Ecology and Development Series No. 10, 2003 - ZEF

Current state of knowledgestorage, and "storage" of living plants in field gene banks and botanical gardens. Amongthese, two methods, namely in vitro conservation and field gene banks, are the onlyrelevant methods for conservation of coffee genetic resources.In vitro conservationBasically, in vitro conservation involves the maintenance of explants in a sterile, pathogenfreeenvironment and is widely used for vegetatively propagated and recalcitrant-seededspecies. It offers an alternative to field gene banks. Recently, numerous in vitro techniquesfor short-term (slow growth) and long-term storage (cryopreservation) of coffee germplasmhave been developed (Dussert et al. 1997a; Engelmann 1997). For long-term storage,cryopreservation is the only method with great promise. Research on the development ofcryopreservation techniques has been performed with seeds, zygotic embryos, apices, andsomatic embryos (Dussert et al. 1997a).Dussert et al. (1997b, 1998) show that partially desiccated seeds of C. arabica can becryopreserved if they are slowly precooled down to – 50 0 C prior to their immersion intoliquid nitrogen. This is the optimal temperature for transfer of C. arabica seeds to liquidnitrogen (Dussert et al. 2002). Until recently, the number of seeds that developed intonormal seedlings remained low, even when cryopreserved under optimal conditions(Dussert et al. 2000a). It was found, however, that seed osmo-conditioning, i.e., controlledrehydration of seeds in a solution with low osmotic potential could have an extremelybeneficial effect on seedling recovery after cryopreservation (Dussert et al. 2000b). Thefirst cryopreserved C. arabica gene bank was established at CATIE (Dussert et al. 2002).Currently, duplicates of CATIE’s C. arabica core collection accessions are beingsuccessfully cryopreserved. This is the first ex situ conservation method which enablestorage of coffee seeds in gene banks.Field gene banksConservation in field gene banks, like any other kind of ex situ conservation, involvescollection of materials from different geographical locations and planting at one location.They are mainly established to conserve the genetic resources of recalcitrant species, sterile22