2.4 Methods for Conservation of PGRFA
35
conservation is defined here as all activities to conserve PGRF A in their common
surroundings. Although this is a quite practical definition already, there will still
be a scope, where conservation activities cannot be clearly classified. Both
conservation methods shall be described and analyzed in the following section.
2.4.1
Ex Situ Conservation Management
Following the three defmed objectives for conservation, the ex situ conservation
methods must be analyzed; the existing management of conservation must be
described in the following section.
The ex situ conservation of plant genetic resources developed largely from
earlier efforts by botanists and plant breeders to collect and use crop genetic
diversity in their breeding programs. There is a variety of different possibilities to
store PGRF A ex situ:
• seed gene banks: the conservation of all the major cereals dried to a low
moisture content and stored at low temperatures over long periods of time.
• field gene banks: for food crops which cannot be conserved as seeds. The plants
are grown and managed in fields as living collections of accessions with short
up to medium term conservation.
• in vitro: for vegetatively-propagated species and species with recalcitrant seeds
as sterile plant tissue or plantlets either under slow growth conditions on
nutrient gels for short or medium-term conservation or in liquid nitrogen
(cryopreservation) for the long-term conservation.
In the literature, in vitro storage is mostly a synonym for slow-growth storage. But
cryopreservation is another in vitro conservation method of increasing
importance. Cell division and metabolic processes are stopped due to
temperatures of minus 196°C, and plant material can be stored without alteration
for long periods of time. Cryopreservation is a promising option for the safe, longterm storage of germplasm of those species which can easily be regenerated into
whole plants, of vegetatively-propagated species and species with recalcitrant
seed (Withers, 1990). Cryopreservation may also be used as a technique for the
long-term storage of many orthodox species (Stanwood et aI., 1981).
The theoretical differentiation between base collection as the long-term
storage, which conserves plant genetic resources for the future and the active
collection - as that part of the base collection, which is utilized at present is of
significant importance for the analysis of conservation activities. Although this
differentiation of different collection types exists in theory, the financial,
management and other restrictions do not always enable the genebanks to divide
their collections into base and active collections. The majority of genebanks have
only one type of collection, which is used for all of the different purposes
(WIEWS, 1996).
35
conservation is defined here as all activities to conserve PGRF A in their common
surroundings. Although this is a quite practical definition already, there will still
be a scope, where conservation activities cannot be clearly classified. Both
conservation methods shall be described and analyzed in the following section.
2.4.1
Ex Situ Conservation Management
Following the three defmed objectives for conservation, the ex situ conservation
methods must be analyzed; the existing management of conservation must be
described in the following section.
The ex situ conservation of plant genetic resources developed largely from
earlier efforts by botanists and plant breeders to collect and use crop genetic
diversity in their breeding programs. There is a variety of different possibilities to
store PGRF A ex situ:
• seed gene banks: the conservation of all the major cereals dried to a low
moisture content and stored at low temperatures over long periods of time.
• field gene banks: for food crops which cannot be conserved as seeds. The plants
are grown and managed in fields as living collections of accessions with short
up to medium term conservation.
• in vitro: for vegetatively-propagated species and species with recalcitrant seeds
as sterile plant tissue or plantlets either under slow growth conditions on
nutrient gels for short or medium-term conservation or in liquid nitrogen
(cryopreservation) for the long-term conservation.
In the literature, in vitro storage is mostly a synonym for slow-growth storage. But
cryopreservation is another in vitro conservation method of increasing
importance. Cell division and metabolic processes are stopped due to
temperatures of minus 196°C, and plant material can be stored without alteration
for long periods of time. Cryopreservation is a promising option for the safe, longterm storage of germplasm of those species which can easily be regenerated into
whole plants, of vegetatively-propagated species and species with recalcitrant
seed (Withers, 1990). Cryopreservation may also be used as a technique for the
long-term storage of many orthodox species (Stanwood et aI., 1981).
The theoretical differentiation between base collection as the long-term
storage, which conserves plant genetic resources for the future and the active
collection - as that part of the base collection, which is utilized at present is of
significant importance for the analysis of conservation activities. Although this
differentiation of different collection types exists in theory, the financial,
management and other restrictions do not always enable the genebanks to divide
their collections into base and active collections. The majority of genebanks have
only one type of collection, which is used for all of the different purposes
(WIEWS, 1996).