Challenges associated with the conservation of coconut diversity and its use in selection and breeding
Coconut is the sixth most cultivated fruit in the world. Coconut roots, trunk, leaves, and the different components of its fruits (husk, shell and kernel, water and “apple”) are used for food, medicinal purposes, housing, wood energy, furniture, handicrafts. The demand for fresh nuts, mainly for coconut water and coconut milk production, is constantly growing.
The biggest coconut producing countries in the world are in South Asia, South East Asia and South Pacific. Coconut is also widely grown in Africa and Latin America.
Coconuts are generally grown by smallholder farmers who consume them for food and drink and sell them in local domestic markets, often as copra (the dried meat or kernel of the coconut, from which the oil is extracted). The coconut value chain is complex due to the many products that can be derived from the coconut palm, with links from local to international markets.
Pests and diseases, among them the devastating Lethal Yellowing (LY) disease, climate change, rising sea levels, and land-use changes threaten coconut production systems and coconut tree genetic diversity. These pressures are exacerbated by the fact that a growing proportion of coconut production relies on senile coconut palms (from 50 to 100 years old). Old palms need to be removed to make way to young, more productive successors, but the pressure on coconut product supplies and the lack of access to good quality planting material make farmers reluctant to substitute the senile palms as long as they keep on producing some nuts. These challenges call for the selection, development and dissemination of varieties that can help farmers maintain coconut production in a sustainable way and respond to growing market demands.
Coconut seeds are difficult to preserve because of their extremely large size and because they are recalcitrant, i.e., they cannot resist the effects of drying and low (-20°C) temperature exposure applied in ex-situ seed genebanks and they cannot be stored for long periods without losing viability. Consequently, coconut genetic resources are conserved as trees in field genebanks, where they are subject to the pressures mentioned above.
Coconut breeders and farmers currently obtain coconut planting material through seed propagation: coconuts are harvested from a mother tree and put to germinate in a seedbed after removing part of their husk. The low number of coconuts available from mother trees (70-100 per year) and the diverse genetic composition of the harvested seed limit the efficiency of this method. In addition, the risk that pests and diseases are passed on from the mother tree to the progeny is high.
In vitro techniques have, to date, only been partially successful in addressing these challenges to conserving and multiplying coconut reproductive materials. Until now, in vitro tissue culture was mainly focused on zygotic embryo culture and the somatic embryogenesis technique. Zygotic embryos removed from the nut can be cryopreserved, and then regenerated through in vitro culture in order to obtain plants that can be planted in the field. However, with current methods, cryopreservation of zygotic embryos is not yet optimized and thus not applied as a routine conservation technique, and the shoots derived from these embryos cannot be multiplied.
The somatic embryogenesis technique makes use of explants containing young meristematic tissues and high concentrations of synthetic auxins to create an embryogenic callus. This callus is then used to generate somatic embryos that can subsequently develop into new cloned plantlets. The main limitations of this technique are 1) the induction rate to create an embryogenic callus is low and probably genotype-dependent, and 2) callus is prone to somaclonal variation (mutations taking place during in vitro culture), which may result in undesired changes at genetic and phenotypic levels.
A new promising method for clonal propagation of coconut
Scientists from the Alliance of Bioversity International and CIAT, and KU Leuven with financial support from Rural Development Administration of South Korea (RDA) have developed a clonal propagation method that overcomes the limitations of the existing techniques and technologies described above, by allowing in vitro clonal propagation of shoots without the problems or risks associated to somatic embryogenesis. This method starts from coconut plantlets originating from zygotic embryos derived from mature coconuts. The plantlets are trimmed resulting in a disc that contains the meristem. This disc is then longitudinally divided into two equal pieces that are transferred for proliferation in a solid medium with a particular composition. These manipulations activate the development of new meristems in almost 30 percent of the initial plantlets. By avoiding the callus phase and inducing the development of shoots directly from the apical meristem, this method minimizes somaclonal variation. This is the first time that large-scale clonal propagation of coconuts by shoot multiplication has been observed. In theory, thousands of plants can be produced from one embryo applying this technique.
This invention has the potential to greatly improve in vitro conservation and multiplication of coconut genetic resources, which are preconditions for the effective preservation of Cocos spp. diversity, its use in breeding and farming, and the effective multiplication and dissemination of new, uniform, disease-free planting material to farmers.
The method should work on all coconut plants; it is not limited to specific varieties or populations.
The method needs further optimization. In particular:
- It has to be applied to a wider range of coconut genotypes.
- Factors contributing to the development of abnormal structures that are sometimes found in the shoots need to be understood and minimized.
- Development of the shoots into rooted plants has to be further studied and possibly improved.
- Resulting plants need to be studied in the field to confirm the absence of somaclonal variation.
- The application of the technique to other palm trees needs to be tested.
Two to three years will be necessary to refine the method and the in vitro protocols, and from six to eight years to test the regenerants in the field.
In addition to financial resources, it is necessary to test materials in experimental fields in a diversity of agroecosystems and environments. For these purposes, KU Leuven, RDA and the Alliance of Bioversity International and CIAT seek to attract partner organizations that can contribute financial and technical support to the further development, refinement and utilization of the technique. Once the technology is ready for utilization at scale, the Alliance, RDA and KU Leuven will continue reaching additional potential users who can use the invention for the benefit of coconut growers in developing countries. While micropropagation is the most commercially exploited area of plant tissue culture and is being widely used for production of quality planting material in vegetatively propagated species such as bananas, its presence in many developing countries is still modest. The lack of robust seed systems and of a stable demand for in vitro planting material and the level of sophistication of in vitro technologies can explain why this industry has not still spread in poor countries. This new technique has the potential to incentivize the development of the micropropagation industry in developing countries.
Seeking patent protection
In January 2019 Bioversity, RDA and KU Leuven applied for a patent over this method for clonal propagation of coconut in the UK. The application does not extend to products. This first provisional application was confirmed with a Patent Cooperation Treaty application submitted to the European Patent Office on 27 January 2020.
Our motivation in seeking the patent is to create incentives for other organizations to partner with us, and make requisite investments to a) continue the development of the invention, and b) to scale up the use of the invention so that it has desired impact on the availability of quality coconut materials for small holder farmers in developing countries. If and when the patent is granted, Bioversity, RDA and KU Leuven will be able to provide partners and investors limited exclusivity rights to exploit the invention commercially.
The increasing interest for coconut water and oil by the food and beverage industry is likely to increase demand for good planting material in coconut producing countries, beyond that which already exists as described above. Ultimately, we hope to leverage investment from private and public organizations that are commercializing coconut products to develop and use the invention for the benefit of small-scale farmers who need access to quality coconut materials.
Principles that will guide the exploitation of the invention
The Alliance of Bioversity and CIAT, RDA and KU Leuven will make the invention available for use, free of charge, for non-commercial research and development.
We will develop licenses with organizations that want to exploit the invention for commercial purposes in specific geographic areas for limited periods of time.
Each license will be negotiated on a case by case basis, in accordance with the following principles:
- Licensees must ensure quality control along the process and of the resulting plants.
- Resulting planting material must reach smallholder farmers at an affordable price. If it is the intention of the licensee to exploit the technology to provide planting material to farmer-producers under contract with the licensee, the licensee must also make planting materials developed through the use of the technology available for farmers who are not under such contracts, at a reasonable cost taking into consideration the situation of small farmers in that country.
- The Alliance of Bioversity and CIAT, KU and RDA will monitor the extent to which planting material is reaching smallholder farmers at an affordable price. To assist in this effort, the licensee will be required to produce evidence that it is making materials available to farmers at reasonable prices. If it is not doing so, the license will be revoked.
- The Alliance will require licensees to make payments based on their sales of planting materials to the Benefit Sharing Fund of the International Treaty on Plant Genetic Resources for Food and Agriculture. Since the invention does not incorporate material form the Treaty’s multilateral system, the commercialization of the invention and products derived thereof is not expected to trigger the monetary benefit sharing obligations under the Multilateral System of Access and Benefit Sharing of the Treaty. The Alliance will voluntarily include such payments in the licenses as a contribution to the conservation and sustainable use of plant genetic resources.
- Other forms of benefit-sharing such as research partnerships, technology transfer and information sharing will be explored with research partners in coconut producing countries and with the International Coconut Genetic Resources Network.