Cell suspension culture: a potential in vitro culture method for clonal propagation of coconut plantlets via somatic embryogenesis

Cell suspension culture has the potential to achieve more large-scale clonal propagation of coconut (Cocos nucifera L.) via somatic embryogenesis, and to overcome current uncertainty regarding the quality and quantity of available planting materials, replicating the success of the method for the clonal mass propagation of other palm species. Unlike oil palm (Elaeis guineensis Jacq.) and date palm (Phoenix dactylifera L.), a high-quality embryogenic cell suspension culture from coconut tissues and the further regeneration of plantlets have not yet been attained. However, similar to oil palm and date palm, the establishment of coconut embryogenic cell suspension cultures is expected to achieve a high multiplication rate arising from rapid cell production, sustained embryogenic potential, and synchronized somatic embryo production. In addition, coconut genetic potential can be improved at the cellular level through biotechnology applications such as plant transformation, protoplast isolation and genome editing. Based on studies conducted on other palms, there are crucial factors which influence the establishment and growth of cell suspension cultures for palm species that are discussed extensively in this review. There are also constraints within the cell suspension culture system which should be critically reviewed prior to considering their application to coconut. Although there may be limitations, this review proposes that a cell suspension culture step is likely to be crucial to scale-up the clonal propagation of coconut, as it currently appears to be the best method to accomplish large-scale renewal and raised productivity in the coconut industry