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

Etat Des Lieux Et Gestion Des Semences Des Principales Céréales Cultivées Au Nord De La Côte d’Ivoire

The survey aims at assessing current managing status of organizations involves in the conservation of local genetic diversity of rice, maize, sorghum and pearl millet in seedbanks located in northern Côte d’Ivoire. An investigation was conducted with 100 respondents in charge of cereal seedbanks managing from Ferkessedougou and Ouangolodougou areas. The results at regional scale revealed two co-existing informal and formal systems for seedbanks management in these areas. The farmers’ seedbanks system or informal system was the main source of cereal seed supply for farmers and more important than the national or formal seedbank system. Only, farmers’ seedbanks of two crops, rice and maize were found in visited localities. The management of these farmers’ seedbanks was enabled by associations or cooperatives gathering more men (78.27%) than women (21.73%). Ninety percent (90%) of respondents were identified as saving 1 to 3 traditional varieties of cereal in these seedbanks managed by farmers in the studied region. The reveled difficulties in the farmers’ seedbanks management appeared mainly as informally organized seed system that must be a complementary approach to formal system or national seed system for genetic diversity preservation of local cereal varieties and also as a distribution channel of improved cereal varieties

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

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

The role of community seed banks in achieving farmers’ rights

The core objectives of the Convention on Biological Diversity and the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA) are the conservation and sustainable use of plant genetic resources. The ITPGRFA links these goals explicitly to farmers’ rights. Although farmers’ rights have been debated intensely at international level, their effective implementation at national level remains a major challenge. Community seed banks are good examples of effective implementation of those rights, but have received little attention in scientific literature and policy circles. Case studies in this article from Bangladesh, Côte d’Ivoire, India and Zimbabwe illustrate how this knowledge gap can be filled