Diospyros crassiflora H. (Ebenaceae), commercially known as the African ebony, is a small forest tree found at elevations less than 1000 m in South Nigeria, Cameroon, Central African Republic, Equatorial Guinea, Gabon, Republic of the Congo, and Democratic Republic of the Congo (Lemmens et al., 2012). It is a shade-tolerant species characterized by a relatively low growth rate (Bongjoh and Nsangou, 2001). The hard, dense black heartwood of the tree is exploited in Cameroon and other countries for the construction of musical instruments such as the violin, guitar, cello, contrabass, and piano keys (Lemmens et al., 2012; Taylor, 2012). The species is also used locally for medicinal purposes and pharmacological research, and has proven antifungal and antibacterial properties in stem bark extracts (Dzoyem et al., 2007; Tangmouo et al., 2006).
Diospyros crassiflora was listed as vulnerable on the International Union for Conservation of Nature Red List because it is threatened by the destruction of forests for agriculture and grazing, and the commercial logging of other species (Schatz et al., 2019). For now, the species has not been included in extended sylvicultural or agroforestry systems. As part of the Congo Basin Institute’s ebony conservation project, an integrated agroforestry model is currently being developed to compensate for the decrease of tree populations. The development of a cost-effective, reliable approach to large-scale production of the plant is becoming essential for long-term sustainability of the species.
Until now, propagation by seeds has been the main form of propagation of D. crassiflora. However, seed production is seasonal and year dependent. Moreover, reproduction through seeds does not allow genetic fidelity because of its heterozygosity. Vegetative propagation by leafy stem cutting is feasible, but the quantity of plant material available from a selected donor plant is limited and the cuttings maintain the plagiotropic growth of the lateral stem of the cutting (Tsobeng et al., 2011). Our study aimed at developing a protocol of ebony micropropagation that might circumvent the shortcomings of both seedling and cutting propagation.
Micropropagation of the close relatives D. virginiana (Palla et al., 2013) and D. kaki (Mitrofanova and Mitrofanova, 2004; Pijut, 2012) has shown that the development of axillary buds could be induced by cytokinin. PG is a phenolic compound known for its properties as a promoter of plant growth (Teixeira da Silva et al., 2013). The objective of this study was to investigate the effect of cytokinins on the development of axillary buds, and PG on root initiation of D. crassiflora.
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