants emerging on this island are likely to be higher than elsewhere. Evidence of an epidemiological link between Madagascan and mainland African CMGs suggests that the consequences of such emergence events could reach far beyond the shores of this island.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0749-2) contains supplementary material, which is available to authorized users.
“…Recently, two putative species have also been newly described: African cassava mosaic Burkina Faso virus (ACMBFV, [9]) and Cassava mosaic Madagascar virus (CMMGV, [10]).…”
BackgroundCassava (Manihot esculenta) is a major food source for over 200 million sub-Saharan Africans. Unfortunately, its cultivation is severely hampered by cassava mosaic disease (CMD). Caused by a complex of bipartite cassava mosaic geminiviruses (CMG) species (Family: Geminivirideae; Genus: Begomovirus) CMD has been widely described throughout Africa and it is apparent that CMG's are expanding their geographical distribution. Determining where and when CMG movements have occurred could help curtail its spread and reveal the ecological and anthropic factors associated with similar viral invasions. We applied Bayesian phylogeographic inference and recombination analyses to available and newly described CMG sequences to reconstruct a plausible history of CMG diversification and migration between Africa and South West Indian Ocean (SWIO) islands.ResultsThe isolation and analysis of 114 DNA-A and 41 DNA-B sequences demonstrated the presence of three CMG species circulating in the Comoros and Seychelles archipelagos (East African cassava mosaic virus, EACMV; East African cassava mosaic Kenya virus, EACMKV; and East African cassava mosaic Cameroon virus, EACMCV). Phylogeographic analyses suggest that CMG’s presence on these SWIO islands is probably the result of at least four independent introduction events from mainland Africa occurring between 1988 and 2009. Amongst the islands of the Comoros archipelago, two major migration pathways were inferred: One from Grande Comore to Mohéli and the second from Mayotte to Anjouan. While only two recombination events characteristic of SWIO islands isolates were identified, numerous re-assortments events were detected between EACMV and EACMKV, which seem to almost freely interchange their genome components.ConclusionsRapid and extensive virus spread within the SWIO islands was demonstrated for three CMG complex species. Strong evolutionary or ecological interaction between CMG species may explain both their propensity to exchange components and the absence of recombination with non-CMG begomoviruses. Our results suggest an important role of anthropic factors in CMGs spread as the principal axes of viral migration correspond with major routes of human movement and commercial trade. Finer-scale temporal analyses of CMGs to precisely scale the relative contributions of human and insect transmission to their movement dynamics will require further extensive sampling in the SWIO region.
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