Regeneration of viable oil palm plants from protoplasts by optimizing media components, growth regulators and cultivation procedures

Abstract

Oil palm protoplasts are suitable as a starting material for the production of oil palm plants with new traits using approaches such as somatic hybridization, but attempts to regenerate viable plants from protoplasts have failed thus far. Here we demonstrate, for the first time, the regeneration of viable plants from protoplasts isolated from cell suspension cultures. We achieved a protoplast yield of 1.14×10(6) per gram fresh weight with a viability of 82% by incubating the callus in a digestion solution comprising 2% cellulase, 1% pectinase, 0.5% cellulase onuzuka R10, 0.1% pectolyase Y23, 3% KCl, 0.5% CaCl2 and 3.6% mannitol. The regeneration of protoplasts into viable plants required media optimization, the inclusion of plant growth regulators and the correct culture technique. Microcalli derived from protoplasts were obtained by establishing agarose bead cultures using Y3A medium supplemented with 10μM naphthalene acetic acid, 2μM 2,4-dichlorophenoxyacetic acid, 2μM indole-3-butyric acid, 2μM gibberellic acid and 2μM 2-γ-dimethylallylaminopurine. Small plantlets were regenerated from microcalli by somatic embryogenesis after successive subculturing steps in medium with limiting amounts of growth regulators supplemented with 200mg/l ascorbic acid.

Keywords: 2,4-D; 2,4-dichlorophenoxyacetic acid; 2-γ-dimethylallylaminopurine; 2iP; 6-benzyl aminopurine; BAP; GA3; IAA; IBA; NAA; Oil palm; PGRs; Plant regeneration; Protoplasts; Suspension cultures; gibberellic acid; indole-3-acetic acid; indole-3-butyric acid; naphthalene acetic acid; plant growth regulators.