Optimization of Coconut Micropropagation via Somatic Embryogenesis ^†

Abstract

Coconut (Cocos nucifera L.) is one of the most important tropical palm crops worldwide, but the gap between decreasing productivity and expanding demand is growing and is now becoming a major problem. The global coconut industry is threatened not only by palm senility but by pests/pathogen attack which is becoming exacerbated by climate change. However, conventional breeding methods cannot provide sufficient new planting materials to meet the replacement of senile and damaged palms. Hence, coconut clonal propagation via somatic embryogenesis (SE) is being developed to help meet the demand of the growing market. However, with refined medium composition, improved technical skills, optimized environmental conditions, proper acclimatization steps employed and the application of a cell suspension culture step, a much higher multiplication rate can be predicted. Several factors that affect the rate of clonal propagation are being studied: 1) determination of the effect of a non-activated charcoal (AC) medium and 2) the development of culture induction medium composition with a reduced auxin concentration. Results of the study so far show that a non-activated charcoal medium with more frequent subculture (monthly) and a lower auxin concentration is an efficient alternative approach to the traditional mainstream AC-containing medium for the initiation of embryogenic callus. With a better understanding of the callus induction medium composition, and with a liquid cell suspension culture step medium to be applied in the future, should elevate the multiplication rate of clonal plantlet production.