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Using cryopreservation to conserve crop germplasm is reliable and, contrary to popular belief, cost competitive with field genebanks

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April, 2009

Source: CGIAR newsletter, April 2009

Using cryopreservation to conserve crop germplasm is reliable and, contrary to popular belief, cost competitive with field genebanks

Coffee is big business. The trade in coffee is among the world’s most valuable for an agricultural commodity, with an annual export value in excess of US$6.2 billion. Most coffee-producing countries are in the developing world, where coffee is grown predominantly by small-scale farmers who are often poor. The coffee trade is vital to their livelihoods.
 

Coffee seeds germinating after being frozen to -196 degrees C using a cryopreservation protocol. Stephane Dussert. IRD.

 

The success of the crop — and of the whole industry built upon it — depends on the availability of diversity to enhance the genetic base of coffee. This diversity is needed to provide resistance to coffee berry disease, coffee rust, fusarium wilt, bacterial blight, nematodes, and major insect pests, as well as adaptation to abiotic stresses such as climate change and drought, to say nothing of the drive to enhance aroma and flavor.

In 1998, the Food and Agriculture Organization (FAO) of the United Nations published a report entitled The State of the World’s Plant Genetic Resources for Food and Agriculture, which noted the conservation of 21,000 accessions of coffee. All this diversity has traditionally been conserved in field genebanks, which present real security challenges. A single cyclone in Madagascar, for example, could destroy the unique field collections of Mascarocoffea species that are important because many contain little or no caffeine, traits of interest to breeders. And that is not just speculation; a cyclone did destroy the coffee collection at Ilaka Est. Fortunately, the collection was duplicated at another site on the island, Kianjavato, and only a few accessions were lost.

Across the world many field genebanks, not just for coffee, are thought to be vulnerable because of such environmental and economic factors as pests and diseases, extreme weather, fire, vandalism, lack of funds and policy changes. To ensure real security and future diversity, a new approach is needed.

One solution is cryopreservation. With this super-freezing technique, living tissues are conserved at -196ºC in liquid nitrogen to arrest the cells’ metabolic activity. While some species, such as Musa (banana and plantain), are increasingly well catered for in cryopreservation, until now there have been doubts about the practical delivery of coffee cryopreservation and whether the economics add up.

For the past 15 years or so, Bioversity International and many of its partners have invested in developing and adopting cryopreservation by researching, testing and documenting protocols; training technicians and scientists; and supporting the acquisition of equipment for cryopreservation. As part of this effort, genebank managers and cryopreservation specialists were surveyed in 2006 to assess the obstacles. One fascinating result the survey identified was a general belief that cryopreservation was expensive, even though very few studies have analyzed the actual costs or effectiveness of cryopreservation, and even fewer have gone further to compare the costs of cryopreservation with those of maintaining field genebanks.

A new study led by Ehsan Dulloo, a Bioversity scientist, 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, its acronym in Spanish) in Costa Rica. The bottom line is that cryopreservation costs less in perpetuity per accession than conservation in field genebanks. 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 is reported by others, such as the cost to the United States Department of Agriculture (USDA) for establishing a cryocollection of temperate fruit at Corvallis on the US west coast.

A vital partner in the work was the Institute of Research for Development (IRD) in France, Dulloo notes. The coffee cryopreservation technique was developed by IRD in the framework of joint projects with Bioversity and CATIE, and the beauty of the protocol is that it allows the cryopreservation of whole seeds.

“Most cryopreservation conserves parts of the plant, like cells or just the growing tip, and these then need to be grown into whole plants to regenerate the collection,” Dulloo explains. “Cryopreservation of whole seed makes regeneration very easy and much less expensive.”

IRD’s experience enabled the detailed cost calculations of the project. To keep those costs to a minimum in the future, the solution may be a regional or global cryopreserved collection for coffee germplasm. As demonstrated by other crops such as Musa, this would allow the costs of cryopreservation and the benefits derived from germplasm conservation to be shared among partner countries.

 

 

 

 

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