Tissue culture and associated biotechnological interventions for the improvement of coconut (Cocos nucifera L.): a review

Abstract

The present review discusses not only advances in coconut tissue culture and associated biotechnological interventions but also future research directions toward the resilience of this important palm crop. Coconut (Cocos nucifera L.) is commonly known as the 'tree of life'. Every component of the palm can be used to produce items of value and many can be converted into industrial products. Coconut cultivation faces a number of acute problems that reduce its productivity and competitiveness. These problems include various biotic and abiotic challenges as well as an unstable market for its traditional oil-based products. Around 10 million small-holder farmers cultivate coconut palms worldwide on c. 12 million hectares of land, and many more people own a few coconut palms that contribute to their livelihoods. Inefficiency in the production of seedlings for replanting remains an issue; however, tissue culture and other biotechnological interventions are expected to provide pragmatic solutions. Over the past 60 years, much research has been directed towards developing and improving protocols for (i) embryo culture; (ii) clonal propagation via somatic embryogenesis; (iii) homozygote production via anther culture; (iv) germplasm conservation via cryopreservation; and (v) genetic transformation. Recently other advances have revealed possible new ways to improve these protocols. Although effective embryo culture and cryopreservation are now possible, the limited frequency of conversion of somatic embryos to ex vitro seedlings still prevents the large-scale clonal propagation of coconut. This review illustrates how our knowledge of tissue culture and associated biotechnological interventions in coconut has so far developed. Further improvement of protocols and their application to a wider range of germplasm will continue to open up new horizons for the collection, conservation, breeding and productivity of coconut.

Coconut Lethal Yellowing Diseases: A Phytoplasma Threat to Palms of Global Economic and Social Significance

“…This may have benefits for public acceptance. Finally, aside from the aforementioned challenges in genetic improvement of coconut, the production of seedlings on a large scale once resistance is identified is also difficult and slow, however improvements in tissue culture methods are showing promise that this process could be improved in the future (Nguyen et al, 2015). …”

Biology, propagation and utilization of elite coconut varieties (makapuno and aromatics)

“…This result supports the view that the makapuno genotype is preserved through in vitro embryo culture. However, the cultivation of the embryo culture-produced seedlings cannot guarantee the production of a trueto-type palm since a makapuno-bearing palm is presumably heterozygous [3]. Recent research using DNA-based markers has developed a way to identify planting material that is carrying the makapuno trait, by assessing visually its genetic make-up in the young [23] and mature palms (53).…”

“…[2]. In addition, the field cultivation of coconut in some regions has been seriously threatened by a wide variety of biotic and abiotic factors, including lethal diseases and pests, and natural calamities [3]. The major era of establishment of coconut plantations for export of copra and oil was the period of its very high price, between the years 1900 and 1930.…”

“…The capacity provided by cloning technology, to multiply material from resistant or tolerant populations, would provide a means to achieve protection [3]. Hence, there is an urgent need to foster alternative coconut products with higher economic value, which can help sustain the viability of the smallholder and the entire coconut industry.…”

Cryopreservation of Brazilian green dwarf coconut plumules by droplet-vitrification

“…Recent studies have shown the feasibility of the vitrification technique for the cryopreservation of BGD zygotic embryos (LEDO et al, 2018). Moreover, regeneration techniques by somatic embryogenesis from plumules are more interesting from the point of view of breeding and conservation of genetic resources because they allow obtaining higher number of plants (NGUYEN et al, 2015).…”