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Botanic Gardens and Agricultural Genebanks: Building on Complementary Strengths for More Effective Global Conservation of Plant Genetic Resources

J.M.M. Engels and F. Engelmann
International Plant Genetic Resources Institute (IPGRI)
Rome, Italy


Home | Contents | Abstract | Introduction | Definitions | General Differences Between Botanic Gardens and Agricultural Genebanks | Complementartity Between Botanic Gardens and Agricultural Genebanks | Suggested Strategy For Closer Collaboration Between Botanic Gardens and Genebanks | Table 1 | Acknowledgements |References


Abstract

Traditionally, approaches for plant genetic resources conservation have been largely determined by the availability of storage methods. In most cases, genetic resources have been stored as dried seeds at low temperature (for orthodox seed producing species) or as whole plants in field genebanks or botanical gardens (for vegetatively propagated material or species with non-orthodox seed storage behaviour). Additional techniques have recently been developed, including in vitro conservation and pollen storage. Conservation of genetic resources in situ, i.e. in their natural habitat or in farmers' fields, where they have developed distinctive characteristics, is of major importance for maintaining diversity at the ecosystem level (e.g. forest genetic resources) and for cultivated crops and their wild relatives in the centers of diversity.

The different conservation methods complement each other and should be employed in combination, depending on the biological nature of the species, the infrastructural, technical, administrative and policy conditions at the conservation site while considering the needs and requirements of all stakeholders. Whereas genebanks usually aim at the conservation of genetic diversity within cultivated species and their wild relatives and often specialize in a limited number of species or genepools, botanical gardens usually focus on genetic diversity at the species level and maintain large numbers of different (wild) species with little attention being paid to intra-specific diversity. Therefore, botanical gardens and genebanks are complementary for the conservation of plant genetic resources. Consequently, more adequate coordination and cooperation will be beneficial for safeguarding global plant genetic resources for present and future generations.

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Introduction

The loss of genetic diversity is inherent to evolution and does not lead to major problems as long as nature is able to respond through the creation of new diversity. This process is best illustrated by Darwin's theory on the "survival of the fittest" (Darwin, 1859). However, increased human intervention resulting in irreversible environment destruction, such as deforestation and agricultural developments, is increasingly distorting this "equilibrium" of nature, resulting in an exponentially growing rate of genetic diversity losses exceeding pre-hominid extinction by a magnitude of an estimated 1 to 10,000 (Hurka, 1994). Genetic erosion occurs at three levels: ecosystem, species and intraspecific. This paper is concerned with the focus on species diversity and the within-species diversity.

In the agricultural sector concern about irreversible loss of genetic diversity, especially at the intraspecific level, has led to the establishment of genebanks worldwide since the late 1960s. Genebanks are dedicated to ex situ conservation and facilitation of use of agrobiodiversity. Botanic gardens, on the other hand, have existed as early as the 16th century for a variety of purposes, including education, plant introduction and research. Thousands of taxa are being maintained, increasingly with conservation as a specific goal (Wyse Jackson, 1998).

Considering the urgency and the complex challenges associated with the conservation task at hand, and the very specific and complementary strengths of botanic gardens and agricultural genebanks in this field, the aim of this paper is to demonstrate the advantages and importance of close collaboration between these two apparently independently working institutions.

After defining plant genetic resources the paper will assess general differences between conventional botanic gardens and agricultural genebanks from a conservation point of view. Then, the areas of complementarity are explored and opportunities for collaborative efforts for mutual benefit and leading to improved conservation are described. In the last section, strategies and activities are suggested for closer collaboration between botanic gardens and agricultural genebanks as a contribution to an intensified dialogue.

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Definitions

The Convention on Biological Diversity (CBD), in Article 2, provides the following definitions (UNEP, 1994):

"genetic material" means any material of plant, animal, microbial or other origin containing functional units of heredity.

"genetic resources" means genetic material of actual or potential value.

The International Undertaking on Plant Genetic Resources adopted by the Food and Agriculture Organization of the United Nations (FAO) Conference in 1983 defines "plant genetic resources" as "the reproductive or vegetative propagative material of the following categories of plants:

Thus the International Undertaking, in its focus on crops, covers the full range of related material that may be used in crop development. The Undertaking is overseen by the FAO Commission on Plant Genetic Resources for Food and Agriculture, which, by a Resolution of the FAO Conference, has the mandate to cover "all components of biodiversity of relevance to food and agriculture". In plants, this coverage is implicit in the term Plant Genetic Resources for Food, and Agriculture (PGRFA) which includes wild species used as food or for other agricultural purposes. The International Undertaking is currently being revised, through inter-governmental negotiations in the FAO Commission on Plant Genetic Resources for Food and Agriculture, in harmony with the CBD. Article 3 of the draft negotiating text states that "This Undertaking relates to plant genetic resources for food and agriculture".

Within this wider definition, countries are currently negotiating multilateral facilitated access to the main plants on which food security depends, and in relation to which countries and regions are inter-dependent. The negotiating list currently contains few tree species (coconut is included), but in the context of this paper, forest genetic resources will be treated as an integral part of PGRFA.

In order to include an important additional component of a genetic resource (additional to the biological material per se), i.e. the existing information on the use of the biological material as part of the indigenous knowledge complex, the following working definition is used in this paper:

(plant) genetic resource=biological material + information

Finally, conservation as a conscious and targeted activity needs to be defined in order to provide the right framework for the discussions to follow.

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Conservation of Plant Genetic Resources:

"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 maintenance and recovery of viable populations of species in their natural surroundings and, in the case of domesticated or cultivated species, in the surroundings where they have developed their distinctive properties.

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General Differences Between Botanic Gardens and Agricultural Genebanks

With the ultimate objective of formulating conservation areas where botanic gardens and agricultural genebanks are complementary, it is necessary to first assess the typical differences between these entities. It should be remarked that the conclusions herein are based on "the average" conventional botanic garden, including those with genebanks, and on "the standard" agricultural genebank. Consequently, many exceptions might exist. Furthermore, it should be noted that this "comparison" is made from a clear conservation (and use) standpoint and that only key aspects are being considered.

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Primary Conservation Purposes

The considerable differences between the conservation of germplasm for plant breeding, which is one of the main goals of crop genebanks, and the conservation of samples of species as part of an overall strategy for the survival of those species and the reintroduction in the wild (Heywood, 1991) are decreasing, especially since botanic gardens increasingly also conserve specialized collections which are used by breeders and agricultural genebanks that have become increasingly involved in local germplasm repatriation and restoration activities (SGRP, 1997).

Botanic gardens maintain collections of living plants grown for educational, scientific or economic purposes (Hawkesworth, 1995). In this context, the educational importance of botanic gardens should be particularly stressed, this aspect is well illustrated by the fact that approximately 600 million visitors are recorded every year (Rammeloo, 1998). Furthermore, many botanic gardens are involved in seed exchange with other botanic gardens or research institutes, facilitated by the publication of Index Seminum. The IUCN Botanic Gardens Strategy identified three main objectives of living resource conservation (Hamann, 1987): a) to maintain essential ecological processes and life support systems, b) to preserve genetic diversity, and c) to ensure that the utilization of species and ecosystems is sustainable. Today, botanic gardens are accepting new responsibilities and are designed to be broadly based botanical resource centres (Wyse Jackson, 1998). They are ideal institutions for setting up wild species genebanks with the aim of preserving rare or threatened plants and making the material available for research.

Agricultural genebanks have as their primary objective the conservation of plant genetic resources for use in plant improvement programmes. In general, they provide free access to the collections and conduct and/or promote the generation of relevant information about individual accessions. Whenever possible, material is provided for research purposes and, more recently, conserved germplasm is being repatriated or made available for restoration purposes either in farmers' fields or in nature (SGRP, 1997).

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Main Conservation Approaches

Botanic gardens traditionally maintain their plant material as living collections in the garden. This ex situ approach has more recently been complemented by the establishment of seed banks as illustrated by a survey in 1994 of botanic gardens of which 37% had seed storage facilities (Laliberté, 1997). The increase in seed storage facilities will lead to a diminished need for botanic gardens to grow out their annual species each year. It should be noted that many gardens maintain plant material also as tissue cultures, especially since many of the species they maintain cannot be stored in the form of dried seed at low temperature.

Agricultural genebanks have a tradition of conserving germplasm as dried seed under low temperature in cold store. According to the State of the World report 60% of the reported approximately 6 million accessions are stored at low or very low temperatures; another 8% of the accessions are stored under short-term conditions (i.e. at higher temperature but with humidity control) and about 10% are maintained in field genebanks, in vitro or under cryopreservation. The germplasm kept as in vitro material, including cryopreservation, comprises of approx. 38,000 accessions (FAO, 1996).

Botanic gardens and agricultural genebanks both face the situation that many species do not produce seeds or produce so-called recalcitrant seeds and/or are vegetatively propagated which necessitates a search for other conservation approaches. Usually, these difficult to conserve species are maintained as living collections in field genebanks. Increasingly, these species are being maintained as in vitro collections. In addition, pollen is being used to a limited extent and, more recently, DNA sequences are also being kept in specialized banks (Engelmann, 1997). Since the early 1990s agricultural genebanks have been participating in the conservation of agrobiodiversity on-farm, (Jarvis and Hodgkin, 1998). Similarly, botanic gardens, in cooperation with other bodies, are becoming more and more involved in the in situ management of plant resources (Hawkesworth, 1995; Heywood, 1998). With the significant increase of conservation efforts, cost-effectiveness and efficiency aspects are influencing the conservation approach. This has, among other factors, led to the development of complementary conservation and use approaches in which different available approaches and methods are combined to achieve the most stable and cost-effective conservation effort for a given genepool under locally prevailing conditions (Withers, 1991; Wyse Jackson, 1998)

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Administrative and Legal Perspectives

Botanic gardens have very diverse roles and functions (Heywood, 1987) and also diverse administrative, financial and governance arrangements. Some are privately owned, others are an integral part of a university or operated by municipalities. Until some years ago only a few formal linkages existed with national conservation efforts (Hurka, 1994). Regarding security aspects of the plant material conserved, only a limited number of gardens have duplicated their seed collections for safety reasons, i.e. 24.1% of the long-term, 8.3% of the medium-term and 7.7% of the short-term stored material (Laliberté, 1997).

Agricultural genebanks are usually part of national or international research systems and in most cases are part of the public sector. Most of the national genebanks are part of formal national plant genetic resources programmes. In fact, 74 countries reported having a national programme in place, or being in the process of developing one (FAO, 1996). Because of the foregoing, genebanks usually have well-established linkages with researchers in universities and research institutions, thus facilitating research on the material conserved. Duplication of accessions for safety reasons is part of the internationally agreed standards, but is only actually carried out to a limited extent. Of the approximately 600,000 CGIAR-held accessions 43.8% are stored as safety-duplicates elsewhere (SGRP, 1996). The legal status of several non-CGIAR international collections has not been resolved as yet, but the CGIAR Centres concluded agreements with FAO placing the designated germplasm under the auspices of FAO as part of the International Network of Ex Situ Collections (Hawtin et al., 1997). In addition, as part of the renegotiation of the International Undertaking of the FAO, discussions are progressing to establish a multilateral system in which the designated germplasm is respected as public domain material (FAO, 1998b).

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Plant Material Maintained

Botanic gardens have a strong focus on wild species which are frequently endangered in their natural habitat (Heywood, 1991, 1998; Wyse Jackson, 1998). In the past many European botanic gardens started with the study of medicinal and aromatic plants and built up considerable collections (Heywood, 1998). Gradually, ornamental plant species became en vogue and the gardens often maintained material collected abroad. This function was further strengthened during colonial times when botanic gardens became the introduction and distribution centres for tropical species, predominantly new crops of economic potential (Rammeloo, 1998). More recently, several gardens established specialized conservation collections, usually for research purposes. It has been estimated that the approximately 1,700 botanical gardens conserve up to 100,000 species (Heywood, 1991) and maintain jointly approximately 3.2 million samples (Hawkesworth, 1995). The 152 botanic gardens with genebanks surveyed maintain an estimated number of over 255,000 accessions (Laliberté, 1994). Furthermore, 721 botanic gardens are reported to be associated with herbaria, containing a total of over 80 million specimen (Hawkesworth, 1995). It should be noted that most of the existing collections have been established by botanists and/or specialized plant collectors.

Agricultural genebanks have a clear focus on cultivated species and, more recently, but to a lesser extent, on related wild species. According to the State of the World Report (FAO, 1996) from the approximately 6 million accessions reported to be maintained by genebanks worldwide, which also includes several of the botanic gardens' genebanks, only 15% are wild relatives and/or weedy and wild plant species. Most of the current agricultural genebank collections derived from previously formed breeding collections. Since the 1960s, the latter have been gradually complemented with endangered landraces and wild relatives, predominantly of the major food species. The number of agricultural genebanks and/or germplasm collections grew steadily from approximately 54 at the end of the 1970s to over 1,300 by 1996 (FAO, 1996). It should be mentioned that the number of accessions of minor species, usually named as neglected and underutilized crops, is rather limited, i.e. 7% of the total germplasm holdings (Padulosi, 1998). The majority of the accessions in agricultural genebanks have been collected by plant breeders and, more recently, increasingly by plant genetic resources specialists.

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Genetic Diversity Aspects

Botanic gardens traditionally have predominantly focused on the maintenance of species diversity. It is estimated that as many as 100,000 different species are maintained by all the botanic gardens (Heywood, 1991). Twenty-one selected European botanic gardens with established seed banks hold an average of 1,319 species (ranging from 21 to 7,100) and an average of 3,957 accessions (60 as a minimum and 21,700 maximum). This is an overall average of 3.0 accessions per species. The Royal Botanic Garden, Edinburgh maintains a living collection of 16,782 vascular plant species which are represented by a total of 39,930 accessions (Heywood, 1998), corresponding to an average of 2.4 accessions per species. In the earlier-mentioned botanic garden genebank survey where the 152 genebanks were reported to conserve 255,832 accessions of 92,369 species, the average number of accessions per species is 2.8 (Laliberté, 1994). This rather weak intraspecific diversity is even weaker when the number of individuals per accession is considered.

Agricultural genebanks usually harbour a limited number of species with a considerable amount of accessions per species. According to the State of the World Report (FAO, 1996) the approximately 1,300 genebanks and germplasm collections worldwide maintain a limited number of species and a total of 6 million accessions. Of these, approximately 10% are wild species. The eleven plant genebanks of the Consultative Group on International Agricultural Research (CGIAR) maintain a total of approximately 53 cultivated species (predominantly major food crops) with a total number of accessions of well over 500,000 (SGRP, 1998). In addition, almost 3,000 accessions of wild relatives, weedy plants and forages accounting for more than 87,000 accessions, or 14.7% of the total, complement the CGIAR plant germplasm collections (SGRP, 1998). Total CGIAR genebank holdings consist of some 600,000 accessions (SGRP, 1996) with an average of 7,387 accessions per cultivated species. The largest seed collection of one crop, i.e. rice (Oryza sativa) contains more than 76,614 accessions! However, when considering neglected and underutilized species more than 80% are represented by 1 to 10 accessions per species (Padulosi, 1998). At the accession level, an international standard (Genebank Standards) has been established and agreed that a genetically uniform accession should contain at least 1,000 viable seeds and a heterogeneous accession should contain a significantly higher number (FAO-IPGRI, 1994)

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Information on Individual Accessions

Botanic gardens genebanks and their linked herbaria generally maintain substantial taxonomic data, in particular at the species level and above, as well as information about species distribution. However, reports (Hurka, 1994; Laliberté, 1997; Heywood, 1998) state that the passport data on individual accessions, i.e. data on their precise collecting site, botanical and common genus and species name, etc. are rather limited and/or that a considerable percentage of plants are mislabelled (Hurka, 1994). The availability of such management data is important for internal and external purposes. The amount of information about usages of the material conserved, with some good exceptions such as medicinal plants, is limited or completely missing (Hurka, 1994).

Agricultural genebanks usually pay due attention to the collecting and management of accession-specific data. Unfortunately, many of the accessions which have been transferred from old (breeding) collections to genebanks lack data on their (precise) origin. Management data are critically important for any genebank and, accordingly, such data are usually given high importance. Although highly variable between genebanks, the amount of accession-specific characterization and evaluation data is substantial, especially for the major food crops but varying greatly from genebank to genebank for the other species (FAO, 1996). This is greatly facilitated by the 80 crop-specific descriptor lists which IPGRI has published to date. Genebank curators have traditionally given due attention to genetic diversity distribution patterns, especially after Vavilov's publication of the centres of diversity theory (Vavilov, 1951).

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Complementartity Between Botanic Gardens and Agricultural Genebanks

In the above section, main differences between botanic gardens and agricultural genebanks are described. When considering the overall requirements for an effective and efficient conservation of plant genetic resources from a global perspective it can be concluded that the two conservation "approaches" are very complementary. The conservation strategies are very similar but the species coverage and, to a certain extent the purpose of the collections, seem to be quite different. In this section the characteristics of the complementarity of both approaches will be highlighted from this global perspective. Since most of the strengths and weaknesses have already been addressed in the previous section, only areas of complementarity will be presented for four selected, different but relevant perspectives, sometimes with a clarifying note (Table 1).

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Suggested Strategy For Closer Collaboration Between Botanic Gardens and Genebanks

Accepting the enormous tasks and responsibilities which rest with the global community in conserving the available but partly highly threatened plant genetic resources, and realizing the rather limited contributions individual organizations and institutions can make to ensure that these efforts will be sustainable, some concrete suggestions follow on how botanic gardens and agricultural genebanks can contribute. From the preceding sections it is obvious that the two institutions do have complementary strengths in many areas and these synergies need to be brought to bear on the global conservation effort, as has been recognized in several papers (FAO, 1996; Heywood, 1987, 1991, 1998; Hurka, 1994; Maunder, 1994).

  1. Jointly define rigorous standards for collecting, conservation and documentation practices, including sampling procedures, seed and in vitro storage conditions, viability testing procedures, accession sizes, etc.
  2. Cooperate in the establishment of (a) comprehensive information management system(s), including a common database of accessions maintained (possibly on a regional level).
  3. Agreement(s) on precise species/species categories/genepool conservation responsibilities to avoid duplication and gaps. Possible considerations on a “division of labour” should be based on actual strength, i.e. wild species - cultivated species; global or regional - local wild flora, etc.
  4. Complement each others’ expertise, skills and facilities, i.e. taxonomists - geneticists; education - training; species diversity - intraspecific diversity; in situ and ex situ, etc.
  5. Ascertain the involvement of each entity in planning local/national/ regional conservation strategies and activities.
  6. Cooperate in the resolution of legal questions related to (ex situ) conservation, utilization and exchange of plant genetic resources. Consider the possibility of botanic gardens representatives actively, a) participating in discussions on the revision of the International Undertaking, b) joining the FAO Global System for the Conservation of agrobiodiversity, and c) using similar or the same Material Transfer Agreements (MTAs) and Germplasm Acquisition Agreements (GAAs), etc.

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Table 1. Salient Conservation Features of Botanic Gardens and Genebanks

PERSPECTIVE BOTANIC GARDENS GENEBANKS
  • Genetic diversity
  • wild species
  • species diversity
  • broad species coverage
  • emphasis on endangered species
  • focus on particular geographical flora (recent development)
  • cultivated species
  • intraspecific diversity
  • limited species coverage
  • focus on species of economic potential and/or threatened by genetic erosion
  • focus on genepools and "national" (unique) genetic diversity (especially since CBD)
  • Socio- economic
  • importance of (environmental) education of broad public
  • research and recreational function
  • funding from local, regional and/or public sources
  • linked to use for crop improvement (breeding), etc.
  • contributing to development and food security
  • funding usually from public sector (predominantly Ministries of Agriculture)
  • Academic
  • focus on taxonomy
  • educating the broad public
  • knowing the flora (local or specific to a particular geographical area)
  • focus on genetics
  • training technical people
  • knowing genetic diversity in genepools of cultivated species
  • Conservation
  • living collection management
  • species diversity maintenance
  • species (specimen) survival
  • seed collection management (predominantly)
  • within-accession and within-species diversity management
  • maintenance of genetic integrity


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Acknowledgements

The assistance and contributions of Brigitte Laliberté and Hareya Fassil in the preparation of this paper are duly acknowledged.

References

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