Status of Cassava (Manihot Esculenta Crantz) in Côte d’Ivoire: From Production to Consumption and Evaluation of Technology Adoption

The current state of cassava production and technology level as well as commercialization and consumption aspects were studied in Côte d’Ivoire. The study involved a sample of 570 actors of the value chain randomly selected in three (3) agro ecological regions (south, west and centre). Using a baseline survey questionnaire, 150 producers, 195 transformers and 195 consumers were interviewed. Results showed that farmers and consumers households are in majority led by men (80 and 61%) while transformers households are led by women (81%). Concerning the level of adoption of cassava technologies, it was found that about 35% of cassava growers are aware about the new cassava varieties and more than 80% agreed to use them. The analysis performed in agro ecological regions revealed that traditional varieties are preferred (40 % to 90 %) to improved varieties. Improved varieties, Bocou 1 (10.67%), TMS4 (2)1425 (0.67%) and Bocou 2 (0.67%) are less preferred for cultivation in spite of high yields, food processing or taste qualities, respectively mentioned by farmers. More than 50 % of farmers agreed to adopt the Rapid Seed Multiplication technique. Contrary to the localities of Man (West) and Bonoua (South) where pounded cassava is more consumed (89.29% and 66%), dehydrated cassava (Attieke) food is the most consumed in other localities surveyed. In spite of the high yield of improved varieties and the desire of cassava growers to adopt new cassava technologies, research and extension services should be reinforced taking into account agro ecological specificities of production, commercialization and consumption

Influence de l’âge des explants primaires sur la régénération des vitroplants de deux espèces d’ignames en côte d’ivoire: Dioscorea alata et Dioscorea cayenensis-rotundata (Dioscoreacea)

Objectif: En Côte d’Ivoire la production annuelle de Dioscorea spp est insuffisante à cause de la conservation des tubercules qui réduisent fortement les rendements des tubercule-semences. Il s’avère nécessaire de conserver tous les cultivars d’igname sous forme de vitroplant. Cette étude vise à évaluer l’effet du milieu de culture, de la désinfection et du type d’explants primaires sur la régénération et la conservation in vitro.Méthodologie et résultats: Les explants primaires prélevés sur les tiges âgées de 14, 21, 35 et 60 jours ont été désinfectés et mis en culture sur deux milieux de culture MS et MS modifié. Les explants primaires issus des tiges de 14 et 21 jours ont permis d’obtenir 99 à 100 % de vitroplants sains, 100 % de régénération au bout de 2 à 4 jours dans le milieu MS modifié avec en moyenne 3,82 à 5,14 noeuds et 1 à 2 tiges au bout de 60 jours. Tandis que ceux de 35 et 60 jours ont donné 35 à 74 %.de vitroplants sains, 1 à 4 noeuds et 1 à 2 tiges. Le milieu MS modifié et Les explants primaires issus des tiges de 14 et 21 jours permettant de régénérer les vitroplants au bout de 3 à 4 jours en moyenne ont été retenus.Conclusions et application des résultats: La conservation de toutes les variétés d’igname de la Côte d’Ivoire sous forme de vitroplants par la technique de régénération de tiges aériennes in vitro nécessite la satisfaction de certaines conditions. Ainsi pour la régénération de tous les cultivars les explants primaires prélevés sur les tiges âgées de 14 et 21 jours et le milieu de culture MS modifié ont été meilleurs. Tous les cultivars dans le milieu MS modifié ont été régénérés en moins d’une semaine et les vitroplants sains ont eu une bonne croissance offrant beaucoup de noeuds qui ont servi d’explants secondaires. La présente étude indique les  possibilités de production à grande échelle de semences des variétés d’igname pour répondre aux impératifs de sauvegarder et d’enrichir les ressources génétiques de l’igname en Côte d’Ivoire.Mots clés: Igname, explants primaires, cultivars, régénération, vitroplants, milieu de culture, âge, Côte d’IvoireEnglish Title: Influence of age to primary explants on the regeneration of vitroplant of two yam species in Côte d’Ivoire: Dioscorea alata and Dioscorea cayenensis-rotundata (Dioscoreacea)English AbstractObjectives: The annual production of Dioscorea spp in Côte d'Ivoire is insufficient because of the conservation of tubers, which greatly reduce the tuber yields. It is necessary to keep all of yam cultivars as vitroplant. This study aims to evaluate the effect of the culture medium, disinfection and type of primary explants on regeneration and in vitro conservation.Methodology and Results: Primary explants taken on older stems 14, 21, 35 and 60 days were disinfected and cultured on MS culture media and modified MS media. Primary explants from the stems of 14 and 21 days have resulted in 99 to 100% of healthy vitroplants, 100% of regeneration after 2 to 4 days in MS medium amended with an average of 3 to 5 nodes and 1 to 2 stems after 60 days. While those of 35 and 60 days gave 35-74% healthy vitroplants, from 1 to 4 nodes and 1 to 2 stems. The modified MS medium and primary explants from stems 14 and 21 days to regenerate the vitroplants after 3 to 4 days on average were selected.Conclusions and application of findings: The conservation of all varieties of yam from Côte d'Ivoire as vitroplants by aerial stems regeneration technique requires the satisfaction of certain conditions.So for the regeneration of all cultivars primary explants taken on older stems of 14 and 21 days and the modified MS culture medium were better. All cultivars in the modified MS medium were regenerated in less than a week and healthy vitroplants had good growth with many knots that served as secondary explants. This study shows the large-scale possibilities of seeds production for yam varieties to meet the requirements to safeguard and enrich the genetic resources of yams in Côte d'Ivoire.Keywords: yam, primary explants, cultivars, regeneration, vitroplants, culture medium, age, Côte d'Ivoir

Effect of water stress induced by polyethylene glycol 6000 on the somatic embryos conversion into whole plantlets in cocoa (Theobroma cacao L.)

Rainfall scarcity due to climate change is a major constraint that limits cocoa productivity in Côte d'Ivoire. This work aims to regenerate cocoa plants tolerant to water stress using in vitro methods. Staminode and petal explants of the genotypes C1, C9, C14, C15, C16, C18 and C20 were used to produce somatic embryos through two methods. Firstly, somatic embryos were induced under stressfull conditions on media containing different concentrations of polyethylene glycol (PEG) 6000 (0; 25; 50; 75; 100 and 125 g/l) and secondly; under non-stressed conditions. Somatic embryos were placed on a conversion medium in the same stress condition. The number of regenerants decreased with the increase in the concentration of PEG with all genotypes. Only genotypes C1 and C15 regenerated plantlets under water stress conditions. The sensitive genotypes C9, C14, C16, C18 and C20 have not developed plantlets on media containing PEG. The plantlets produced under water deficit conditions exhibited a reduction in stem length and leaves number and an increase in length or offset of the high number of roots. The survival rate of regenerants during acclimatization was higher on the sandsubstrate. The selected genotypes could be used in an improvement program of cocoa production.Keywords: Climate change; plant regeneration; genotype; tolerance; drought; in vitr

Influence of plant growth regulators on somatic embryogenesis induction from inner teguments of rubber (Hevea brasiliensis) seeds

Generating somatic embryos from the inner teguments of hevea seeds is difficult. Like other ligneous plants, the rubber-tree is generally considered to be recalcitrant with regard to somatic embryogenesis. In this study, the ability of callus from inner integument explants to develop embryogenic callus lines was highlighted. Combination of 2,4-dichlorophenoxyacetic acid (2,4-D/KT) (9 μM/3.375 μM) revealed the positive effect of the 2,4-D on callogenesis and somatic embryogenesis from the inner integument of the seed of immature fruit. The rate of embryogenic calli of about 50% obtained, suggested that 2,4-D has a similar effect as 3,4-dichlorophenoxy acetic acid (3,4-D). So, although 2,4-D is rarely used as a hormone in biotechnology of rubber, its positive influence on callus induction and somatic embryo development shows that it is an alternative to 3,4-D which is commonly used. Optimal combinations of 2,4-D/thidiazuron (TDZ) (9 μM/34.2 nM) produced abnormal embryos at lower rates (approximately 5%) than the optimal combination of 2,4-D/KT.Keywords: Callus, culture medium, Hevea brasiliensis, hormones, rubber-tree, somatic embryogenesisAfrican Journal of Biotechnology Vol. 12(16), pp. 1972-197

Callogenesis and Somatic embryogenesis induction in Hevea brasiliensis: effects of fruit shelf-life and carbon source

An experiment was conducted to study the effect of the fruit shelf-life and the concentrations of carbon source on somatic embryogenesis via callogenesis of Hevea brasiliensis. Fruits harvested were stored at 15°C during 1, 5, 7, 12 and 15 days and the inner integuments obtained from seed were used as explants. The experiments were performed under carbon source treatments with three concentrations for glucose and five concentrations for sucrose. Under these conditions, the percentage of  explants forming calli was better during the first week of fruit  preservation regardless of the carbon source but at high concentration. However, beyond 7 days of fruits shelf-life, sucrose is best to induce callus unlike glucose but with high concentration. The best rate of embryogenic calli was also obtained with sucrose. The percentages of callogenic explants and embryogenic calli have decreased sharply with the shelf-life of fruit at 15°C. So, to maintain an embryogenic potential of explants in situations of long-term conservation of fruits, sucrose can be used at 234 mM of concentration or default at 111 mM sucrose. These sucrose concentrations are conducive to induce embryogenic calli with  explants coming to rubber fruits after a long time of preservation

Emergence of begomoviruses and DNA satellites associated with weeds and intercrops: a potential threat to sustainable production of cassava in Côte d’Ivoire

Cassava (Manihot esculenta Crantz) plays a significant role in the livelihoods of people in Africa, particularly in Côte d’Ivoire. However, its production is threatened by begomoviruses which cause huge yield losses. Some weeds and food crops intercropped with cassava act as reservoirs, thereby facilitating the sustenance and propagation of Cassava mosaic begomoviruses (CMBs), along with other begomoviruses. To effectively manage these diseases, it is imperative to enhance our understanding of the various hosts of cassava viruses in Côte d’Ivoire. Thus, a comprehensive nationwide survey was conducted in 2017 in cassava fields across Côte d’Ivoire, and molecular analyses were performed on the samples collected. The results obtained from this survey indicated that 65 plant species belonging to 31 families were potential alternative hosts for CMBs in Côte d’Ivoire. The molecular analyses revealed that four species, Capsicum annuum, Solanum melongena, Centrosema pubescens, and Asystasia gangetica exhibited differential affinities for both African cassava mosaic virus and East African cassava mosaic Cameroon virus. Additionally, other begomoviruses and new alphasatellites were identified. Soybean chlorotic blotch virus was isolated from C. pubescens while West African Asystasia virus 1, West African Asystasia virus 2, and a new Asystasia yellow mosaic alphasatellite were isolated from A. gangetica which appears to be a plant species that could favor the emergence of new viral species harmful to cassava cultivation. This study offers insights that will inform the development of more effective control methods for sustainable cassava production in Côte d’Ivoire

Induction of somatic embryos of recalcitrant genotypes of Theobroma cacao L.

Objective: In cocoa tree (Theobroma cacao L.), some elite genotypes have shown, in standard study conditions, an absence or a very weak response to induction of somatic embryos. This is the case of the original C8  genotype Trinidad. This study aims to improve the production of somatic embryos in this genotypeMethodology and results: To do this, staminodes and petals excised from immature buds of genotypes C1, C8 and C14 were used. Genotypes C1 and C14 are embryogenic under standard conditions. These floral explants were cultured on induction media differing by the type and concentration of auxins. Callus induction obtained in the three studied genotypes ranged from 80% to 90% with the petal explants and from 70% to 80% with the staminodes regardless of the type and concentration of auxins. Transfer of callogenic explants to DKW (Driver & Kuniyuki, 1984) medium  supplemented with sucrose and glucose allowed the induction of somatic embryos at mean rates varying from 5% to 20% after only 84 days with petal explants and media supplemented with 2,4-dichlorophenoxyacetic acid (2,4-D) and 2, 4, 5-trichlorophenoxyacetic acid (2,4,5-T). No induction of somatic embryos was observed on the control medium with the C1, C8 and C14 genotypes. The C1 genotype induced somatic embryos in the presence of all concentrations of auxins. The highest rate of embryogenic callus and somatic embryo induction was obtained with 18 μM of 2, 4, 5-T in all C1 genotypes (39.29 ± 0.28; 17.98 ± 0.10), C8 (36.29% ± 0.26 and 15.01 ± 0.07) and C14 (33.92% ± 0.26 and 14.50 ± 0.16). The 2, 4, 5-trichlorophenoxyacetic acid (2, 4, 5-T). at 18 μM is the most appropriate auxin to remove recalcitrance in cocoa genotype C8. The use of higher 18 μM concentrations of 2, 4, 5-trichlorophenoxyacetic acid (2, 4, 5-T). and its application to other recalcitrant genotypes could confirm its beneficial effect on the removal of recalcitrance to somatic embryogenesis in cocoa.Conclusion and application of results: 18 μM concentration of 2, 4, 5-trichlorophenoxyacetic acid (2, 4, 5-T) gave the best percentage of embryogenic explants and the highest average number of embryos in the three genotypes  tested. Therefore, this protocol using 18 μM of 2, 4, 5-trichlorophenoxyacetic acid (2, 4, 5-T) could be used to  overcome  recalcitrance to somatic embryogenesis in cocoa.Keywords: recalcitrant, cocoa, auxins, somatic embryogenesi