Coffee is big business, but its continued harvest will depend on the availability of diversity to enhance its genetic base. This is necessary to provide valuable traits such as resistance to diseases, adaptation to abiotic stresses such as heat and drought, caffeine content, aroma, and flavor.
This vital diversity does exist. In 1998, the Food and Agriculture Organization (FAO) of the United Nations reported that 21,000 accessions of coffee were conserved in field genebanks. But field genebanks present real security challenges; they are vulnerable to pests and diseases, extreme weather, fire, vandalism, lack of funds, and policy changes. A single cyclone in Madagascar, for example, destroyed a unique field collection of Mascarocoffea species that are important because many contain little or no caffeine, a trait of great interest to breeders. Fortunately, the collection had been duplicated at another site on the island, and only a few accessions were permanently lost.
Real security and future diversity requires a new approach. One solution is cryopreservation. With this superfreezing technique, living tissues are kept at –196ºC in
liquid nitrogen to arrest the cells’ metabolic activity. Cryopreservation is being increasingly used for some species, such as those belonging to the Musa genus (banana and plantain), but until now, there have been doubts about the practical delivery of coffee cryopreservation and whether the economics add up.
Comparing the costs over the past two decades, Bioversity International and its partners have promoted cryopreservation by researching, testing, and documenting protocols and training technicians and scientists. As part of this effort, genebank managers and cryopreservation specialists were surveyed in 2006 to assess the obstacles. One fascinating discovery from the survey was a general belief that cryopreservation was expensive, even though very few studies have analyzed its actual costs or effectiveness and even fewer have compared the costs of cryopreservation with those of maintaining field genebanks.
A new study published in the November–December issue of Crop Science compared the costs of maintaining one of the world’s largest field collections of coffee with those of establishing a coffee cryocollection at the Center for Research and Higher Learning in Tropical Agriculture (CATIE) in Costa Rica.
“Our study showed that cryopreservation costs less in perpetuity per accession than conservation in field genebanks,” says lead researcher Ehsan Dulloo, a Bioversity International scientist working in close collaboration with the Institute of Research for Development (IRD) in France. “And the more accessions that are cryopreserved, the lower the cost per accession.”
The team’s calculations show the initial cost of establishing a cryocollection with 2,000 accessions is US$110,055, or $55 per accession. That is less than the cost of a field
collection of some 1,992 accessions, which is $138,681, or $69.62 per accession. These figures are in the same cost range of $50-75 per accession that has been reported by
the USDA for establishing a cryocollection of temperate fruit in Corvallis, OR.
“Most cryopreservation techniques conserve parts of the plant, like cells or just the growing tip, and these then need to be grown in vitro into whole plants to regenerate
the collection,” Dulloo explains. “But with our partner, IRD, we developed a coffee cryopreservation protocol for whole seeds, which makes regeneration very easy and
much less expensive.”
A cost-effective solution for the future may be a regional or global cryopreserved collection of coffee biodiversity. This is the approach used with Musa spp., and it
allows the costs of cryopreservation and the benefits derived from biodiversity conservation to be shared among partner countries.
Adapted from M.E. Dulloo, A.W. Ebert, S. Dussert, E. Gotor, C. Astorga et al. 2009. Cost efficiency of cryopreservation as a long-term conservation method for coffee genetic resources.
Crop Sci. 49. The full article will be posted online by mid-November at http://crop.scijournals.org/content/vol49/issue6
F1 hybrid arabica coffee at CICAFE (experiment station of the Costa Rican Coffee Research Institute). Photo by F. Anthony, IRD.