Development of in vitro clonal propagation protocols for Moringa oleifera

Abstract

Conventional propagation of Moringa oleifera involves the use of seeds and cuttings. However, being a crop of high economic value and demand, it is required to apply fast and efficient biotechnological methods to propagate this crop and improve traits of interest in order to ensure its availability in the market. As such, in vitro clonal propagation protocols for Moringa oleifera were developed with an objective of determining early graft compatibility between M. oleifera and M. stenopetala. Leaves obtained from greenhouse grown Moringa oleifera and Moringa stenopetala plants were used for callus induction and fusion experiments. Leaves from both species were cultured on Murashige and Skoog (MS) medium supplemented with six different growth regulators [(0.2 mg -l α-naphthalene acetic acid (NAA)), (0.2 mg -l Dichlorophenoxyacetic acid (2,4D)), (0.02 mg -l Thidiazuron (TDZ)), (0.2 mg -l NAA + 0.02 mg -l TDZ), (0.2 mg -l 2,4D + 0.02 mg -l TDZ) and (0.2 mg -l NAA + 0.2 mg -l 2,4D + 0.02 mg -l TDZ)]. Two pieces of callus were excised and co-cultured on MS medium supplemented with 0.02 mg -l TDZ in combination with 0.2 NAA mg -1. After a month of culturing, co- cultures were prepared for viewing under a light microscope to determine compatibility by the presence of a necrotic line, union line and phenolic compounds. Combinations of 0.02 mg -l TDZ and 0.2 mg -l NAA were effective supplements for callus induction. Moringa oleifera and Moringa stenopetala co-cultures had high phenolic deposits at the graft interface. The high accumulation of phenolic compounds at graft interfaces is highly associated with incompatibility since these compounds prevent auxin transport. Consequently, the species were regarded as incompatible.