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