From the early beginnings of agriculture, germplasm resources have been selected, exchanged, collected, and preserved. Over time, cultivation of crops and farm animals has yielded landraces and breeds that are specific to various regions of the globe. Artificial selection by the farmer and natural selection by the elements developed a combination of genetic traits to meet the agricultural needs and climate and soil conditions that characterized each region. While many landraces of crops and breeds of animals can be traced back to their wild relatives, and even to their geographic centers of origin, there are others where the path of migration or genetic refinement to an agriculturally important genotype remains speculative.
In the past as well as today, the management of germplasm resources reflected a combination of the technology available and the particular uses of these resources. The age of exploration that erupted in the fifteenth century with the discovery of New World resulted in exchanges of agriculturally valuable germplasm to and from every traveled region of the globe. Many of the exchanges during this great age of germplasm explorers were pivotal to the course of human history. The linkage of human slavery in the Americas to sugarcane and cotton and the role of the potato in the population explosion in Europe and consequently the industrial revolution are well-known examples (Harlan, 1992; Heiser, 1981). In addition, the accidental introduction of old pests, which were carried along with exchanged crops, and the appearance of new diseases or pests, which attacked introduced crops, resulted in quarantine measures.
Since the beginning of the twentieth century, the science of genetics has greatly escalated the speed and accuracy of breeding new genotypes. Earlier, in the 1860s, the Austrian Abbott Gregor Mendel, working with peas in his garden, discovered that most genetic traits follow mathematically predictable patterns of inheritance. His discovery permitted a new level of precision in genetic selection. More recent developments, since the 1950s and the discovery of deoxyribonucleic acid (DNA), allow scientists to identify, isolate, and manipulate individual genes at the molecular level. These developments continue to drive major advances in the technologies available to cull and manage germplasm resources. Genetic tools have produced an explosion in the rate of artificial selection and breeding for crop improvement, which is largely responsible for the manyfold increases in agricultural yields during this century. For example, U.S. corn yields have increased from 20 bushels per acre in the 1930s to 120 bushels per acre in the 1980s. About 50 percent of the increase in yields is due to genetic gain (Duvick, 1992). The ever-increasing pace of crop breeding has greatly refined and enhanced the value of germplasm collections. Yet as the high-yielding, highly selected varieties become utilized in agriculture around the globe, they threaten to displace their ancestral landraces and breeds.
AN AGRICULTURAL ENDOWMENT
Selecting, collecting, exchanging, and preserving germplasm resources are not new activities or issues. They are in fact as old as agriculture itself, as old as our knowledge of growing crops for food. But what is new, and pressing, is how to make national and international decisions about managing these activities for the future.
Circumstances throughout the world are changing at a rapid rate. The pace of scientific and technological developments has increased and, with it, the political and material demands of societies worldwide. People's needs for food, medicines, housing, land to cultivate, and the other natural resources of the earth—and their concern for having a voice in decision making about their needs— are increasing.
The natural environments of the earth are rapidly becoming managed— or mismanaged— ecosystems. The threats to biological diversity and the challenge to preserve and manage these natural endowments are well recognized (Wilson and Peter, 1988). The issue of global genetic resources is not merely the more clearly defined processes of collection, exchange, and preservation. The issue involves a dynamic system, an endowment, that requires management. And at
this time, it is a system that is experiencing scientific and social pressure that often push from opposite directions.
This genetic resources endowment to a small extent has been captured as stored seed, in a variety of institutions throughout the world, that can be planted and grown out. But more broadly, a number of tangible and intangible components of this endowment require persistent attention overtime. They include seeds and propagules of plants or sperm and embryos of animals that cannot be held in cold or long-term storage; the special collections and experience represented by individuals throughout the world who have devoted their careers to the germplasm of particular species; the exchange of knowledge as well as germplasm resources that takes place formally and informally; and the continual natural selection in an Amazonian forest, grassland reserve, or cultivated area that persistently reshapes genotypes.
Similarly the continuous artificial selection practiced by breeders to create new cultivars or by farmers to emphasize special traits in a landrace or breed further refines germplasm resources.
Global genetic resources are not static. They constitute a living, changing, diverse system that can best benefit humankind when thoughtfully managed. Without proper management of these resources, many of their riches— the keystones to our ability to produced food—will be lost. Once lost, genetic resources cannot be regained.
Plant and animal germplasm is an agricultural endowment that offers the dividends of improved varieties and breeds of food crops and animals and increases in yield. Sound management practices can ensure that the "capital" derived from this endowment will not be squandered.
In this report, the Committee on Managing Global Genetic Resources: Agricultural Imperatives summarizes the status of global genetic resources. It assesses genetic vulnerability, the condition that results when a crop is uniformly susceptible to a pest, pathogen, or environmental hazard as a result of its genetic constitution, thereby creating a potential for vulnerability or even disaster. It describes the importance of in situ conservation of genetic resources, and details the science of collection, use, and management of these resources. Further, the report discusses policy issues relating to quarantine; proprietary rights; and conflicts over ownership, management, and use. It also presents a basis for assessing the economic value of genetic resources and evaluates existing national and international genetic resources programs.
This report structures the foundation for managing global resources for the future. The challenge to scientists and farmers alike is to be able to respond to the continuously changing landscape of modern agriculture. The challenge to policymakers and national leaders is to ensure that the genetic resources endowment is managed wisely to serve society, now and in the future.
THE NEED FOR GENETIC RESOURCES
The genetic components of crops today are based on landraces, slightly improved and obsolete varieties, recently developed breeders' lines, and wild species. As biotechnology enhances the ability to move genes among distantly related species, the breadth of species diversity that constitute a crop's genetic resources will increase. For livestock, genetic resources encompass the wide variety of breeds and types found around the world.
The rapid spread of improved crop varieties throughout the world
has replaced many of the genetic resources essential to their continued improvement. Landraces, selected over decades in the presence of a wide range of pathogens, have proved to be important sources of genes for such traits as disease and pest resistance or drought tolerance. Thus, the conservation of traditional landraces as part of a crop's genetic resources has became imperative.
Nonetheless, landrace replacement is only one source of risk to the world's genetic resources. Population expansion, urbanization, deforestation, and pollution and destruction of the environment also threaten much of the world's biological resources and their diversity. As a countermeasure, many national and international collections have been established with the intention of rescuing and conserving them for future use. Some, such as the rice collection of the International Rice Research Institute (IRRI), have captured a major portion of the total genetic diversity of a particular crop. Other notable collections include those for wheat, maize, soybean, potato, tomato, sorghum, legumes, and many of the world's grain, fruit, vegetable, fiber, forage, and industrial crops. However, despite efforts in germplasm collection and maintenance by the commodity-oriented centers of the Consultative Group for International Agricultural Research (CGIAR), CGIAR's international Board for Plant Genetic Resources (IBPGR), the Food and Agriculture Organization (FAO) of the United Nations, and many national genetic resources programs, much work remains for this broad and difficult mission.
The better managed and more comprehensive a collection, the more valuable it is to researchers who must locate needed materials within it in an efficient manner. The likelihood that any single accession of a major collection has an essential gene or gene combination is low and, thus, it may have little value by itself. The value is not in individual accessions, but in the entire collection as a source of the crop's genetic diversity. The value of genetic resources collections is illustrated by increases in yields in rice productivity in India between 1972 and 1984. Varieties that were improved by means of genetic resources collections contributed more than one-third of these gains during this period.
An accession of unimproved germplasm of unrecognized potential is of value only when it is useful in an improvement program. Accessions that have no value today may suddenly have strategic value tomorrow. Unimproved genetic resources are not traded in markets in a manner similar to improved breeding lines or livestock breeds. Thus investment in a conservation program must be based on its potential to yield a benefit in the future. Whereas the developed nations are most able to support such conservation investments,
the developing countries are where the greatest diversity of crop genetic resources exists. This disparity, given inequality among nations and the limited financial resources of most developing countries, has led to calls by many in the developing world for compensation from those who have collected genetic resources from another country and used these resources to establish improved varieties.
ACCESSING GENETIC RESOURCES
In a broad sense, conserving genetic resources, either in collections or within reserves or other natural areas, preserves access to them. Efforts to conserve the biological diversity of the world's tropical forests, for example, save many as yet unidentified species that may have potential utility. Access to well-maintained stocks of germplasm resources of agricultural species is required by researchers and others who may need specific resistance factors, breeding lines, species, or populations for use in study or breeding. Ease of access depends on both the technology and practice of germplasm use and the policies and laws that affect exchange of genetic resources between researchers, institutes, or nations.
The Role of Science and Technology
The most extensive systems for managing genetic resources exist for agricultural crops. They are supported by a considerable body of scientific information and technology. Emerging biotechnologies are also expected to lead to more information on existing collections and to increase the efficiency and precision of germplasm use.
In Situ or Ex Situ Conservation?
Many wild plant genetic resources can be conserved where they occur naturally (in situ). Although domesticated materials can sometimes be maintained where they were originally selected, unless there is an incentive to continue planting them, they tend to be replaced by modern cultivars or lost due to human neglect.
Ex situ conservation occurs outside the species' natural environment. It can include field plantings; seeds or pollen held in cold storage; tissue cultures; or seed, pollen, or tissues held under cryogenic storage (-150° to -19°C). Most major collections of seed. Genetic Resources in ex situ collections are often readily accessible to breeders and scientists. They are relatively secure from loss through future
displacement, environmental damage, pests , or disease, although they are separated from the dynamic evolutionary forces that shaped them.
In situ, conservation also preserves germplasm resources against loss, but in situ materials are often less accessible for breeding or research because they are usually not well characterized and studied, and because seeds or propagules may not be generally available. However, in situ collections may preserve as yet unrecognized or rare genetic traits that could be lost if only selected samples were preserved. For agricultural crops, ex situ methods are the primary means for conservation. Ex situ collections provide breeders or other researchers more immediate access to characterized accessions, which may include improved varieties and breeding lines.
Microorganisms are conserved almost exclusively ex situ. Some 18,500 species are estimated to be held in world culture collections that are part of an international network for their management, distribution, and utilization. These collections are important to the agriculture, food and beverage, and pharmaceutical industries and as research tools.
Managing the Numbers
The growth of genetic resources efforts had led to several large ex situ collections (Tables 1 and 2). However, the extent of genetic coverage within a crop and the level of care to preserve the collection vary markedly. Although large collections can improve the chance that most genes are captured, their sizes make it difficult to maintain viability, regenerate aged seed, document accessions, and screen for particular traits. Furthermore, long-term conservation, evaluation, and characterization become increasingly difficult as large collections increase in size. Data storage and retrieval methods and management tools, such as the use of core subsets, can give users more direct and selective access to large collections. An ideal core subset within a collection would contain a range of accessions that represents, with an acceptable level of probability and minimum redundancy, much of the genetic diversity of the crop species. Typically, it would consist of no more than 10 percent of a whole collection.
Selecting too few samples for a collection can leave important alleles uncollected. Considerations for determining how much to collect should include the mating system of the population (whether it is outcrossing or inbreeding) and its mobility (by dispersal of pollen or seed and the nature of the samples). In general, the less frequently a particular allele occurs in a population, the greater the number of plants that must be sampled to collect it. Samples from no
TABLE 1 Conservation Status of Major Crops
more than 5 plants are adequate to collect alleles present locally at frequencies of 75 percent, whereas 200 or more plants must be sampled to secure alleles present at frequencies of 1 percent. Generally, sampling more sites is more effective at capturing genetic variants than is sampling more plants within a site.
Genetic diversity is usually not dispersed uniformly. Empirical studies of the slender wild oat revealed that genetic variation is correlated with environmental factors such as rainfall, temperature, slope, exposure, and soil type. Studies of variation in maize, a domesticated outbreeding species, show similar variability. Collection sites must therefore represent as many environments as possible and, in the case of domestic species, as many cultural environments as possible.
Predicting which accessions in a collection are likely to contain particular genetic traits is aided by information on the collection. The more information available, the more easily a breeder or researcher
can locate likely accessions. Three kinds of information about accessions are required: passport data, which relate to the ecogeographic origin of the accession; characterization data, which describe appearance and structural traits that are highly heritable and generally unaffected by differing environments; and evaluation data, which involve the more variable qualities of an accession, such as relative yields, disease resistance, or fruit quality. The latter data are of most interest to a breeder; passport data are essential for management,
TABLE 2 Estimates of Germplasm Holdings in the Five Largest National Plant Germplasm Systems and Major International Centers
use, and assessment of a collection's quality. In general, gathering passport and characterization data is part of collection management. Evaluation is usually done breeders or specialists, and, although location specific, this information should also become a part of the accession's record.
Unfortunately, capturing passport, characterization, and evaluation data has often received little attention. Detailed evaluation data are lacking for most of the world's collections, and even passport information is often surprisingly incomplete and unusable.
Regeneration: Essential but Overlooked
The growing out of collection samples to increase seed and maintain their viability is another important activity. Plants grown from seed accessions are vulnerable to environmental stresses that can produce unique selective pressures. Strategies for regeneration must preserve the original integrity of the sample to keep the regeneration process itself from becoming a source of genetic loss.
Too often regeneration is poorly considered in the planning of germplasm management activities. Problems can arise when the magnitude of the task exceeds available resources, as well as from inadequate consideration of the potential biological difficulties. Growing accessions too near one another, or without using isolation methods such as cages or bags to prevent cross-pollination, can result in unintended hybridization and loss of genetic integrity. If accession is self-pollinating, as are many beans, there may be little concern. However, species pollinated by insects, which may carry pollen between widely separated plants, can prevent serious difficulties. Typically it is regeneration capability that ultimately limits the effective size of the collection. There is little future in amassing large collections that die in storage due to the inability to regenerate. Thus, planning should begin with regeneration requirements.
The Role of Biotechnology
Biotechnology influences germplasm conservation in at least four ways. First, it provides alternatives, such as plant tissue cultures, for conserving organism. Second, modern techniques may simplify quarantine requirements by providing better tools, such as DNA test for the presence of viruses in plants or seed stocks. Third, the application of molecular techniques may eventually address problems of using germplasm. For example, DNA probes can be used to screen germplasm accessions for the presence of particular genetic sequences
that encode specific traits. Dot blot tests can use DNA probes to detect the presence of genetic information from rye in wheat breeding lines. Fourth, biotechnology itself can lead to increased demand for germplasm and conservation services because it makes them easier to use. For example, the numbers of genes that have been isolated, cloned, and sequenced increase daily and represent a resource of considerable scientific and commercial value.
A direct application of biotechnology to germplasm use is the transformation of DNA to bring about directed genetic changes. Transformation has been carried out in bacteria, fungi, algae, and more than 30 species of plants and in nematodes, insects, fish, and mammals including several species of livestock. For the past several years field trials of genetically engineered crop plants, carrying foreign genes for resistance to herbicides, viruses, and insects, have shown in the potential of transformation as a breeding tool.
Exchange and Ownership
The larger portion of accessions in collections today comes through exchange activities. International and national collections have been
used to restore genetic resources lost through war, or natural disaster. There are, however, policy and legal constraints to exchanging genetic resources. For example, in an effort to protect national agriculture and prevent the spread of pests and diseases, nations may limit exchange through the use of quarantine restrictions. Restrictions have sometimes been used to limit trade rather than to protect crops; such economic or political restrictions can be major limitations for germplasm exchange. More controversial has been the application of ownership rights to germplasm.
When animal or plant genetic resources are brought into a country they may carry pests or pathogens that could damage agriculture. Cassava bacterial blight (Xanthomonas manihotis) for example, is believed to have been introduced to Africa and Asia from tropical America by way of infected planting material. For animals, rinderpest, an acute infectious disease and a significant problem for some countries of sub-saharan Africa, was introduced from Central Asia near the end of the last century. In rinderpest epidemics, mortality ranges up to 90 percent.
Quarantine is designed to exclude potential sources of pest or pathogens from entry. It is typically a government responsibility, and nations differ as to how it is implemented. Quarantine practices generally prohibit exotic pathogens, pests, or parasites. They attempt to contain, suppress, or eradicate pests and pathogens. Government quarantine agencies may also assist exporters in meeting the quarantine requirements of importing countries.
When quarantine regulations require delay of importation or exclusion of imported germplasm, they may be viewed as restricting access to genetic resources. In the United States importation of Prunus (stone fruits such as apricots, plums, and almonds) germplasm can be delayed 10 years or more while samples are tested for the presence of viral pathogens. Some nations protect themselves by forbidding the entry of designated species. Biotechnology promises powerful tools for rapid disease screening of imported materials and may help to reduce these delays. Regional and international cooperative efforts to assemble and disseminate information about the distribution of pests and diseases are also important to international quarantine. Close cooperation between germplasm experts and those charged with implementing quarantine regulations can greatly improve access to genetic resources.
Proprietary protection, in the form of patents, plant variety certificates, or copyright, for plant genetic resources has become a divisive issue that fear may restrict access to plant genetic resources. Some developing countries are concerned that they have reaped few of the monetary benefits that have resulted from the use of their germplasm to produce modern cultivars. However, the rise of biotechnology has engendered the expectation that the developers of new crop varieties— whether breeders, biotechnologists, or industry—must be assured of a fair return for their investment. These issues have been debated in forums such as the FAO commission on Plant Genetic Resources, the Keystone International Dialogue on Plant Genetic Resources, the Uruguay round of the General Agreement on Tariffs and Trade negotiations, and the 1992 United Nations Conference on Environment and Development (UNCED) in Rio de Janeiro.
Apart from proprietary protection, several countries have limited access to germplasm that may be of particular national value. For example the export of germplasm of coffee, black pepper, rubber ( Hevea) , soybean, and tobacco is restricted by selected countries. As debate over the value of unimproved genetic resources and wild species has escalated, some nations have restricted collectors' access to germplasm.
The geopolitical debate over plant genetic resources can be illustrated by the extreme positions. One, widely held in the developed world, is that all undeveloped genetic resources, including wild species, primitive landraces, and traditional cultivars, are public goods and should be freely available to all without restriction. Inbred lines, new cultivars, and other forms developed from these materials and protected by patents or plant breeders' rights should not be freely available to ensure that those who invested in their development receive a fair return. The contrasting view, held in parts of the developing world, is that these latter materials should be freely available, without proprietary restrictions, since they were largely developed from materials that originated in the developing world. This view has been reinforced by the suggestion of some form of "farmers' rights" to reward and recognize the contribution of developing world farmers toward the development and preservation of crop plant landraces. Discussions on international genetic resources, such as those sponsored by the Keystone Foundation, Keystone, Colorado, have led to agreement that compensation should come from an international fund, but the mechanisms for supporting it or distributing its proceeds remain to be developed.
Until the early 1990s, there minimal impact of intellectual
property rights— or, more fundamentally, of the increased value that biotechnology had given to genetic resources— on access to these resources. In the early 1990s, however some developing nations saw these resources as one of their strongest bargaining chips in dealing with the developed world. Representatives at UNCED adopted the Convention on Biodiversity on June 5, 1992; the United States signed the convention on June 4, 1993. This convention, which will be a binding legal document, gives national governments the authority to control access to genetic resources. It is, therefore, likely that the era of free and open exchange of agricultural germplasm will soon be over.
Germplasm is one of the world's fundamental resources. Management of genetic resources has moved from being the concern of a few to becoming a vital interest for all nations, since it is vital for the support and development of every nation's agriculture. Neither genetic resources nor the means to conserve them are spread evenly over the globe. Wise and effective management requires broad international cooperation.
Effective programs for managing and using genetic resources are essential for national agricultural health and food security. However, their cost is clearly beyond the capacity of many nations. It is both impractical and unnecessary for each nation, including the United States, to hold complete collections of all important crops and species. Regional associations that pool financial and technical resources can provide the benefits of genetic resources programs while making the best use of limited funds. The international agricultural research centers hold large global collections that can service many national and regional requirements. Adequate financing and suitably trained professional and technical staff are also needed.
While the primary task of using genetic resources rests with individual nations, there are compelling reasons for developing international cooperation in management. Disparities in both the distribution of genetic resources and the financial and technical resources necessary for their management can be addressed through a global system of cooperation that provides benefits to all.
To be effective, a global system must ensure the security of its collections by providing financial support and enforcing rigorous standards. Although many national and international organizations promote the conservation of food crops, no coherent international program has yet emerged to provide a system of funding and coordination that ensures continuity.
International cooperation has been developing through the joint and separate actions of the FAO, most recently through its Commission on Plant Genetic Resources, the IBPGR, and the Keystone germplasm conferences. Questions of germplasm ownership and the distribution of support for national and international efforts have complicated efforts toward more cooperation. Another issue is the degree of authority that an international organization can exercise over the collections of cooperating nations.
International agreements and national policies are major hurdles for developing strong global cooperation. While the debate goes on about legal and effective ownership, genetic erosion continues to take place inside and outside germplasm banks and nature preserves, notably in the developing world, which harbors most of the world's genetic resources. It is in the interest of all that these vital natural resources are adequately conserved and made accessible.
LOOKING TO THE FUTURE: RECOMMENDATIONS
Genetic diversity provides the raw materials for the technology of plant breeding and crop improvement. It is also one of the first lines of defense against serious crop loss in agriculture. Much of the germplasm used to develop today's crop plants would have been lost forever had it not been for the collection efforts of the past, safekeeping of germplasm in public facilities, and availability to any investigator.
The following paragraphs include the committee's principal recommendations. More details and additional recommendations are given in the chapters of the report.
Managing Crop Vulnerability
Crop vulnerability is a measure of the susceptibility of a crop species to catastrophic decline in its production. Although losses often result from drought, severe storms, floods, or other environmental stresses, they can also be greatly aggravated by biologic stress, such as insect infestation or pathogen infection. Genetic vulnerability results when an organism lacks genes that enable it to withstand
an environmental or biological stress or when its genes confer susceptibility to a pest, pathogen, or natural stress.
The peasant farms of traditional agriculture are less vulnerable to catastrophic loss because they grow a wide variety of plants under diversified farming. Many of these plants are landraces grown from seed passed down from generation to generation and selected over the years to produce desired production characteristics. Landraces are genetically more heterogeneous than modern cultivars and can offer a variety of defenses against vulnerability. By contrast, a pest or pathogen has a much less difficult barrier to breech when it encounters a genetically uniform modern cultivar grown under continuous monoculture over wide areas. Consequently, today an entire crop could be attacked and seriously damaged or even destroyed.
Crop vulnerability is not a problem that once addressed is no longer a concern. Rice varieties released by IRRI illustrate the potentially transient nature of breeding success. In 1966, IRRI released the first of its new, short stature, high-yielding varieties, IR-8. Only 3 years later, in 1969, a virus epidemic seriously reduced yields and a newer variety, IR-20, was released. This fell prey to yet another virus and an insect, the brown planthopper (Nilaparvata lugens). It was replaced in 1973 by IR-26. A new genetic variant (biotype) of the brown planthopper that could successfully attack IR-26 subsequently arose and so IR-36— resistant to this new biotype—was released. Rice production in Asia once again rose dramatically. Notwithstanding, yet another biotype of the insect necessitated the release of IR-56 by 1980. And so it goes. Each new release is the result of years of research and breeding.
In the early 1970's, a major epidemic of southern corn leaf blight occurred in the United States and prompted a report of the National Academy of Sciences. This report recognized the potential for the rapid spread of pests or pathogens through the highly uniform, genetically vulnerable fields of modern U.S. agriculture (National Research Council, 1972). Since that time many highly developed crop varieties and livestock species have spread around the world. Despite remarkable increases in agricultural production and the growth of programs for collecting, managing, and using genetic resources, significant tasks still confront the world community. For example, researchers need to assess the genetic vulnerability of currently grown crop varieties.
Diversity in wheat and maize has increased in the United States since 1970, but diversity in rice, wheat, and maize in developing countries has decreased. Landraces are being replaced by modern high-yielding varieties. Breeding and extension programs in many developing countries are not prepared to react rapidly to major epidemics.
Thus, when yields of varieties decline, farmers may find that replacements are not available or transient in durability.
The challenge to scientists and farmers alike is to be able to respond to the continuously changing landscape of modern agriculture. To do so requires a long-range effort that constantly seeks new genetic resources and incorporates new genes or cytoplasms for developing future livestock breeds and crop varieties. Modern biotechnology promises even greater precision to scientists in manipulating crop and livestock genomes. However, the need to germplasm collections as resources for genetic diversity will continue to be crucial importance for plant improvement.
The potential for crop vulnerability must be nationally and globally monitored.
International centers that distribute breeding materials to national programs may disseminate germplasm possessing similar genetic profiles to many scientists. In Asia, many rice varieties are tailored to local conditions, but a large majority share a common semidwarfing and maternal parentage. Thus the potential exists for all of them to possess genes that might confer susceptibility to an as-yet unimportant pest or pathogen.
The extent of food crop vulnerability can most easily be estimated by correlating data on the acreage of major cultivars, the races of pests and pathogens, and the extent of genetic uniformity for resistance or susceptibility. However, reduction in public funding for agricultural research have severely diminished capabilities for monitoring crop vulnerability, even in the developed world. As a consequence important survey information is no longer gathered.
A wide range of genetic and agronomic strategies should be employed to minimize crop uniformity and consequent susceptibility.
Genetic strategies that enhance stability include the planting of multilines, varietal mixtures, and relay plantings of distinctly different genotypes. A multiline is a mixture of lines with different genes for pest or disease resistance that have a common varietal or genetic background. A varietal mixture contains several different varieties, usually with dissimilar genetic backgrounds, that are selected to ripen for harvest at the same time. They may differ not only in pest and disease resistance but also in their tolerance of extremes of temperature and humidity. Relay plantings impose deliberate local or regional diversity of varieties, both in space and time, to avoid widespread genetic uniformity. Thus adjacent fields, or regions, are planted to varieties with different resistance genes. Spring and winter forms
of the same crop are chosen to avoid using the same resistance genes in order to prevent the development of pathogen races that survive on one crop and attack the following one (the green bridge effect). These strategies require a diversity of genetic resources for their implementation.
Modern agricultural practices include monoculture in combination with fertilizers and herbicides, and often with fungicides and insecticides, to achieve high yields. The stability of traditional farming systems is due in part to the mix of crops they contain, cropping patterns, and times at which crops are planted. In recent years, there has been a growing interest in agricultural systems that mimic natural ecosystems. Alternative agricultural strategies, such as crop rotation, modified tillage practices, and integrated pest management can help provide stability of production over time.
Management and Use
Agricultural production has increased dramatically since the 1960s. India, a country many in the 1960s advised was beyond help, not only produces food sufficient for its population, but became a net exporter of grain. An essential element of such successes was the development of new, high-yielding crop varieties that enabled dramatic increases in agricultural production. Central to the development of these and other high-yielding varieties are breeding programs supplied with broad arrays of genetic diversity. The magnitude and importance of these programs, coupled with the globally increasing need for food, underlines the urgent need for effective conservation, management, and use of the world's genetic diversity.
Unique, endangered wild populations that have present or potential value as crop genetic resources should be conserved in situ.
In situ conservation preserves evolutionary and adaptive processes. While many calls have been made for increased in situ conservation, few efforts are specifically directed toward crop genetic resources. Conservation of the maize relative, teosinte, in Mexico and a study of in situ genetic relationships in a wheat relative, Triticum dicoccoides in Israel are notable exceptions.
The capacity to regenerate seed accessions when needed should be an major determinant for limiting the size of germplasm collections.
The timing and extent of regeneration efforts may be determined more by the availability of resources than by the need to preserve genetic integrity. If not performed with adequate scientific oversight,
regeneration can lead to changes in the genetic makeup of the accession (genetic drift), contamination, or loss. These effects are compounded over successive cycles. The need to minimize the number of times accessions in collections are regenerated has prompted the use of techniques such as long-term cryogenic storage. Unfortunately, the capacity of collections to support genetically sound regeneration of their holdings is rarely considered when they are assembled.
Core subsets be identified for large collections to aid management, evaluation, and use of accessions.
The aim of identifying a core subset is to facilitate collection use. A breeder may begin a search for a particular genetic trait, such as disease resistance, by first examining and testing the core subset. If the trait desired is found in a part of the core, then other accessions from the same ecogeographic region or with similar characteristics could be examined.
Core subsets also have advantages for curators. Accessions in the core subset would receive priority in evaluation and characterization, so that in time many more traits would be evaluated for all of the core samples than would be evaluated for other samples. In this way, curators could better use a limited budget to promote the distribution of information and material and, hence, facilitate use of the entire collection.
The principal disadvantage of the core concept is the possibility— or indeed the probability— that the remainder of the base collection would erode away and disappear from neglect or, alternatively, would be seen by some administrators as being of less value and therefore dispensable in the interests of economy. Under the core concept, the entire base collection serves at least two important functions: (1) as a back-up collection to be screened if needed variation is not found in the core subset, and (2) as a source of additional diversity when many different genes are required for the same trait, as in breeding strategies for disease and pest resistance.
Several practical problems must be overcome before the core concept can be fully implemented. One is establishing the appropriate size of a core subset and defining its composition so that it contains a representative sample. Although they should be selected to represent the diversity of the main collection, core subsets are unlikely to capture all of the genetic diversity within all accessions. It is probable that if 10 percent of the accessions in a collection are assigned to a subset, no more than 70 percent of all the available alleles will be included (National Research Council, 1991a). Thus, the rest of the collection will continue to serve as a source of diversity similar to
that in the core, but which results from different genes or alleles. This larger portion may also serve as a resource for genetic traits not captured in the core subset.
Core collections can be used to develop priorities for evaluation and acquisition, but without the construction or establishment of separate collection facilities. The identification of cores does, however, require a basic amount of information about accessions. Minimally this should be the passport data regarding the origins and environment of the accession. Such information is essential to linking core subsets to the potentially wider genetic diversity of the entire collection. A first step in identifying cores, therefore, is the recording of basic passport information about each accession in a collection.
Redundancies within global collections should be minimized.
The costs of eliminating duplicates within a collection usually exceeds the benefits derived from such an effort. Characterization technologies, such as isozyme or restriction fragment length polymorphism analysis, are still too costly for routine germplasm bank use. For many collections, the gains in efficiency from a reduction in duplicate accessions would be modest.
Greater gains in efficiency could be achieved by reducing duplication between collections to that necessary for insurance against catastrophic loss and allow a reasonable degree of accessibility. This is difficult to achieve, however, because it requires a high level of cooperation and coordination among national and international germplasm banks. For countries with economic dependence on particular crops, germplasm collections have strategic importance, and large collections are seen as protection against an uncertain future. This insurance is especially relevant in light of controversies surrounding ownership and control of crop genetic resources.
The limited scope for reducing collection size by eliminating redundancy within and among germplasm banks has led to proposals for improving the management, characterization, evaluation, and use of collections. Use of the new tools from biotechnology and information management will help to minimize duplication. Many problems of duplication would be solved if passport data were adequately obtained and maintained.
Programs of genetic enhancement should be developed to make diverse germplasm resources useful to crop breeders.
Genes are the building blocks of crop and livestock development. Genetic alterations to wheat and rice have improved harvest indices by creating shorter plants that devote more of their photosynthetic
products to grain production. A particular gene may make a plant resistant to a particular pest or disease. Breeders use such plants as sources of traits, such as disease resistance, for the crops they study. Germplasm resources also enable breeders to introduce substantial amounts of new genetic information from untapped sources through recombination.
Within the spectrum of variants comprising the genetic diversity of a crop are accessions that may contain a useful genetic trait, such as resistance to a particular disease or insect. However, such accessions are typically unimproved landraces or wild species that exhibit lower yields and poorer quality along with traits of interest. Breeders may be reluctant to use such an accession in breeding programs because it will require extensive backcrossing to more desirable cultivated forms, and such crosses may only be achieved with difficulty. Thus, prebreeding, or germplasm enhancement, moves desired traits into a more suitable genetic background and is frequently essential to using genetic diversity.
For example, resistance to eyespot disease (Pseudocercosporella herpotrichoides) in wheat is available from wild goat grass (Aegilops ventricosa). However, this species cannot be crossed directly with cultivated what (Tricum aestivum) but must be crossed with another species compatible with both. The process is time consuming and difficult. Also goat grass seed heads shatter and scatter their seeds as soon as they are ripe. In such cases prebreeding is essential to place the resistance gene in a manageable and useful background.
Germplasm collections must at a minimum make available passport information for the materials they hold.
Collections must be well documented to allow rational and efficient searches for accessions with specific genetic traits. Unfortunately, even passport information, which includes the location and general environment where the sample originated, is often unavailable. This basic information would allow breeders to identify those accessions most likely to possess selected genes. Characterization data as well as passport information must receive greater emphasis from plant explorers, germplasm bank managers, and curators. Conversely, plant breeders can make an important contribution by supplying evaluation data to the accession records.
Technology Development and Research
Research has led to technologies for the long-term storage of germplasm, as well as for its rapid and efficient use. In situ conservation,
a method widely recognized as valuable for wild species, could benefit from better understanding of the biological and ecological processes affecting populations. Several important crops cannot be held in long-term storage because of their incompatibility with available methods. Finally, the emerging molecular technologies promise to provide powerful new tools for managing, using, and exchanging germplasm.
Research is needed to elucidate the components for establishing viable and genetically diverse populations of wild species.
In situ conservation areas must preserve the genetic structure of the target species. This preservation requires consideration of the extent of genetic variation within the species that is present in an area. Multiple sites may be required to capture genetic variation associated with adaptation to different soil types, humidity, exposure and so on. However, effective in situ conservation of this genetic diversity is only possible when there is information on the genetic structures of populations and species. Populations conserved in situ should also be large enough to be self-regenerating and to minimize loss of rare alleles. Since the costs of in situ conservation of large populations can be high, some international cost-sharing may be required.
Research is needed to apply in vitro culture and cryogenic storage methods to a broad range of plant and animal germplasm.
In vitro tissue cultures could be used to preserve species that cannot easily be kept as seeds. For some species, especially those that are propagated as clones, this technique may be more efficient and less expensive than maintaining whole plants in field culture. Sterile cultures also are protected from the diseases and pests that threaten field-grown plants. They also can be useful for exchanging and distributing some clonally propagated germplasm.
The storage of seeds or tissue cultures of cryogenic temperatures in liquid nitrogen could preserve plant germplasm for far more than 25 years. The method is not as well developed for plants as it is for semen and embryos of some livestock species. In general, small seeds that are known to withstand freezing temperatures and long-term storage (orthodox seed) can be maintained in liquid nitrogen.
Biotechnology research efforts should focus on developing enhanced methods for characterizing, managing, and using genetic resources.
Rather than obviating the need for germplasm collections, biotechnological innovations heighten their utility. For the molecular
biologist, as well as the breeder, these collections are the raw material from which to draw diverse new genes. The rapid development of DNA sequence data banks, plasmid libraries, and cloned DNA fragments have in turn created a new genetic resource of growing importance. Managers and researchers urgently need more effective data handling systems for storage, retrieval, and sequence comparisons; some may be by-products of the considerable investment in sequencing the human genome. But with these increase capabilities and resources will come an even greater need for well documented and managed germplasm collections.
As biotechnology becomes more affordable, it could improve access to collections by providing tools for characteristics their accessions. Information on the genetic similarity between accessions could aid in developing priorities for acquisition. Molecular techniques for characterizing genetic material, such as restriction fragment length polymorphism analysis, appear likely to provide the breeder with greater efficiency in selecting and developing new breeding lines and varieties. As a result, breeders may become more willing to use germplasm resources and hence to make greater demands on germplasm resource systems.
Policy and Politics
Awareness is growing among scientists, policymakers, and international organizations that germplasm is an important natural resource. In an international environment with conflicting economic systems and a skewed distribution of wealth and control over agricultural production and markets, the problems of germplasm conservation and management extend beyond purely technical issues. Plant and animal breeders, molecular biologists, and microbiologists must consider the broader social and economic ramifications of their work. If they fail to do so and isolate themselves in their laboratories in pursuit of research, the future of germplasm exchange will be determined by politicians, lawyers, and economists.
Quarantine should not be used to promote economic or political objectives.
The legal foundation that supports national quarantine regulations and actions is usually either legislation passed by national governments as acts, statutes, orders, decrees, or directives or enabling legislation that authorize a minister or secretary of agriculture to issue regulations. Some countries are also bound by quarantine regulations. Some countries are also bound by quarantine regulations that are promulgated by regional parliaments, such as the
European Community or Andean Pact. Most international plant quarantine activities take place under the legal umbrella of the International Plant Protection Convention of 1951.
Quarantine policies and practices should be biologically based and in accordance with known or potential risk that a hazardous pest or pathogen will gain entry through imported germplasm. Quarantine is essential for protecting a nation's agricultural system. However, regulations and practices must continually balance the potential for release of harmful pests or pathogens with the needs of germplasm scientists, research efforts, and breeding programs.
Intellectual properly protection systems should be designed to minimize the potential for restricting the free exchange of germplasm among nations.
Plant variety protection continues to be a controversial issue in the debates surrounding the free international flow of germplasm. Other forms of propriety rights are likely to become equally controversial as plants and animals as well as individual genes are given protection under the regular patent system. International political concern has been expressed over the growth of proprietary rights in the biological area, and particularly over the possibility that such rights benefit the developed world at the expense of the developing world.
In both the public and the private sectors, the increased value of germplasm (a value derived from commercial opportunities created through biotechnology) is leading to hesitation in sharing the material. The patent system plays a mixed role in this hesitation. In general, although the patent system appears to assist in increasing the rate at which technology advances, it sometimes makes it more difficult to use or commercialize any specific technological item (including new plant varieties), especially those developed privately.
Germplasm material held in collections, especially that originating in other nations, must continue to be broadly available. Intellectual property rights must allow protected materials to be used for research and breeding purposes.
Public institutions should not respond to the commercialization of germplasm by enacting restrictions that could limit the use of genetic resources by developing nations.
For many plant species, advanced traditional breeding is conducted primarily in the public sector, for example, in land-grant universities in the United States, in the more advanced research universities and publicly funded research centers in developed nations, and in a variety of international research institutions, such as those operated
by CGIAR. Although these institutions sometimes obtain legal protection for their working materials and research products, they have made such materials and products freely available throughout the world. However, the public sector has more recently used confidentiality or patents to support research or as a defensive step to prevent ideas or material from being patented or misappropriated by others. Public institutions should provide royalty-free licenses for the benefit of developing nations. In this way, they could use the patent system to assure continued broad availability of germplasm resources.
Disagreements over the ownership, control, and use of genetic resources must be resolved.
Although political will and cooperative relations among scientists are important to germplasm exchange, funding and technical resources for collection and management are major influences on distribution. Barriers to free exchange remain because of the lack of funding and staff to maintain and distribute materials on request. Governments and institutions that host international collections must be committed to maintaining and distributing them.
Government officials, agricultural scientists, and germplasm conservation personnel in developed and developing countries must recognize the necessity of cooperation in genetic resources conservation, exchange, and use. Cooperation is needed between the developing countries, which serve as centers of diversity, locations for rejuvenation of seed, and sites for in situ conservation, and the developed countries, which serve as sources of funding, preservation and distribution sites, and training centers. International cooperation and exchange of germplasm can be substantially strengthened by agencies, such as FAO, IBPGR, and the international agricultural research centers. Cooperation cannot be secured by statutory means alone, however. It must begin with scientist, environmentalists, and other interested parties who share a common concern for the world's genetic resources.
As the debates on freedom of access, ownership, and international accountability continue, genetic erosion also continues. In the meantime a practical and effective worldwide system of genetic conservation must be established. This will depend on strong national participation, particularly in the developing world, and the provision of stable, long-term, financial support.
The capacities for plant breeding, seed production, and biotechnology in developing countries should be strengthened. Plant breeding programs should have regional or international sources of reliable financial and technical support. Innovative methods of improving seed production and distribution in developing countries should be encouraged.
The governments of developing nations could strengthen biotechnology sectors by establishing appropriate economic incentives, regulatory requirements, and institutions. Public sector and extension activities should be structured to ensure that subsistence farmers participate in the benefits provided by these technologies. Accomplishing these goals will require bilateral and multilateral assistance in the form of training, facilities, and operating support.
Until recently, it has been relatively easy politically to conduct a large-scale international public sector agricultural technology development program. That type of program, which was responsible for the so-called green revolution, was often quite successful. Today, multilateral programs are often the objects of political criticism. Agricultural technology is also increasingly being developed in the private sector rather than in the public sector. These transitions underlie the germplasm controversy; they reflect the difficulty of ensuring that private-sector agricultural biotechnology, including breeding and seed production, provides expanded opportunities for developing countries.
International responsibility for conserving, managing, and using genetic resources must be translated into a form of funding that satisfies the basic principles of the International Undertaking on Plant Genetic Resources of the Food and Agriculture Organization.
Any strategy should build on existing framework and activities, stressing national involvement and the cooperation of FAO, IBPGR, and other CGIAR centers. A major criticism of the CGIAR has been that it has no formal legal basis for action among governments. Nevertheless, several of the CGIAR institutions have been leaders in conserving plant genetic resources. The overall CGIAR program in genetic resources might therefore be modified to include some form of governance as suggested by the FAO Commission on Genetic Resources. This might be done, for example, by an agreement between the CGIAR or its individual institutions and the FAO that obligates the institutions to consult with the FAO with respect to important policy issues.
It is also important to maintain existing policies with respect to free exchange of existing germplasm collections at the national and international level; the Convention on Biodiversity leaves this material
subject to free access. The convention will allow nations to place restrictions on the flow of later-collected germplasm. It will also be important to develop reasonable policies for respecting such restrictions.
Although the debate on legal and effective ownership continues, genetic erosion also continues, notably in developing countries (and in some germplasm banks), where most of the world's untapped genetic resources exist. It is in the interest of world agriculture that countries in regions with major genetic diversity be provided with the means to participate more fully in genetic resources conservation and use of the world's biological resources.
Genetic erosion is also prevalent in many germplasm banks. Sustained support of the banks and vigilance over their management are crucial to the security of germplasm collections.
An adequate and appropriate funding mechanism must be established to support national and international conservation, management, and use of genetic resources
The world scientific and technical community has put in place the beginning of a functional network of both national and international genetic resources programs that have the potential to safeguard germplasm. Present knowledge and rapid developments in several fields related to genetic conservation, including modern biotechnologies, provide a good basis for rational and selective conservation. Adequate operational funding is a key constraint.
Much has been achieved in collection efforts, training, the establishment of germplasm banks, documentation, and research support. However, the funding available for genetic resources activities at national and international levels does not reflect the substantially increased public and political awareness of the importance of genetic resources. The CGIAR has been a major provider of funds since the early 1970's. Fund from most other international sources have been smaller and, the debates of recent years notwithstanding, have not provided the substantial support that is needed. The Rio negotiations have provided a disappointingly small additional contribution to developing-nation environmental funding, including genetic resources funding, but they have affirmed the possibility of using the Global Environmental Facility, sponsored by the United Nations Environment Program, United Nations Development Program, and World Bank. Should that approach not yield an adequate and sustainable long-term funding base, stronger approaches should be sought, such as national contributions tied to domestic seed sales or a tax on worldwide seed sales.
Multilevel Collaborations on Genetic Conservation
All nations and international agencies need to pool their limited resources and collaborate on the myriad facets of genetic conservation. Worldwide concern demands that periodic assessment and monitoring of collaborative activities be required in the future to ensure maintenance and use of genetic resources, our common biological heritage.