Conservation Systems in situ and ex situ

1
Conservation Systemsin situ and ex situ
HCS 830 Plant Genetic Conservation

• Samuel Contreras
• October - 2003

2
Introduction

• Concepts and importance of conservation of plant
  genetic resources.

3
Introduction

• The conservation/ development paradox.

Genes used to breed new varieties
Primitive forms, wild species, landraces,
traditional varieties
Modern varieties
(IPGRI, 1993 cited by Hawkes et al. 2000)
4
Introduction

• The conservation/ development paradox.

Genes used to breed new varieties
New varieties replaces original types
Primitive forms, wild species, landraces,
traditional varieties
Modern varieties
Genetic diversity available in the field for
breeding reduced
(IPGRI, 1993 cited by Hawkes et al. 2000)
5
Introduction

• A simple model of plant genetic conservation
• Conservation is the process that actively retains
  the diversity of the gene pool with a view to
  actual or potential utilization.
• Utilization is the human exploitation of that
  genetic diversity.
• (Hawkes et al., 2000)

Gene pool
Conservation
Utilization
6
Introduction

• A more complex model

(Maxted et al., 1997)
7
Introduction

• A more complex model

• Financial, temporal and technical limitations
• Make the most efficient selection of species to
  conserve
• Factors to considerate
• Conservation status
• Potential economic use
• Threat of genetic erosion
• Genetic distinction
• Ecogeographic distinction
• National or conservation agency priorities

Taxa selection
(Maxted et al., 1997)
8
Introduction

• A more complex model

• Establishes the objectives of the conservation
  and justifies its selection, specifying the
  target taxa and target areas, how the material is
  to be utilized,where the conserved material is to
  be safety duplicated, etc.
• Compilation of ecological, geographical and
  taxonomic data.

(Maxted et al., 1997)
9
Introduction

• A more complex model

• Which populations require conservation?
• Can local farmers play a part in conservation
  activities?
• Do population levels require close monitoring?
• Should a national or international collecting
  team be directed to collect the priority target
  data?
• What conservation strategies are appropriate?
• What combination of conservation techniques is
  appropriate?
• Is a more detailed study required?

(Maxted et al., 1997)
10
Introduction

• A more complex model

• The conservationist must attempt to conserve the
  range of diversity that best reflects the total
  genetic diversity of the species.
• How many plants must be sampled?, Which plant and
  what pattern of sampling is appropriate?

(Maxted et al., 1997)
11
Introduction

• A more complex model

• Whish are the possibilities?
• What are the advantages and disadvantages of
  each one?

(Maxted et al., 1997)
12
Conservation Strategies

• Seed storage
• In vitro storage
• DNA storage
• Pollen storage
• Field gene bank
• Botanical garden

Ex situ

• Genetic reserve
• On- farm
• Home gardens

In situ
(Maxted et al., 1997)
13
Conservation Strategies

• Definitions
• Ex situ conservation means the conservation of
  components of biological diversity outside their
  natural habitats.
• In situ conservation means the conservation of
  ecosystems and natural habitats and the recovery
  of viable populations of species in their natural
  surrounding and, in the case of domesticates or
  cultivated species, in the surrounding where they
  have developed their distinctive properties.
• (article 2 of the Convention on Biological
  Diversity UNCED, 1992
• UNCED United Nations Conference on the
  Environment and Development)

14
Ex situ techniques

• Genetic variation is maintained away from its
  original location.
• These techniques are generally appropriate for
  the conservation of crops, crop relatives and
  wild species.

(Maxted et al., 1997)
15
Ex situ techniques

• Seed storage conservation
• Collection of seed samples at one location and
  their transfer to a gene bank for storage. The
  samples are usually dried to a suitable low
  moisture content and then kept a sub-zero
  temperatures.

Conserved germplasm in long-term storage at the
IRRI gene bank
(Hawkes et al., 2000)
16
Ex situ techniques

• Seed storage conservation

• Advantages
• Efficient and reproducible
• Feasible for medium and long-term secure storage
• Wide diversity of each target taxon conserved
• Easy access for characterization, evaluation and
  utilization.
• Little maintenance once the material is
  conserved.

• Disadvantages
• Problems storing seeds of recalcitrant species
• Freezes evolutionary development
• Genetic diversity may be lost with each
  regeneration cycle

(Maxted et al., 1997)
17
Ex situ techniques

• In vitro storage
• Collection and maintenance of explants (tissue
  samples) in a sterile, pathogen-free environment.

CIP, in vitro gene bank (www.cipotato.org)
In vitro culture of banana germplasm
(Hawkes et al., 2000)
18
Ex situ techniques

• In vitro storage

• Advantages
• Relatively easy long-term conservation for large
  number of recalcitrant, sterile or clonal species
• Easy access to evaluation and utilization

• Disadvantages
• Risk of somaclonal variation
• Need to develop individual maintenance protocols
  for most species
• Relatively high level technology and maintenance
  costs

(Maxted et al., 1997)
19
Ex situ techniques

• Field gene bank
• Collection of seed or living material from one
  location and its transfer and planting at second
  site. Large numbers of accessions of a few
  species are usually conserved.

Characterization and evaluation of Taro, Papaya
and Otaheite in Java (IPGRI).
(Hawkes et al., 2000)
20
Ex situ techniques

• Field gene bank

• Advantages
• Suitable for storing material of recalcitrant
  species
• Easy access for characterization, evaluation and
  utilization

• Disadvantages
• Material is susceptible to pests, diseases and
  vandalism
• Involves large areas of land, but even then
  genetic diversity is likely to be restricted
• High maintenance cost

(Maxted et al., 1997)
21
Ex situ techniques

• Botanic garden/ arboretum
• Collecting of seed or living material from one
  location and its transfer and maintenance at a
  second location as living plant collection of
  species in a garden (or arboretum for tree
  species). Small numbers of accessions of a large
  number of species are usually conserved.

Paste picture
Royal Botanical Garden, Kew
(Hawkes et al., 2000)
22
Ex situ techniques

• Botanic garden/ arboretum

• Advantages
• Freedom to focus on wild plants and no-economic
  plants
• Easy public access for conservation education

• Disadvantages
• Space limit the number and genetic diversity of
  the species conserved
• Involves large areas of land
• High maintenance costs in glasshouse once
  conserved

(Maxted et al., 1997)
23
Ex situ techniques

• DNA/ Pollen storage
• Collection of DNA or pollen and storage in
  appropriate, usually refrigerated conditions.

• Advantages
• Relatively easy, low cost of conservation

• Disadvantages
• DNA -Regeneration of entire plants from DNA can
  not be envisaged at present
• Problem with subsequent gene isolation, cloning
  and transfer
• Pollen -Need to develop individual regeneration
  protocols to produce haploids plants further
  research needed to produce diploid plants.
• Only paternal material conserved but mixtures
  from many individuals could be envisaged.

(Maxted et al., 1997 Hawkes et al., 2000)
24
In situ techniques

• These techniques involve maintenance of genetic
  variation at location where it is encountered,
  either in wild or traditional farming systems.
• As a conservation strategy, is still in its
  infancy and there remain many unknowns.

(Maxted et al., 1997)
25
In situ techniques

• Genetic reserve
• Location, management, and monitoring of genetic
  diversity in natural wild populations within
  defined areas designated for active, long-term
  conservation.

Natural protected area management zone in Turkey
where crop wild relatives are found (www.ipgri.cgi
ar.org International Plant Genetic Resources
Institute)
(Hawkes et al., 2000)
26
In situ techniques

• Genetic reserve

• Advantages
• Dynamic conservation in relation with
  environmental changes, pest and diseases
• Appropriate method to recalcitrant species
• Possibility of multiple target taxa reserves and
  conservation of a diverse range of wild relatives
  

• Disadvantages
• Materials no easy available for utilization
• Vulnerable to natural and man-directed disasters
• Appropriate management regimes poorly understood
• Requires high level of active supervision and
  monitoring

(Maxted et al., 1997)
27
In situ techniques

• On-farm
• Sustainable management of genetic diversity of
  locally developed traditional crop varieties with
  associated wild and weedy species or forms by
  farmers within traditional agricultural,
  horticultural or agrisilvicultural cultivation
  systems.

CIP, on-farm conservation of potato
germplasm (www.cipotato.org)
(Hawkes et al., 2000)
28
In situ techniques

• On-farm

• Advantages
• Dynamic conservation in relation to environmental
  changes, pest and diseases
• Ensures the conservation of traditional land
  races of field crops
• Ensures the conservation of weedy crop relatives
  and ancestral forms.

• Disadvantages
• Vulnerable to changes in farming practices
• Appropriate management regimes poorly understood
• Requires maintenance of traditional cultural
  systems and possible payment of premiums to
  farmers
• Restricted to field crops
• Only limited diversity can be maintained on each
  farm, so multiple farms in diverse regions are
  required to ensure the conservation of genetic
  diversity.

(Maxted et al., 1997)
29
In situ techniques

• Home garden
• Similar to on-farm conservation, involves
  smaller scale but more species-diverse genetic
  conservation in home, kitchen, backyard or
  door-yard gardens.

(Maxted et al., 1997)
30
In situ techniques

• Home garden

• Advantages
• Dynamic conservation
• Ensures conservation of traditional land races of
  minor crops, fruit and vegetables, medicinal
  plants, culinary herbs, etc.
• Ensures the conservation of weedy relatives and
  ancestral forms.

• Disadvantages
• Vulnerable to changes in farming practices
• Appropriate management regimes poorly understood
• Requires maintenance of traditional cultural
  systems, and possible subsidization of farmers

(Maxted et al., 1997)
31
Complementary conservation

• The two strategies should not be seen as
  alternatives or in opposition to one another, but
  rather as being complementary.
• This had lead to the adoption of a more
  holistic approach to conservation. The
  formulation of an overall conservation strategy
  should apply a combination of different
  techniques available, including both in situ and
  ex situ techniques, where the different
  methodologies complement each other.

(Maxted et al., 1997)
32
Complementary conservation
Hypothetical representation of the proportions of
the gene pool conserved using seven different
conservation techniques for different crops.
Orthodox seeds
Forest specie
Root or tuber crop
A seed storage B field gene bank C in vitro
storage D pollen storage E DNA storage F
genetic reserve G on farm reserve
(Adapted from Maxted et al., 1997)
33
Costs
Annual costs of maintaining cassava, wheat and
maize germplasm field gene bank, in vitro and
seed conservation.
(Epperson et al., 1997 cited by Hawkes et al.,
2000)
34
Benefits

• Estimated annual markets for Genetic Resources
  Products

(ten Kate and Lair, 1999 cited by Hawkes et al.,
2000)
35
References
Cited Epperson, J.E., D.H. Pachico and L.
Guevara, 1997. A cost analysis of maintaining
cassava plant genetic resources. Crop Science,
37 1641- 1649. IPGRI, 1993. Diversity for
development. International Plant Genetic Resource
Institute, Rome. Hawkes, J.G., N. Maxted and
B.V. Ford-Lloyd, 2000. The ex situ conservation
of plant genetic resources. Kluwer Academic
Publishers . Maxted, N., B.V. Ford-Lloyd and
J.G. Hawkes, 1997. Plant genetic conservation
the in situ approach. Chapman and Hall. ten
Kate, K. and S.A. Laird, 1999. The commercial use
of biodiversity access to genetic resources and
benefit sharing. Earthscan, London.
36
References
Of interest Dulloo, M.E., L. Guarino, F.
Engelmann, N. Maxted, J.H. Newbury, F. Attere and
B.V. Ford-Lloyd, 1998. Complementary conservation
strategies for the genus Coffea A case study of
Mascarene Coffea species. Genetic Resources and
Crop Evolution 45 565- 579. Damania, A.B.,
1996. Biodiversity conservation a review of
options complementary to standard ex-situ
methods. Plant Genetic Resources Newsletter 107
1-18. International Plant Genetic Resources
Institute (IPGRI) www.ipgri.cgiar.org Centro
Internacional de la Papa www.cipotato.org