Molecular Characterization of Cassava Mosaic Viruses and Current Mosaic Disease Concern in Three Major Cassava Production Areas in Côte D’ivoire

Abstract

Background and Objective: Since its introduction in Côte d'Ivoire in the 1980s, Cassava Mosaic Disease has so far continued to cause damage to cassava production in the country. This study aimed to characterize cassava mosaic diseaseʼs pathogens and emphasize current concerns in three major cassava-producing regions for better disease control. Materials and Methods: Two hundred cassava leaf samples comprising symptomatic infection and healthy characteristics from improved and traditional varieties were collected in the departments of Bouaké, Yamoussoukro and Daloa from 2019-2020 in rainy and dry seasons. These leaves were subjected to molecular analyses. Cassava Mosaic Diseaseʼs prevalence and severity were evaluated. All data were analyzed with software R, version 3.3.1. Results: Cassava Mosaic Disease overall phenotypic prevalence was 43.37% and almost equally distributed in all investigated departments. After the molecular diagnostic, the infection rate reached 77.7% for symptomatic plants and 34.28% for asymptomatic plants. The severity scores in traditional and improved varieties were S2, S3 and S4 but S2 were the most frequent. ACMV strains were the most detected while EACMV and co-infections showed the highest injury. Conclusion: The Cassava Mosaic Viruses largely present in all surveyed regions. Traditional varieties seem to be more resistant to infections and therefore require particular attention for virusesʼ control.

Gradual Emergence of East African cassava mosaic Cameroon virus in Cassava Farms in Côte d’Ivoire

“…Molecular analysis of cassava leaf samples collected from the fields in 2016, 2017, and 2020 confirmed the presence of ACMV and EACMCMV in Côte d'Ivoire, as previously reported by Pita et al [17] and Toualy et al [18]. ACMV was detected countrywide and was the most prevalent virus [19]. However, the rate of occurrence of single ACMV infections dropped from 2017 to 2020 and seems to be progressively replaced by the coinfection of ACMV and EACMCMV.…”

“…In Côte d'Ivoire, EACMCMV was first reported in 2001 [13], and it was always found to be associated with ACMV. The presence of these viruses was also documented later in cassava in Côte d'Ivoire by [18,19]. Despite these studies, knowledge of the epidemiology of cassava mosaic viruses in Côte d'Ivoire is still poor.…”

“…Dual or multiple members of the cassava begomovirus group can participate in mixed infections, typically characterized by severe symptoms [17]. Nationwide surveys conducted to date in West African countries have shown that three of the nine virus species described in Africa (ACMV, EACMV, and EACMCMV) are the viruses most commonly found in cassava fields [13,[18][19][20][21][22]. In Côte d'Ivoire, EACMCMV was first reported in 2001 [13], and it was always found to be associated with ACMV.…”