Is cryopreservation a viable method for long-term conservation of coffee biodiversity?

Coffee beans. Photo: Bioversity/M.Hermann

Conserving coffee diversity is key to securing its future. Photo: Bioversity/M.Hermann

The value of conserving coffee diversity

Coffee (Coffea spp.) is not only one of the most popular drinks in the world, but it is also the world's most valuable agricultural export commodity. In 2007, it had an export value of US$6.2 billion.  Most coffee is produced in the developing world by smallholder farmers, many of whom are resource poor and dependent on coffee trade for their livelihoods. 

Coffee crop success depends on the availability of diversity to enhance its genetic base and to provide resistance to pests and diseases. Yet deforestation, unsustainable agricultural methods, population increase and economic hardship are placing these natural resources under threat, creating an urgent need to collect and conserve coffee genetic resources so that we can secure its future. 

But this is not a straightforward process. Coffee cannot be conserved as seed using conventional methods, such as drying and storing it at a low temperature, so it is usually conserved by growing it out in the open - in field genebanks. But there are many disadvantages to this method - it is expensive, it can be high risk as rare samples (accessions) can be lost, for example, through fire, extreme weather, pests or disease, and it also requires a lot of maintenance such as regular regeneration and weeding. 

But new techniques in cryopreservation, which conserves genetic resources at very low temperatures, for example, at -196*C with liquid nitrogen, could offer a viable alternative.

Counting the beans - can deep-freezing coffee diversity be a viable conservation option?

The objective of this study was to assess the potential impact of the widespread adoption of cryopreservation techniques for conserving genetic diversity in terms of cost effectiveness and genetic erosion, using coffee as a case study. 

Researchers at the Institut de Recherche pour le Développement   [1]in France developed and optimized a cyropreservation protocol for coffee seeds which was transferred to the Centro Agronómico Tropical de Investigación y Enseñanza (CATIE  [2]) in Costa Rica, with support from Bioversity International. CATIE manages one of the largest field collections of Coffea arabica in the world - with 1,992 accessions - and by conducting the study in the same location, it was possible to create comparative costs.

For the study, the new protocol was applied to 63 genetically distinct coffee varieties, creating the first coffee cryo-bank in the world. A detailed cost study was then carried out on the field genebank and the cryo-collection at CATIE, comparing capital, quasi-fixed, variable and in-perpetuity costs.

Conserving coffee diversity is key to its success - but what is the most effective way? E.Dulloo/Bioversity

Conserving coffee diversity is not straightforward - but which is the most effective method? Photo: E.Dulloo/Bioversity

Comparative cost data at CATIE showed that for a collection of 63 accessions, cyopreservation is not the most cost effective option - it cost 33% more per accession than that in the field collection. But projections estimated that the cost per accession would fall as the collection size increased. For example, for a collection of 2000, the costs would fall to US$55, which is 21% less than that of the field collection (full details of the cost analyses can be found in the Impact Assessment Brief below). 

Another important consideration is the annual maintenance costs which are much smaller than for a field collection - around 50% less. Material in field genebanks must be regularly regenerated to prevent loss, which makes them more vulnerable to loss if operating funds are unavailable, even for just one year. If the collections hold rare or endangered germplasm, this could cause extinction.

An analysis of coffee field collection loss carried out as part of this study, showed minimal loss for well-funded collections such as those in Brazil and Kenya, compared to a 46% loss in Madagascar which has hardly any funds set aside for maintenance. Maintenance could include activities such as weeding and control of pest and diseases.

Other advantages for using cryopreservation techniques include a greater capacity to store diversity using much less physical space. The conservation of 1,992 coffee accessions at CATIE required 9 hectares of land while the same number could be cryopreserved within 10 square metres.

Conclusions

Given the importance of genetic diversity to coffee producers - many of whom are smallholder farmers depending on coffee for their livelihoods - policymakers should help create opportunities for establishing additional cryo-collections to ensure the future health of the crop.  A regional or global cryopreserved collection could be established for coffee (as it has been done for banana) in which the costs of cryopreservation and the benefits could be shared among partner countries.  It can be a complementary conservation technique along with field genebanks or partly replace them, and could be relevant to other species that are difficult to conserve.

Further studies are needed to establish the optimal balance between between cryopreservation and field collections to ensure the long term, cost-efficient conservation of coffee genetic resources.
 

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Filed under: Impact Assessment  [10], Conservation  [11]See also: Coffee  [12], Costa Rica  [13], Cryopreservation  [14], Impact Assessment  [15]

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