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  • Author or Editor: Colombe Dadjo x
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Theobroma cacao L. (cacao) is a major tropical crop, grown for its oil-rich seed, which is used in the manufacture of chocolate, its derivatives, and cosmetics. Cacao is cultivated mainly by smallholders and represents a significant export commodity for some developing countries such as Côte d’Ivoire. It is conventionally propagated by seeds, grafting, and cuttings. Somatic embryogenesis offers an alternative method for propagation where large-scale production of planting materials is possible. In the current study, the effect of different concentrations of 2, 4-dichlorophenoxyacetic acid (2, 4-D) and kinetin on induction of somatic embryogenesis and plantlet regeneration in two cocoa clones (coded as C1 and C14) were evaluated. Flowers were collected early in the morning, sterilized, explants excised and cultured on Driver, and Kuniyuki Walnut (DKW) media supplemented with different concentrations of 2, 4-D (9, 10, and 20 µM) and kinetin (0.5, 1, 2.5, 5, 10, and 25 µM) in separate experiments. The frequently used media in somatic embryogenesis of cacao [DKW supplemented with 0.022 µM thidiazuron (TDZ) and 9 µM 2, 4-D] was used as a control. The results of the study showed that explants cultured on media supplemented with 10 µM 2, 4-D and 5 µM kinetin produced the highest (28.0 ± 1.1) mean number of embryos/explant in C1 and this was a 9-fold increase in the number of embryos compared with the control. Explants cultured on media supplemented with 10 µM 2, 4-D and 2.5 µM kinetin produced the highest (7.0 ± 4.0) mean number of embryos/explant in C14 whereas the explants cultured on media supplemented with 20 µM 2, 4-D and 2.5 µM kinetin gave the highest (22.0 ± 1.7) mean number of embryos in clone C1 and C14. The regenerated embryos were germinated and successfully weaned in the green house with a survival rate of 70% being recorded. The paper describes an improved protocol compared with previous work in terms of embryo recovery and survival rate of the elite clones of cocoa through somatic embryogenesis. The results of the current study confirm that somatic embryogenesis of cacao clones is genotype dependent.

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Erythrina abyssinica (E. abyssinica) is a multipurpose tree and a well-known medicinal plant which is conventionally propagated mainly by seeds. This method may produce a high degree of genetic variability and consequently decrease the medicinal value of the plant. Besides, the seeds have low germination rate and propagation is restricted to rainy season. Hence, there is need to develop a propagation protocol which produces a uniform plants and one which is not restricted to seasons. The objective of this study was to establish an in vitro propagation protocol for the multiplication of E. abyssinica. Seeds were sterilized and germinated in vitro to get sterile starting explants. Sterilization of the seeds was evaluated using different concentrations of a commercial bleach (JIK) ranging from 10%, 20% to 30% for 25 minutes. Kinetin (2.25, 4.50, 6.75, and 9.0 mg/L), and benzylaminopurine (BAP; 2.15, 4.30, 6.46, and 8.61 mg/L) were evaluated in separate experiments for their effect to induce microshoots from nodal explants. Rooting of the microshoot was carried out using half strength Murashige and Skoog (MS) media supplemented with indolebutyric acid (IBA) (0.20, 0.51, and 1.02 mg/L). Statistical analysis software (SAS) package was used to perform analysis of variance on the data to test the significance of the difference between treatments. The result of the sterilization experiment indicated that 10% JIK gave the highest percentage (55%) of clean seeds. Benzylaminopurine evaluated at 8.61 mg/L gave the highest mean number of microshoots (6.80 ± 1.24) after 28 days. On the other hand, IBA evaluated at 0.51mg/L gave the highest mean root length (6.00 ± 01.85 cm). The regenerated plants were acclimatized in the greenhouse and 65% survival rate was recorded after one month. With the increasing worldwide demand for medicinal plants as an alternative to prescription drugs, ex situ, in situ conservation programs and true to type mass propagation of E. abyssinica could benefit from the findings of this study. This is the first report on micropropagation of E. abyssinica.

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