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Managing Crop Genetic Resources

Plant germplasm activities in the United States have evolved since the colonists first brought seeds from their home countries and exchanged them with native Americans. Introductions of new crops and crop varieties to the United States were vigorously pursued from the late nineteenth century through the first decades of the twentieth century. Over the years, the reasons for assembling collections of crop germplasm have become more compelling. They now include concern over loss of biological diversity as well as the economic importance of accessibility to the germplasm resources needed to sustain national food supplies.

Germplasm resources are a strategic resource essential to national and global agricultural security. Recent technological advances such as cell and tissue culture, cryopreservation, and recombinant DNA (deoxyribonucleic acid) technologies provide the potential for innovations in preserving and using plant germplasm. As new technologies are developed it will be important for the United States to adopt those that can enhance its genetic resource conservation capabilities. The United States must also adopt policies and procedures to assure adequate preservation of resources, commensurate with its expanding activities and international responsibilities.

GERMPLASM AND GERMPLASM COLLECTIONS

Germplasm is the term used to describe the seeds, plants, or plant parts useful in crop breeding, research, and conservation efforts. Plants,



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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System 1 Managing Crop Genetic Resources Plant germplasm activities in the United States have evolved since the colonists first brought seeds from their home countries and exchanged them with native Americans. Introductions of new crops and crop varieties to the United States were vigorously pursued from the late nineteenth century through the first decades of the twentieth century. Over the years, the reasons for assembling collections of crop germplasm have become more compelling. They now include concern over loss of biological diversity as well as the economic importance of accessibility to the germplasm resources needed to sustain national food supplies. Germplasm resources are a strategic resource essential to national and global agricultural security. Recent technological advances such as cell and tissue culture, cryopreservation, and recombinant DNA (deoxyribonucleic acid) technologies provide the potential for innovations in preserving and using plant germplasm. As new technologies are developed it will be important for the United States to adopt those that can enhance its genetic resource conservation capabilities. The United States must also adopt policies and procedures to assure adequate preservation of resources, commensurate with its expanding activities and international responsibilities. GERMPLASM AND GERMPLASM COLLECTIONS Germplasm is the term used to describe the seeds, plants, or plant parts useful in crop breeding, research, and conservation efforts. Plants,

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System seed, or cultures are germplasm when maintained for the purposes of studying, managing, or using the genetic information they possess. Thus, seed of an old, heirloom tomato variety is just seed when produced by a gardener or seed company, but it is germplasm when part of a collection gathered to conserve the genetic diversity of tomatoes or to develop a breeding program for new tomato varieties, or even for the purpose of preserving particular genetically controlled traits. Today's scientists and crop breeders must have access to, and knowledge of, a wide array of crop varieties, landraces, and related wild species in their search for specific genetic traits. The seeds, pollen, or other plant materials in which these traits are found are called genetic resources, or germplasm. In the United States such materials are held in a cooperative network of federal and state facilities known as the National Plant Germplasm System (NPGS), the subject of this report. A collection of germplasm usually includes primitive landraces and wild species related to particular crops, and developed varieties and breeders' lines. Germplasm is used to develop new plant varieties for food, feed, fiber, turf, forages, and ornamentals and for forestry, industrial, and medicinal purposes. Hence, germplasm—the seeds and plants used as building blocks in breeding new cultivars—may be similar to the plants grown by a farmer or gardener, or they may be quite different and even further removed from the produce purchased in a market. Some germplasm needs little or no breeding to be useful. Many commonly used ornamental, medicinal, and herbal plants have been changed little from their wild progenitors. Plants, such as the popular ornamental, Bradford pear, were originally brought to the United States as germplasm (Creech and Reitz, 1971). By contrast, some germplasm accessions may be of value only for the individual genetic traits they possess. Residents of New England and the Northern Plains who grow yellow roses, particularly varieties that bloom early, can do so because the plants contain genes for hardiness from the Rosa xanthina, which was introduced early in the twentieth century by the famous plant explorer Frank N. Meyer (Cunningham, 1984). Germplasm collections include many kinds of materials used in crop breeding and development (Brown, 1989a,b; Chang, 1985; Creech and Reitz, 1971; Ford-Lloyd and Jackson, 1986; National Research Council, 1972; Plucknett et al., 1987). A large portion of the germplasm of many crops includes current and obsolete varieties. Breeders' collections may consist of inbred lines extracted from hybrids or varieties, superior varieties, elite lines with special combinations of traits, and intermated populations of elite and selected material. These sources of germplasm

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System are reasonably productive and are used most frequently by plant breeders. Other common sources are lines or varieties from elsewhere that may be unadapted to local growing conditions, markets, or industrial processes, but which may possess valuable characters. Obsolete varieties are also found in the collections of individuals and organizations that preserve the seeds of “heirloom” varieties. Primitive landraces, indigenous varieties, and specifically adapted ecotypes are important genetic resources. Genetically heterogeneous, adapted to specific local environments, and often unsuitable in appearance or quality for modern markets, they can be rich sources of genes. The races of maize developed by the American Indian and the landraces of cereals, forages, vegetables, and ornamentals brought by immigrants formed the germplasm base from which U.S. agriculture developed. Landraces are the products of centuries of planting, selecting, and replanting by farmers. The areas of the world where they were developed contain considerable genetic diversity and are important collecting sites for germplasm. Researchers have developed collections of genetic stocks for several The Andean highlands, farmed for more than 2,000 years, are important sources of genetic diversity for the potato. Traditional landraces, still cultivated by present-day farmers, and naturally occurring Solanum species are found there. Credit: Calvin Sperling.

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System crop species. These accessions have unique mutant genes, groups of genes, or gene deletions or duplications; interchanged or translocated chromosomes, where two distinct chromosomes had broken and the parts of each were then interchanged; and chromosomes with portions that are inverted. Some of the stocks may have duplicate or deleted chromosomes or may represent genetically distinct cytoplasms. Although not used by consumers, genetic stocks are essential to genetic and cytogenetic research and some plant breeding procedures. These include, for example, locating nonnuclear genes in chloroplasts or mitochondria and studying photosynthesis and cytoplasmic male sterility. For some crop species, many genes have been “mapped” according to their linear arrangement on a chromosome. These maps are extremely valuable for gene manipulation and basic research. Genetic stock collections are often difficult and expensive to maintain, and specialized knowledge, skills, and facilities are required to increase and maintain accessions. Special germplasm collections accumulated through genetic and breeding research have been the basis for studies of speciation, evolution, or taxonomy; manipulations of genes, chromosomes, or entire genomes; and the incorporation of genes into crop plants from weedy relatives or related species. Some important special collections have become part of the NPGS. Many, assembled by researchers at state or privately supported universities and used by those researchers throughout their careers, are extremely vulnerable to loss and may be abandoned or discarded by later researchers with other interests. PRESERVING PLANT GERMPLASM Seeds are the most commonly preserved form of germplasm. Those of the major cereal grains, legumes, and most vegetable crops can be dried and stored for long periods under low humidity and at low or subfreezing temperatures. After storage, such seeds germinate readily, although some may require specific conditions of temperature, moisture, light, or darkness. Sometimes, to overcome seed dormancy, environmental conditions such as light, temperature, and humidity must be manipulated. Even then, a few species or accessions may germinate poorly or slowly. For several reasons germplasm of some crops may not be stored as seed. In these cases germplasm must be maintained as live plants in the field or under cover (e.g., greenhouse or screenhouse), pollen, tissue cultures, or cuttings (e.g., scion wood of fruit and nut trees). Many important tropical crops, such as cocoa or Hevea rubber, and some temperate species, such as wild rice (Zizania aquatica), have seeds

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System that are damaged when dried and cooled. These seeds have often been termed recalcitrant, but are more correctly described as desiccation sensitive. These species must be maintained as living plants in field plantings or in a greenhouse. Plants can be raised from seed or when a particular clonal genotype from vegetative propagules (e.g., cuttings, bud grafts) is required (e.g., for many tree fruits and nuts or sugarcane). Clonal maintenance is also necessary for crops that lack true seed or have seed that is rare or difficult to obtain (e.g., banana and garlic). The emerging techniques of biotechnology have opened new opportunities for germplasm storage and use (Peacock, 1989). Tissue culture is increasingly used to preserve virus-free plants and to supplement field plantings of germplasm when seed storage is impractical. Embryos may be excised from developing seeds and grown on artificial media when, for various reasons, they would not be viable if left to mature. Cryopreservation—storage in or suspended above liquid nitrogen at temperatures from −150°C to −196°C—may greatly extend storage periods. Finally, it may be possible one day to maintain isolated DNA routinely and to use it for crop improvement. DNA contains the molecular sequences that comprise genes. Thus, an organism's isolated DNA contains all of its genes. The potential to store isolated DNA underscores the central importance of germplasm as genetic information. This technology is already becoming available. However, its general application to germplasm management and crop improvement will require considerably greater knowledge of gene structure, regulation, placement, and function than currently exists as well as more precise understanding of the genetic control process of important crop traits. Larger human populations, widespread use of new high-yielding varieties, and agricultural development projects focus concern on the collection, maintenance, and evaluation of genetic resources that are disappearing from farmers' fields and their native environments. Society's increased awareness of its obligation to prevent loss of the world's biological diversity has served to broaden the scope of germplasm conservation to include a wider range of species. Ultimately, the size and scope of germplasm activities in the United States must enlarge and additional efforts will be needed to accommodate this expansion. THE CHALLENGES OF CONSERVING AND MANAGING PLANT GERMPLASM The first challenge to a plant germplasm program is to acquire representative sets of samples of those species that merit conservation. Obtaining a genetically diverse collection usually means adequate

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System sampling from the distribution range of the selected species. Crops already are represented by a broad range of diversity and samples may be obtained from the institutions holding them. For many species, however, collections are incomplete and require further exploration and expansion. Since germplasm collections are established for long-term (in perpetuity) conservation, they should reflect deliberate decisions concerning the materials critical to the welfare of a nation's agriculture and environment, and the provision of long-term technical support and funding for maintenance. A well-defined and accepted policy should WILD RICE Zizania aquatica L. GRIN Data No wild rice accessions are listed in the GRIN. Wild rice can be found growing naturally in Minnesota. Credit: Calvin Sperling. Wild rice (Zizania aquatica) was a staple of American Indian life for hundreds of years, but it has been barely 20 years since the first successful commercial efforts were made to grow this reed-like aquatic grass in the United States. Native to the central and upper Great Lakes region and to New England, wild rice anchors itself with shallow roots in mud with its stalks extending upward through as much as 6 feet (2 meters) of water. Seventeenth century French explorers described the plant as folle avoine, wild oats, to which it bears closer resemblance than to cultivated rice. It was not until the early twentieth century that wild rice appeared in markets. Favored for its taste and keeping qualities, wild rice was being served in restaurants in Minnesota's hotels. The concept of cultivating Z. aquatica seemed out of the question, so wild rice was collected for these markets from wild plants. The primary problem was that the seeds of the plant shattered, or fell off, upon ripening. The absence of shattering allows grains such as oats, wheat, and barley to be successful commercial crops. Early pioneering efforts to cultivate wild rice met with losses as high as 90 percent.

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System state the focus of the collections as well as their extent, goals, and mode of operation. Managing a germplasm collection extends far beyond acquiring the plants or seeds that comprise it and holding them under conditions of long-term storage. The prime reason for assembling collections is to make them available for breeding and research. They are also insurance against loss of rare and endangered wild species that are conserved in situ. Regeneration, characterization, evaluation, and documentation are important parts of the activity of managing genetic resources that must be addressed by a program. The breakthrough that allowed farmers to grow wild rice came somewhat unexpectedly from a routine inspection of a field in Waskish, Minnesota, in 1963. Dr. Paul Yagyu and graduate student Erwin Brooks noted that unlike most other plants in the field a few apparent mutants seemed to retain their male flowers long after shedding their pollen. While such a characteristic would not necessarily imply that the same plants would hold mature seed, the two scientists speculated that this might be the case. In fact, offspring of those plants did shatter less and led to development of shatter-resistant wild rice. Their genes are now in all kinds of commercial wild rice. Today Minnesota and California grow wild rice commercially with about 26,000 acres under cultivation. The 7.6 million pounds of wild rice produced in 1988 was worth about $15 million. Canada, the only other country to produce wild rice commercially, accounted for about 2 million pounds in 1987. Wild rice has a long way to go before it can be considered truly domesticated. Although current crops are less shatter prone than most wild types, about half of the seed still falls before it can be collected. Additionally, plants are tall and produce a large amount of straw in relation to grain. Wild rice is vulnerable to brown spot, a serious fungal disease that is severe in the standing water culture system used for wild rice. Like other crop improvement programs, researchers are seeking to locate additional wild rice plants and to discover useful traits that can be transferred to domesticated lines. It may be that there are additional traits hidden in wild Z. aquatica plants that will further improve this newly domesticated grain. But that effort is in its infancy, and there is no central facility that conserves wild rice seed for future breeding programs, in part because the seeds themselves must be stored at high-moisture content and have relatively short periods of viability. The narrative was prepared from information supplied by Noel Vietmeyer, National Research Council. GRIN = Germplasm Resources Information Network.

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System Seeds do not live indefinitely. Regeneration or replenishment can be an expensive, labor-intensive, time-consuming, and important process that is all too often unappreciated. A range of sites and seasons with appropriate temperature, moisture, day-length, length of frost-free growing season, and appropriate cultural conditions must be available. Populations of plants large enough to minimize the loss of alleles and shifts of gene frequencies must be established. Few plants are needed for individual homozygous accessions of self-pollinating species, but several hundred may be necessary for maintaining variable populations of self- and cross-pollinating accessions to retain genetic diversity. Seeds of high quality can be stored for many years (e.g., 50 or more for most accessions of cereal crops or beans), reducing the frequency of regeneration and its accompanying risk of error, genetic drift, or destruction by pests, diseases, or natural calamities. Among the most important information on each accession is the ecogeographical information and the specific plant and ecological data obtained at the time of collection. This is referred to as passport data. Each time a sample is grown for regeneration there is opportunity to collect data on plant height, flowering date, lodging, vigor and senescence, fruit color and size, relative yield, and other characters. Detailed information should be available for at least a representative set (sometimes called a core) of accessions of a species or crop. This will usually involve special screening tests designed to measure disease and insect resistance, tolerance to various field environments, replicated yield trials, or even yield evaluations of many stocks hybridized by an elite, adapted tester as the common other parent. Germplasm that must be maintained as field or greenhouse collections can be lost in several ways. Pests and diseases can devastate germplasm when it is grown to replenish seed, or when maintained in field collections. Wind, hail, frost, and drought can affect the survival of field collections. The landrace collection of potatoes held by the Centro Internacional de la Papa (International Potato Center) in Lima, Peru, for example, has been damaged by weather in the past and would have been partially lost were it not for duplicates maintained at another site. The proximity of eastern filbert blight to the National Clonal Germplasm Repository in Corvallis, Oregon, may necessitate moving the collection to another more remote back-up site. STRUCTURE OF A GERMPLASM MANAGEMENT PROGRAM The basic elements of germplasm management are shown in Figure 1-1. These are grouped into acquisition, conservation, management, and utilization. Acquisition includes developing priorities for adding to

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System FIGURE 1-1 The basic elements and flow of materials within a germplasm management program. the collections, exploring, and collecting. It also involves exchange with other collections or donations from various sources. Knowledge of existing collections and information about the genetic diversity of the crops in general help in setting exploration priorities. The aim of acquisition is to obtain the most genetically diverse collection possible of the crop and its useful relatives (Simmonds, 1979). Accessions that can be stored as seed are conserved and maintained in active collections from which distribution to breeders and other users can be made. These must be backed up by secure base collections, held in long-term storage (for most seed this is at −18°C or below, and 5 to 7 percent seed moisture). Clonal germplasm and materials not easily

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System The U.S. collection of wheat germplasm is held in cold storage at the National Small Grains Collection in Aberdeen, Idaho. Credit: U.S. Department of Agriculture, Agricultural Research Service. stored as seed are maintained in active field collections or in screenhouses or greenhouses. Tissue culture, in vitro storage, cryopreservation, and pollen storage provide alternatives for medium-term and long-term maintenance. Special sites or facilities are used for these purposes. Management involves more than the storage or housing of stocks. Small seed lots may need to be multiplied to increase the sample size or to improve viability before they become part of a collection. Seed must be increased or regenerated when the viability of the stored sample declines or the sample becomes too small because of testing or distribution. Seed samples must be tested regularly to detect decline in seed viability. Collections must be characterized, evaluated, and documented to aid in selecting materials for breeding or research. Evaluations for particular traits of interest are performed either by users or by germplasm curators in response to immediate or anticipated needs. Core collections that represent the genetic diversity of the whole collection can aid researchers in identifying the potentially useful accessions in large collections of a single crop (Brown, 1989a,b). Documentation is the responsibility of curators. The utilization of germplasm collections, until recently, was generally

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System considered to be for the use of plant breeders and research scientists. However, collections, as reservoirs of biological diversity, including rare or endangered species, can aid in conservation and management efforts (Brown et al., 1989; Office of Technology Assessment, 1987). Ironically, breeders do not frequently seek new materials from germplasm collections (Duvick, 1984). In part this is because of the long time it may take to screen for desired traits and breed them into appropriate genetic backgrounds. Breeders depend heavily on data from evaluation trials to select materials for their breeding programs. Duvick found that breeders prefer to use the adapted materials produced by other breeders. Infrequent use also can result from inadequate information being obtained or disseminated about accessions. There are also cases where elite foreign germplasm is unavailable through the NPGS and the breeder must seek acquisition independently. The Diversity and Size of Collections During the past 20 years, the maintenance of biological diversity has become an important part of national and international development activities. The realization that many species and primitive landraces face extinction has accelerated concern about and increased the potential size and scope of collections. An emphasis that includes a wider range of wild species related to crops may also increase the size of collections. Further, new technologies for gene transfer hold the promise that plant breeders may be able to move genes freely among distantly related species. The usefulness of collections thus would not be limited to the diversity within a species. The degree to which a collection represents the genetic diversity available in the species is more important than its size. Nevertheless, capturing a wide range of diversity can require a relatively large number of accessions. Suggestions for ways of managing large, diverse germplasm collections to facilitate their efficient use despite their size have been proposed (Brown, 1989a; Chang, 1989). In the future, such practices as identifying a core or representative subset of NPGS collections could become increasingly important, especially to evaluate specific traits. Management and Global Responsibility No single national plant germplasm system can assure the protection and conservation of all plant diversity or even all of the diversity among known economically important plants. Protection and conservation require the participation of many nations. A global strategy may eventually emerge from current discussions about conserving biological

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System diversity. A global plan would consist of a mosaic of national and international collaborative efforts that together would assure effective conservation of biological diversity. In the interim, nations must do what they can to meet their respective needs. In the United States, germplasm efforts must be organized as part of the emerging global system. Priorities and goals should reflect the responsibilities of participating in an international cooperative effort to manage plant genetic resources. The U.S. plant germplasm collection, one of the world's largest and most diverse, shares responsibility for preserving many unique landraces no longer obtainable in their countries of origin because of habitat loss and genetic erosion. PLANT GENETIC RESOURCES IN THE UNITED STATES Most of the rich and varied plants of U.S. agriculture come from many regions of the world. Modern crops, each representing a broad array of genetic materials, reflect the transition from their wild origins through the process of domestication, farmer selection, and more recently intensive breeding. When the European colonists first arrived in the New World they WILD OAT PI 317757 Avena sterilis L. GRIN Data Cultivar: 6-1272-131 Origin: Israel Maintenance site: National Small Grains Collection Year PI assigned: 1966 An Iowa State University graduate student research project in the late 1970s used a wild-oat species that led to one of the most productive oat cultivars yet introduced in the United States. Plants of PI 317757, a wild species of oat collected from Israel over a decade earlier in the mid-1960s, were found to produce higher than average amounts of grain. However, like most wild grains, the seeds fell off the stalks (shattered) upon ripening, before they could be harvested. The challenge was to transfer the high-yield factor to a cultivated variety while leaving the shattering tendency behind. Complicating this was the fact that some of the genetic traits desired from the wild plant were not found in the chromosomes of the nucleus, but were carried in smaller molecules of cytoplasmic DNA. Genes of this nature are inherited only

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System found an agriculture based on fruits, nuts, berries, beans, herbs, squashes, tobacco, and corn—all species unknown to them. The hard flint corns of the New England Indians contributed greatly to the development of modern maize varieties used around the world (Cox et al., 1988; Wilkes, 1988). Early settlers also brought many crops from their homelands to North America. The introduction of new crops and crop varieties from other countries has continued in the United States since the early colonial days. This influx of plants, combined with distinct climates and soil types, has led to the development of a diverse agriculture. The gathering of plants from around the world was formalized near the end of the nineteenth century, and conserving and safeguarding them became a major concern in the 1940s (Purdue and Christenson, 1989; White et al., 1989). The Foundation of Crop Improvement The growth in agricultural production in the United States has been remarkable. For example, yields of corn, wheat, and potato increased 333 percent, 136 percent, and nearly 300 percent, respectively, between 1930 and 1980 (Witt, 1985). In the economic arena, agricultural exports ,from the female half of a cross. A breeding program had to be developed with this constraint in mind. The resulting hybrids contained both nuclear and cytoplasmic genes from the wild-oat species. one, named Hamilton, proved more productive than the rest. It produced By 1983, 20 separate lines had resulted from the breeding work and yields of 85 bushels per acre compared with about 70 bushels per acre for other varieties. But more significant, Hamilton is the first oat variety to possess cytoplasmic genes from a wild species. It is the interaction of these genes with those in the nucleus that have been found to enable Hamilton not only to produce well, but also to resist disease. The Hamilton cultivar was, for example, found to be resistant to barley yellow dwarf virus, a common disease of oats. It also has broad adaptability to different environments and is less susceptible to lodging, a condition in which the plant topples over from its own weight. Other genes from PI 317757 have been used to raise the content of oil in oat seed. Such improvements may one day enable oats to become a profitable oil-seed crop, which would be especially useful at more northern latitudes where a limited number of crops can be grown as oil sources. “GRIN Data” for the plant introduction (PI) number above represent information contained in the Germplasm Resources Information Network (GRIN). The narrative was prepared from information supplied by Kenneth J. Frey, Department of Agronomy, Iowa State University.

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System The viability of U.S. agricultural production depends on developing new and improved crop varieties. Credit: Pioneer Hi-Bred International, Inc. accounted for $28 billion, or 12 percent of total domestic exports, in 1987 (U.S. Department of Agriculture, 1989a). Crops and food products accounted for 81 percent of these exports. Cash receipts from the sale of crops in the United States totaled $72.6 billion in 1988, an increase of 17 percent from the previous year (U.S. Department of Agriculture, 1989b). Plants also have significant economic value to pharmaceutical, cosmetic, and other industries. Germplasm forms the foundation on which modern plant improvement rests. The genetic basis of high productivity in modern wheat, resistant to pests, diseases, and other stresses, was assembled by combining landraces and breeding lines from around the world. Plants used in breeding modern crop varieties often include related wild species. Most of the genes for pest and disease resistance in tomatoes come from wild Lycopersicon species. Promising experimental improvements in cotton fiber quality have come from apparently worthless wild Gossypium species having little or no fiber. Landraces grown from seed passed by farmers from one generation to the next, although adapted for survival in a particular region, may contain genes that enable them

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System to resist environmental stresses, such as drought tolerance or disease resistance, in other regions. Much of the corn in the Midwest is derived from two major races native to the Americas: the Northern Flints of the northern and eastern United States and southern Canada, and the Southern Dents derived from materials introduced from Mexico during the sixteenth century (Cox et al., 1988). By contrast, hard red winter wheat in the United States is largely derived from seeds brought by Mennonite immigrants in 1873 (Cox et al., 1988; Wilkes, 1988). Cultivated barley was introduced to the New World by early explorers, including Christopher Columbus (Cox et al., 1988). Soybean came from northern China, but an important introduction to the United States, designated PI 159925 (plant introduction number), arrived as part of an exchange of materials with Peru, where soybean is neither native nor a major crop. Improving crop varieties from diverse backgrounds is a continuous process. Modern agriculture requires a flow of enhanced crop varieties that are productive in spite of pests, diseases, or climatic extremes. Improvements or changes in flavor, nutritive value, and shipping endurance have been added. Not long ago consumers sought out Golden Bantam sweet corn for their summer meals. Today, newer, more palatable varieties with improved disease resistance have replaced this long-time favorite. The highly productive agriculture of the Green Revolution was based on fertilizer-responsive dwarf varieties of wheat and rice assembled from widely divergent genetic materials (Dalrymple, 1986a,b). Each year presents the farmer, the consumer, and even the backyard vegetable gardener with numerous new varieties that may taste differently, are more productive, or have better disease resistance than previously released varieties. Perhaps not surprisingly, grass-roots, nonprofit groups have arisen to recover and protect the older cultivars of garden vegetables for a variety of conservation, cultural, and aesthetic reasons (Office of Technology Assessment, 1985; Shell, 1990). Farm crops have always been vulnerable to environmental stresses, diseases, or pests, but farmers now grow crops that are more resistant to them. Diseases and pests change, however, and so must the varieties developed by plant breeders. New varieties must be developed to replace those endangered by shifts in pest and pathogen populations, or with outmoded performance or quality (see Figure 1-2) (National Research Council, 1972; Plucknett and Smith, 1982). Importance to Society and the Environment Genetic resources can be lost or diminished through habitat destruction, displacement by other species, natural disasters, and neglect. As

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System FIGURE 1-2 Commercial cultivars are often replaced with newly developed ones that have better production qualities, yields, or resistance to pests or pathogens, as illustrated in (A) winter wheat and (B) sugarcane. Sources: (A) Plucknett, D. L., N. J. H. Smith, J. T. Williams, and N. M. Anishetty. 1987. Gene Banks and the World's Food. Princeton, N.J.: Princeton University Press. (B) Plucknett, D. L., and N. J. H. Smith. 1986. Sustaining agricultural yields. BioScience 36(1):40–45. Reprinted with permission by (A) Princeton University Press, ©1987, and (B) American Institute of Biological Sciences, ©1986.

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System the basis for modern agriculture, they are strategic resources of concern to humanity. From these resources society derives food, shelter, clothing, pharmaceuticals, chemicals, and many other products. The conservation of the broad range of plant genetic diversity, even when narrowed to agricultural concerns, is beyond the capacity of individuals, private companies, or small groups, although each of these can and does contribute to managing genetic resources. It requires the cooperation of a broad range of scientists, policymakers, administrators, and other concerned individuals. The secure and strategic conservation of genetic resources is a national government responsibility. International Exchange The materials held in U.S. collections have provided important support to the agriculture of many nations. Some 110,000 accessions of the National Small Grains Collection are among the most frequently distributed genetic resources in the world. In response to requests from abroad, the United States dispatches more than 230,000 seed samples to over 100 countries each year. The United States also plays a significant role in safeguarding important global collections. U.S. collections have been used to restore lost or damaged germplasm collections of other nations. For decades, the United States has served as a third-party quarantine site and supplier for developing nations seeking the germplasm of coffee, cocoa, rubber, and other species. Duplicate samples of rice from the International Rice Research Institute and maize from the Centro Internacional de Mejoramiento de Maíz y Trigo (International Maize and Wheat Improvement Center) are held as partial back-up collections for those institutions, to insure against loss. In addition, the United States cooperates with the International Board for Plant Genetic Resources (IBPGR) and the United Nations' Food and Agriculture Organization (FAO) to conserve the world's crop genetic resources. The United States has accepted responsibility for 18 of its collections, including those of maize, millet, rice, sorghum, wheat, beans (Phaseolus spp.), and soybean, to serve as international base collections within IBPGR's network (Hanson et al., 1984; International Board for Plant Genetic Resources, 1989; National Research Council, 1988). ORIGINS OF THE NATIONAL SYSTEM The NPGS was established in 1974 as a collaboration of the federal government, states, and private industry to foster better management of the plant germplasm needed to sustain a productive agriculture.

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System Food in the United States is relatively inexpensive, abundant, varied, and safe, in part because of the success of modern plant breeding and agriculture. For example, new high-yielding, disease-resistant wheat varieties have ensured that flour has remained a relatively inexpensive, readily available commodity over many decades. The NPGS has been described as a “user-driven system” (Murphy, 1988:210). It must serve the changing needs of a varied clientele in medicine, fiber, food, forage, industry, research, and other fields. It must also provide information and materials accurately and efficiently from its collections to those users. Development of Germplasm Activities in the United States Efforts to gather genetic resources began in the early days of the Republic when various officials of the U.S. government asked citizens PEANUT PI 314817 Arachis hypogaea L. GRIN Data Cultivar: MANI Origin: Peru Acquisition: Peru Maintenance site: Southern Regional Plant Introduction Station Year PI assigned: 1966 The Institute of Plant Breeding in the Philippines maintains a sample of PI 314817. Credit: North Carolina State University, Peanut Breeding Laboratory. It was serendipity that the peanuts collected by Dr. David Timothy in a trip down Peru's Huallaga River in 1966 turned out to confer resistance to two important diseases of the peanut. Timothy, a forage grass breeder at North Carolina State University, was in Peru to collect specimens of Tripsacum, a wild species related to maize. A storekeeper in the small river town of Juanjui, Province of Mariscal Caceres, in the Amazon basin gave him seeds of a locally grown peanut. The seeds were from remote plantings in sand bars on the Huayabamba River, up river from the village of Pachiza and above its confluence with the Huallaga River. Because the plants had been cultivated repeatedly in that area for a long time, Timothy guessed that they might possess distinct genetic traits. They were intro

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System living or traveling abroad to send back seeds or plants of promising potential for new trees or crops (Hodge and Erlanson, 1956; Klose, 1950; White et al., 1989). John Quincy Adams, the sixth president, issued one such plea and similar requests came from Thomas Jefferson, Benjamin Franklin, and others. From 1836 to 1862, before the U.S. Department of Agriculture (USDA) was established, the U.S. Patent Commissioner's office sent seeds and plants of foreign origin to farmers throughout the United States. The idea was supported by several members of Congress through the use of their postal franking privileges. This activity ended in 1923 when seed distribution became the responsibility of the USDA. It had, by then, grown from a cost of $1,000 in 1839 to $360,000 in 1922 (just under 11 percent of the USDA budget at that time). In 1898, the Seed and Plant Introduction Section, which later became the Plant Introduction Office, was established to promote the exploration duced into the United States and given the designation PI 314817. It was subsequently discovered that these plants were resistant to two serious diseases, peanut rust and late leafspot. Peanut rust is especially devastating to crops in Central and South America, Africa, and Asia, where the crop is an important staple. Although not generally a problem in the United States, the disease can in some years cause crop losses of up to 70 percent in peanuts grown in southern Texas. Leafspot is more common in the United States and can reduce yields as much as 50 percent. The genes for resistance to these diseases have been successfully transferred from PI 314817 into a breeding line of peanuts known as Tifrust-14, that was released cooperatively by the U.S. Department of Agriculture's Agricultural Research Service, the University of Georgia, and the International Crops Research Institute for the Semi-Arid Tropics in India. This line has been distributed by the U.S. Department of State's Agency for International Development in Thailand and in the Philippines to promote development of advanced breeding lines with rust resistance and high yields. This has been a lengthy process, and only recently have rust and leafspot resistant peanut lines been released to farmers. Several south African nations, Thailand, and the Philippines are also planning to grow the resistant varieties. The delays result from the time it takes to breed and select the few desired genes—in this case for disease resistance— while discarding unacceptable traits, such as poor quality or low yield. This deliberate, sometimes tedious, process of enhancement is crucial to harvesting the benefits hidden in an accession of plant germplasm. “GRIN Data” for the plant introduction (PI) number above represent information contained in the Germplasm Resources Information Network (GRIN). The narrative was prepared from information supplied by Johnny C. Wynne, Department of Crop Science, North Carolina State University.

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System for and introduction of new crops. David Fairchild, Frank N. Meyer, and others introduced a broad range of new crops and genetic resources of existing crops (Cunningham, 1984; Hodge and Erlanson, 1956; Hyland, 1984; Klose, 1950; White et al., 1989). At the same time the plant introduction (PI) numbering system, still used by the NPGS, was established. The section's Foreign Plant Introduction Office emphasized collecting. In the early 1930s, for example, H. G. MacMillan and C. O. Erlanson collected wild and primitive potatoes in Peru and Chile to obtain plants with genes for insect and disease resistance. Other plant hunters were in the West Indies searching for Sea Island cottons. R. Kent Beattie was completing a 5-year mission in China to collect chestnuts to replace the blight-stricken American chestnut. C. Westover and W. E. Whitehouse were searching for alfalfa in Russia as sources of resistance to bacterial wilt. Whitehouse then went on to Persia to collect melon, peach, apple, and pistachio germplasm. At the same time, W. J. Morse was making his now-famous contributions of thousands of wild and cultivated soybeans from China, Korea, and Japan. The 1936 and 1937 editions of the USDA Yearbook of Agriculture recorded the genetic diversity of many crops of that time, but there were no nationally coordinated activities to preserve germplasm. In the 1940s the National Academy of Sciences' Committee on Plant and Animal Stocks expressed concern over the fate of the resources that formed the foundation for the world's crops. In a 1946 letter to Sir John Orr, the director general of the FAO, National Research Council Chairman Ross G. Harrison sought action by that organization and wrote the following (Harrison, 1946:1): As improved varieties are introduced to production, large numbers of older, more diverse stocks disappear. A permanent loss of characters necessary for further improvement thus is likely to occur. As a safeguard to the welfare of all peoples, steps should be taken as soon as possible to collect and maintain the plant and animal materials likely to be of service in breeding. In the summer of 1946 the 79th Congress passed Public Law 733; Title II of which is the Agricultural Marketing Act of 1946. This act provided the legal basis for establishing state-federal cooperation in managing crop and livestock genetic resources, and included an amendment to the earlier Bankhead-Jones Act of 1935 to support research (Title I). It also attempted to improve the marketing and distribution of agricultural products (Title II), and established a national advisory committee to the secretary of agriculture and the U.S. Department of Agriculture on matters of research and service authorized by the act (Title III).

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System The potato introduction project was begun in 1947 by breeders to maintain valuable South American and other potato germplasm; a site was established in Sturgeon Bay, Wisconsin, in 1950. The first of four regional plant introduction stations was established in Ames, Iowa, in 1948. Three more stations followed at Experiment, Georgia (now Griffin, Georgia); Pullman, Washington; and Geneva, New York. In 1958 the National Seed Storage Laboratory was opened at Ft. Collins, Colorado. Following congressional passage of the Agricultural Marketing Act of 1946, action was taken to establish a cooperative enterprise that was coordinated through the newly designated Plant Introduction Section of the Agricultural Research Service (ARS). This included participation by ARS, the state agricultural experiment stations, the Cooperative State Research Service, and where appropriate, the Forest Service, the Soil Conservation Service, and the Bureau of Land Management. This combined effort involved close collaboration between those responsible for the acquisition and conservation of germplasm and federal, state, and private users. It was organized with a national office responsible for collecting and introducing germplasm, as well as through a series of regional and interregional stations responsible for the increase, maintenance, evaluation, documentation, and distribution of germplasm. Technical and administrative committees from the federal and state systems coordinated these activities. Emergence of the NPGS The NPGS has been described as a diffuse network of federal, state, and private institutions, agencies, and research stations (Council for Agriculture and Technology, 1984; General Accounting Office, 1981a,b; National Research Council, 1972; Office of Technology Assessment, 1987). Some reports have criticized its apparent inability to manage well all of the germplasm held by its cooperators. However, the system is still relatively young and is evolving to meet the rapid changes in technology and in the economic, legal, and political requirements of U.S. and world agriculture. The present NPGS emerged 2 years after a 1972 restructuring of the ARS. The change underscored the recognition of the importance of genetic resources management and the need for a coordinated, national effort. The system has been an umbrella for an extensive array of germplasm management activities throughout the country. U.S. scientists, in assembling a wide range of crop germplasm, presaged the recognition by other nations of the threat of loss of genetic diversity in primitive cultivars and landraces. Many NPGS stocks no

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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System longer exist where they were originally collected. Many early breeders ' lines would also have been lost unless conserved in collections, such as those of the NPGS. The NPGS is the world's largest distributor of plant germplasm. Accessions from its collections can be found in important crop collections throughout the world. Both public and private institutions have received plant materials, usually small amounts of seed, from the NPGS to support breeding and research programs. The NPGS does not supply seed for direct commercial use or agricultural production. U.S. germplasm activities to a large degree have been based on an unofficial policy of ensuring national self-sufficiency. However, today the United States plays a more global role by providing support and leadership in planning and implementing international as well as U.S. programs. Earlier commentaries on the NPGS have highlighted its shortcomings and needs as well as its successes (Council for Agricultural Science and Technology, 1984; General Accounting Office, 1981a,b; Office of Technology Assessment, 1987; U.S. Department of Agriculture, 1981). Increased appropriations, reapportionment of existing resources, construction of new facilities, and some centralization of responsibilities have been recommended to meet some of its more urgent needs (Office of Technology Assessment, 1987). Significant efforts have been made in recent years to address some of the concerns outlined in these reports and to improve the maintenance of germplasm held by the NPGS, but some issues persist. This report does not review the findings of earlier reports, but analyzes and offers recommendations for future directions and activities of the NPGS. It proposes administrative, operational, and structural actions that could strengthen the NPGS and ensure a scientifically sound, responsive, and efficient system well into the twenty-first century. Toward this end, the components of the national system are described in the next chapter.