The effect of plant growth regulators on callus and somatic embryogenesis induction in four Cocoa (Theobroma cacao) genotypes was studied. Flower explants were harvested early in the morning and cultured on Driver and Kuniyuki Walnut (DKW) medium supplemented with 1 mg·L−1 of five auxins type (2,4 dichlorophenoxyacetic acid (2,4-D), 3,4 dichlorophenoxyacetic acid (3,4-D), 2,4,5 trichlorophenoxyacetic acid (2,4,5-T), 4-amino-3,5,6-trichloropicolinic acid (picloram), and 3,6-dichloro-2-methoxybenzoic acid (dicamba) in combination with 0.25 or 0.5 mg·L−1 of two cytokinins type (benzylaminopurine (BAP) and 6-furfurylaminopurine [kinetin (Kin)] in a factorial experiment. The plant growth regulators 2,4-D and 2,4,5-T proved to have a broad spectrum action on somatic embryogenesis induction compared with 3,4-D or picloram. There were no significant differences between the two concentrations of cytokinins. However, Kin was found to be more effective in promoting somatic embryogenesis than BAP. Combining 1 mg·L−1 2,4,5-T or 2,4-D with 0.25 mg·L−1 Kin had a broad spectrum action on embryogenesis induction. On the other hand, combining mg·L−1 picloram with 0.5 mg·L−1 Kin or 1 mg·L−1 3,4-D with 0.25 mg·L−1 Kin was only able to induce somatic embryogenesis in a few of the genotypes evaluated. The protocol developed during the current study differs from earleir works as the callus (derived from explants cultured on DKW media) was taken directly to embryo development media as opposed to earlier works in which the callus was taken through a secondary media before being transferred to an embryo development media.

We investigated the effect of the physical state of the nutrient medium on the induction of somatic embryogenesis on cell cultures derived from coffee (Coffea arabica L.). Non-embryogenic callus tissues were pulsed initially with 50 lM 6-benzyladenine (BA) for 6, 24 or 48 h in half-strength liquid Murashige and Skoog (MS) medium. After pretreatment, calli were transferred to agar-solidified halfstrength MS medium supplemented with 50 lM BA ('standard induction medium'). Control callus tissues were incubated directly on the solid standard induction medium. Callus growth was promoted by longer pretreatment periods. Formation of globular somatic embryos was observed on callus tissues pretreated with BA for 24 or 48 h, which developed fully to cotyledonary-stage within only 2 weeks after transfer to agar-solidified medium supplemented with BA. No embryo formation occurred in control cultures. Pretreatment with BA in liquid medium was associated with changes in the redox status of cultured cells, such as alterations of the ascorbate-glutathione redox systems and the accumulation of free radicals and oxidized lipids, as well as the possible reduction of cytochrome c-mediated apoptotic pathways. In particular, the induction of somatic embryogenesis was highly positively correlated (r 2 = 0.822) with the accumulation of protein carbonyls. The physiological role of BA as an inducer of both embryonic differentiation and cellular death is discussed.

Breeding work carried out during the period 1971–85 by the Coffee Research Institute, Ruiru, Kenya resulted in the release of a new improved hybrid Coffea arabica named Ruiru 11. The cultivar combines resistance to coffee berry disease (CBD) and leaf rust, with high yield and good cup quality attributes. The propagation by F1 hybrid seeds production, cuttings, and tip grafting do not produce enough planting materials. There was a need to explore alternative methods and tissue culture offers potential options. The objective of the study was to evaluate the effect of explant sources and cytokinins on induction and regeneration of somatic embryos. Eight different explants were cultured on half-strength Murashige and Skoog (MS) medium supplemented with 10 µm benzylaminopurine (BAP). The effect of kinetin, N6-(2-isopentyl) adenine (2iP) evaluated at (0, 0.5, 5, or 25 µm) or thidiazuron (TDZ) (0, 0.5, 1.0, or 5 µm) added in separate experiments was also evaluated. The percentage of embryogenic cultures and the numbers of embryos per explant were determined after 3 months’ culture. The explant type had a significant effect (P > 0.05) on the induction of somatic embryos. Explants from in vitro-germinated seedlings produced the highest embryogenic cultures (90%) and the highest mean number of embryos (19.36) per explant. Cytokinins strongly enhanced induction and regeneration of somatic embryos. TDZ at 1 µm produced the highest embryogenic cultures (100%) and the highest mean number of embryos (24.2). The embryos were germinated on half-strength MS medium without any hormones. A high (98%) survival rate of the regenerated plantlets was recorded over all the treatments in the greenhouse. This is the first report on induction of high-frequency direct somatic embryos from coffee juvenile tissues. This is of great significance in tissue culture and indeed molecular biology manipulations because it allows regeneration of coffee from several explants.

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Bamboo is one of the fastest growing and highest yielding renewable natural resources with multiple uses in the world. It is used to make furniture, charcoal, food, control soil erosion and can assist in carbon sequestration. The increasing rate of tropical deforestation calls for search for alternative natural resources and the characteristics of bamboo make it a perfect choice. The major constraint in the use of bamboo is the lack of an efficient propagation method. The objective of this study wase to establish an efficient propagation method and to evaluate the adaptability of different bamboo varieties, to Nyungwe National Park (NNP) and the surrounding zones.The trial was conducted in Nyaruguru District, Ruheru Sector bordering Nyungwe National. Basal, middle and apical cuttings were harvested from three bamboo species (Bambusa vulgaris, Arundinaria alpina and an unknown native bamboo growing naturally in the Nyungwe forests). Results of the trial indicated that the three species were not significantly different in terms of stem diameter. However, the number of sprouts that emerged from cuttings differed with species: Bambusa vulgaris producing 22.2 sprouts, Arundinaria alpina 18.1 and the native bamboo producing 15.0 sprouts. On the other hand, the native bamboo had a mean height of 54.0 cm, while Bambusa vulgaris 36.6 and Arundinaria alpina had 30.8 cm..The soaking treatments did not have significant difference on all the parameters evaluated. This reproducible protocol opens new prospects for propagation of bamboo and will go a long way in alleviating the shortage of planting materials and exploiting the enormous potential of bamboo in Rwanda.

The effect of phytohormones on breaking of dormancy of axillary buds in anchote and their subsequent shoot proliferation were examined. Anchote is an annual trailing endemic plant with high calcium content grown for its edible tuberous roots in Ethiopia. Nodal explants harvested from the greenhouse were sterilized using various concentrations of a commercial bleach (JIK) which contains 3.85% sodium hypochlorite (NaOCl) and time duration. The highest (85%) clean explants were obtained when 5% JIK was used for 15 minutes. The explants were cultured on Murashige and Skoog (MS) medium supplemented with various concentrations of benzylaminopurine (BAP), kinetin, and thidiazuron (TDZ). The highest frequency of microshoot induction (84%) and mean number of microshoots (3.4) were recorded from explants cultured on medium supplemented with TDZ 0.025 µm. Hyperhydrated shoots were observed on media supplemented with high concentrations of BAP and kinetin but interestingly not on TDZ media. Induction of roots was highest (86%; 4.6 roots per shoot) when shoots were transferred to half strength MS medium containing 0.5 μm α-naphthalene acetic acid (NAA) after 12 days. A survival rate of 83% was recorded in the greenhouse and the plantlets appeared to be morphologically normal. This is the first report on use of TDZ for in vitro propagation of anchote.

About 200 Million people in the world suffer from hunger. The United Nations (2007) estimates that the world population will reach 8.1 Billion people by 2030. Meeting global food requirements will necessitate increasing food production by 50%. The most attractive strategy to meet this challenge is to increase smallholder agricultural productivity. This strategy will not only increase food supply, it will also increase smallholder incomes, reduce malnutrition and improve livelihoods of the poor. Biotechnology has the potential to increase the world's food output and reduce food insecurity. Plant biotechnology offers a wide scope of possibilities for increasing productivity, diversification and development of a more sustainable agriculture. This technology includes biopesticide production, plant tissue culture techniques, and the use of advanced molecular biology techniques for plant transformation, genomic analysis coupled with breeding and plant disease diagnoses. Agricultural biotechnology will contribute to food security through technologies that improve yield and quality and can easily be adopted by small scale farmers. The technology should, therefore, be simple, low cost and have little risk to humans and the environment. Tissue culture offers such kind of technology. This communication discusses the status of tissue culture research In Rwanda and how modern biotechnology has led to increased productivity and food security in some developing countries.

Abstract:One way of boosting cocoa productivity which has plummeted over the last decade in Côte d'Ivoire is to introduce high performing clones. Preliminary observations have indicated that these new clones have differing growth patterns and agronomic traits in the field. Assessing their compatibility is of paramount importance since these clones will be made available to the farmers in the near future. This study was conducted in Soubré, southwest of Côte d'Ivoire, to evaluate the compatibility of ten new cocoa clones (coded as C1, C8, C9, C14, C15, C16, C17, C18, C20, and C21). A half diallel design consisting of 10 self-pollinations and 45 inter-crosses, replicated three times, was used. Results showed significant differences among clones for pollination success. Out of the ten clones evaluated, six (C1, C8, C9, C15, C17 and C21) were self-compatible. With a 39% mean pollination success, C9 was quite interesting because it has been reported to be among the highest yielding clones. Introduction of improved germplasm will go a long way towards enhancing productivity in Côte d'Ivoire, radically impact farmers' livelihoods, and contribute significantly to a more reliable supply of cocoa beans for chocolate manufacturers.