Estimation of Genetic Diversity and Number of Unique Genotypes of Cassava Germplasm from Burkina Faso Using Microsatellite Markers.

Genetic diversity is very important in crop improvement. This study was carried out to assess the genetic diversity and the number of unique multilocus genotypes (MLGs) in a cassava collection in Burkina Faso. To achieve this objective, 130 cassava accessions were genotyped using 32 simple sequence repeat (SSR) markers. The results revealed that among these markers, twelve (12) were highly informative, with polymorphic information content (PIC) values greater than 0.50; twelve (12) were moderately informative, with PIC values ranging between 0.25 and 0.50; and eight (8) were not very informative, with PIC values lower than 0.25. A moderate level of genetic diversity was found for the population, indicated by the average expected heterozygosity (0.45) and the observed heterozygosity (0.48). About 83.8% of unique multilocus genotypes were found in the cassava collection, indicating that SSR markers seem to be most appropriate for MLG identification. Population structure analysis based on hierarchical clustering identified two subpopulations and the Bayesian approach suggested five clusters. Additionally, discriminant analysis of principal components (DAPC) separated the cassava accessions into 13 subpopulations. A comparison of these results and those of a previous study using single nucleotide polymorphisms (SNP) suggests that each type of marker can be used to assess the genetic structure of cassava grown in Burkina Faso.

Epidemiological assessment of cassava mosaic disease in Burkina Faso.

Surveys were conducted in 2016 and 2017 across the main cassava-growing regions of Burkina Faso to assess the status of cassava mosaic disease (CMD) and to determine the virus strains causing the disease, using field observation and phylogenetic analysis. CMD incidence varied between regions and across years but was lowest in Hauts-Bassins (6.0%, 2016 and 5.4%, 2017) and highest in Centre-Sud (18.5%, 2016) and in Boucle du Mouhoun (51.7%, 2017). The lowest CMD severity was found in Est region (2.0) for both years and the highest in Sud-Ouest region (3.3, 2016) and Centre-Sud region (2.8, 2017). The CMD infection was primarily associated with contaminated cuttings in all regions except in Hauts-Bassins, where whitefly-borne infection was higher than cuttings-borne infection in 2016. PCR screening of 687 samples coupled with sequence analysis revealed the presence of African cassava mosaic-like (ACMV-like) viruses and East African cassava mosaic-like (EACMV-like) viruses as single infections at 79.5% and 1.1%, respectively. Co-infections of ACMV-like and EACMV-like viruses were detected in 19.4% of the tested samples. In addition, 86.7% of the samples positive for EACMV-like virus were found to be positive for East African cassava mosaic Cameroon virus (EACMCMV). Phylogenetic analysis revealed the segregation of cassava mosaic geminiviruses (CMGs) from Burkina Faso into three clades specific to ACMV, African cassava mosaic Burkina Faso virus (ACMBFV), and EACMCMV, confirming the presence of these viruses. The results of this study show that EACMCMV occurrence may be more prevalent in Burkina Faso than previously thought.

Characterization of virus species associated with sweetpotato virus diseases in Burkina Faso.

Sweetpotato (Ipomoea batatas) production in sub-Saharan Africa is severely affected by viral diseases caused by several interacting viruses, including sweet potato feathery mottle virus (SPFMV), sweet potato chlorotic stunt virus (SPCSV), and sweet potato leaf curl virus (SPLCV). However, the aetiology of viral symptoms on sweetpotato is rarely established in most countries in Africa. Here, we aimed to investigate and characterize the incidence of sweetpotato viruses in Burkina Faso. We performed a countrywide survey in 18 districts of Burkina Faso and collected 600 plants, with and without symptoms, from 80 fields. Viral strains were identified using nitrocellulose membrane-ELISA, PCR, and reverse transcription-PCR. Three scions from each of 50 selected plants with symptoms were grafted to healthy Ipomoea setosa and then serological and molecular tests were performed on the 150 recorded samples. Three viruses were detected: 24% of samples were positive for SPFMV, 18% for SPLCV, and 2% for SPCSV. Across all diagnostic tests, 40% of all plant samples were virus-negative. Coinfections were found in 16% of samples. Partial sequences were obtained, including 13 that matched SPFMV, one that matched SPLCV, and one that matched SPCSV. All identified SPFMV isolates belonged to either phylogroup B or A-II. The SPCSV-positive isolates had 98% gene sequence homology with SPCSV-West Africa for the coat protein. Begomovirus-positive isolates clustered with SPLCV-United States. This first study of sweetpotato viral diseases in Burkina Faso indicates widespread occurrence and suggests a need for further epidemiological investigations, breeding programmes focused on virus-resistant varieties, and improved farming practices to control disease spread.

Origins, production, and utilization of cassava in Burkina Faso, a contribution of a neglected crop to household food security.

Cassava (Manihot esculenta Crantz) is a food plant introduced in Africa from America by the Portuguese in 1558. The objective of this study is to establish cassava origins, production, and utilization in Burkina Faso. The investigation was carried out in the regions of Center West, Cascades, Boucle du Mouhoun, Hauts Bassins, South West, and Center East of Burkina Faso. Eighteen cassava processing units and 226 farmers in 57 communities from the selected regions have been involved in the survey. The investigation showed that cassava was introduced to Burkina Faso, former Upper Volta from the costal countries, Gold Coast (now Ghana), by both local traders and the Roman Catholic White missionaries. This happened between the second half of the 19th century and the beginning of the 20th century. The main variety introduced was Banfti. Some improved varieties like V5 (94/0270), Banké (V2), 68.61, 30572, KTMA developed by research are now available and used by farmers along with the traditional varieties like manchien, santidougou, tchinda yaar, léo. The cases of intoxication evoked by some farmers are evidence that some of those varieties may have a high level of cyanohydric acid content. Cassava is available all the year throughout the country. But the top of cassava production is reached in July. Most of the small-scale farmers (98%) grow cassava both for household use and as income generator. About 83.92% of cassava farmers have less than 10 tons as annual production and only 1.72% of them can produce more than 100 tons. The main food products based on cassava found in communities are raw roots, boiled roots, roasted roots, tô, attiéké, tapioca, ragout, beignets, boiled leaves, soup (with leaves), cassava juice, etc. And the main cassava-processed products in the processing units are attiéké, gari, tapioca, and flour. Cassava contributes greatly to household food security during food shortage period. It sustains families for weeks as food and is also exchanged with other foods or sold to buy food or meet household needs.