Cytokinin-Facilitated Plant Regeneration of Three Species with Different Conservation Status.

In Africa and Asia, members of the genus are well-known for their diverse uses, especially their medicinal and nutritional values. However, the use of many species as a valuable resource is generally accompanied by the concern of over-exploitation attributed to their slow growth and general small size. The aim of the current study was to establish efficient micropropagation protocols for three species, namely (endangered), (vulnerable) and (least concern), as a means of ensuring their conservation and survival. This was achieved using nodal segments (~10 mm in length) as the source of explants in the presence of different concentrations of three cytokinins (CK) namely -benzyladenine (BA), isopentenyladenine (iP) and -topolin riboside (TR), over a period of 6 weeks. The highest (25 µM) concentration of cytokinin treatments typically resulted in significantly higher shoot proliferation. However, each species differed in its response to specific CK: the optimal concentrations were 25 µM TR, 25 µM iP and 25 µM BA for , and , respectively. During the in vitro propagation, both and rooted poorly while regenerated generally lacked roots regardless of the CK treatments. Following pulsing (dipping) treatment of in vitro-regenerated shoots with indole-3-butyric acid (IBA), acclimatization of all three species remained extremely limited due to poor rooting ex vitro. To the best of our knowledge, the current protocols provide the first successful report for these species. However, further research remains essential to enhance the efficiency of the devised protocol.