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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System 2 Elements of the National Plant Germplasm System T he size and organization of a program to manage genetic resources varies with the goals and policies of a nation and the resources it is willing to commit to that purpose. There are, however, basic elements essential to all national programs for managing plant genetic resources. This chapter describes the components of the National Plant Germplasm System (NPGS) in the context of the elements of the model outlined in the preceding chapter (Figure 1-1). GENETIC RESOURCES IN THE UNITED STATES The basic mission of the national system is to make available plant germplasm to scientists in the United States and worldwide for plant improvement, research, teaching, or extension programs. Activities include exploration, exchange, collection, and introduction; increase or regeneration; evaluation; documentation; preservation or maintenance; and distribution. Prior to reorganization of the Agricultural Research Service (ARS) in 1972, the major components of the germplasm system were administered through the ARS New Crops Research Branch within the U.S. Department of Agriculture (USDA), or, for some major collections, through the specific USDA-ARS branch dealing with that commodity. In 1974, following the reorganization, germplasm activities were grouped into the National Plant Germplasm System to provide an umbrella system for germplasm acquisition, preservation, preliminary evaluation, and distribution. With the ARS holding lead administrative responsibility,
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System the system was designed “to provide, on a continuing basis, the plant genetic diversity needed by farmers and public and private plant scientists to improve productivity of crops and minimize the vulnerability of those crops to biological and environmental stresses” (Jones and Gillette, 1982:1). The NPGS is composed of several stations, repositories, or laboratories with varying responsibilities and locations throughout the United States (Table 2-1). The system holds more than 380,000 germplasm accessions representing more than 8,700 species. While most of the activities of the U.S. germplasm program take place within the NPGS, no single site is solely responsible for all of them. The National Seed Storage Laboratory (NSSL), for example, is a specialized facility for long-term preservation that serves as a security backup to the active collections around the country. Seed viability testing and long-term storage are the major functions of the NSSL. Regeneration, characterization, evaluation, and distribution are performed elsewhere. While routine requests for seeds are often received at the NSSL, they are generally forwarded to and filled by a curator responsible for the particular active collection. Cooperation and coordination among the components of the national system are essential. Individual sites may not be suitable for managing all of the accessions for which they have primary responsibility, and some accessions must be grown or regenerated at another site. Thus a station may maintain several species for which it has primary responsibility and may also grow plants for other collections. Materials that require short day-lengths to flower are problematic because the locations or other resources needed for regeneration are not always readily available. Although spread over numerous locations, the NPGS is intended to function as an integrated national system for germplasm management. Plant materials entering or distributed from the NPGS follow predictable lines (Figure 2-1) of acquisition, conservation, management, and utilization. These activities are described below. ACQUISITION The Plant Introduction Office (PIO) and its predecessors have been responsible for the acquisition of germplasm since 1898. Closely allied to this office are plant exploration activities and the health and quarantine of imported plant materials. Accession documentation begins when the PIO records passport data that accompanies new accessions for entry into the Germplasm Resources Information Network (GRIN) database. All of these activities are conducted through the National Germplasm
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System TABLE 2-1 Crop-Related Responsibilities in the National Plant Germplasm System Facility and Location Primary Crops or Species Conserved Regional plant introduction station Western, Pullman, Washington Common bean, garlic, Allium (onion) species, lupine, safflower, chickpea, wild rye, lettuce, lentil, alfalfa, forage grasses, horsebean, common vetch, milkvetch Southern, Griffin, Georgia Sweet potato, sorghum, peanut, pigeon pea, forage grasses, forage legumes, cowpea, mung bean, peppers, okra, melons, sesame, eggplant Northeast, Geneva, New York Tomato, birdsfoot trefoil, pea, clover, brassicas, onion North-Central, Ames, Iowa Maize, amaranth, oil-seed brassicas (e.g., rape, canola, mustard), sweet clover, cucumber, pumpkin, summer squash, acorn squash, zucchini, gourds, beet, carrot, sunflower, millets National clonal germplasm repository Corvallis, Oregon Filberts, pears, strawberry, raspberry, blackberry, cranberry, blueberry, mint, hops Davis, California Grape, stone fruits, walnut, almond, pistachio, persimmon, olive, fig, pomegranate, mulberry, kiwi Geneva, New York Grape, apple Miami, Florida, and Mayaguez, Puerto Rico Banana, mango, avocado, Brazil nut, Chinese date, jujube, coffee, cacao, soursop, bamboo, sugarcane, cassava, tropical yam, cocoyam Orlando, Florida Citrus Hilo, Hawaii Macadamia, guava, passion fruit, barbados cherry, breadfruit, jackfruit, pineapple, papaya, lychee, Canarium (pili nut), Guiliema (peach palm), Nephelium (rambutan, pulasan), carambola Brownwood, Texas Pecan, hickory, chestnut Riverside/Brawley, California Citrus and related genera, date Other facilities National Arboretum, Washington, D.C. Woody ornamental species National Small Grains Collection, Aberdeen Idaho Barley, oats, wheat, triticale, rye, rice, Aegilops (wild wheat relatives) Interregional Research Project (IR-1), Sturgeon Bay, Wisconsin Potato Urbana, Illinois Short-season soybean Stoneville, Mississippi Long-season soybean College Station, Texas Cotton
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System FIGURE 2-1 The division of responsibilities for germplasm management in the United States as they are coordinated through the National Plant Germplasm System.
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System Resources Laboratory (NGRL) at the Agricultural Research Service's Beltsville, Maryland, area. Although plant exploration is an important part of the activities of the NPGS, the bulk of its collections have been acquired through exchange. Germplasm received from other collections worldwide accounts for an estimated 75 percent of acquisitions (S. Dietz, U.S. Department of Agriculture, personal communication, June 1989). Not all of the germplasm that enters the United States comes in through the PIO. University researchers, botanical gardens and arboreta, companies, and private individuals all import plants and seed. Much of this material may not be duplicated or documented in NPGS collections. Collections of unique germplasm, much of it privately held and not fully represented in the NPGS, form a considerable reservoir of diversity (Office of Technology Assessment, 1985). For example, groups such as the Seed Savers Exchange maintain heirloom or older varieties of vegetables, fruit, and flowers and distribute them primarily to individuals for personal use rather than for breeding new cultivars (Office of Technology Assessment, 1985; Shell, 1990). Their holdings are generally not part of NPGS collections and are not documented by it. Plant Introduction Office The PIO is responsible for cataloging incoming germplasm accessions, assigning plant introduction (PI) numbers, and distributing new acquisitions to appropriate curators. The PIO publishes an annual inventory, listing the materials that have been assigned PI numbers (e.g., U.S. Department of Agriculture, 1988a,b), and coordinates germplasm exchanges. The PIO may receive germplasm entering the United States for transfer to the appropriate NPGS site or record that a particular site has received such materials. All documentation for accessions is verified at the PIO. A PI number is assigned by the NGRL once passport data are verified. The PIO then distributes the material to appropriate sites. The office also monitors some of the germplasm that enters the United States through avenues outside the NPGS (e.g., industry, botanical gardens, researchers), especially those plants or seeds receiving the attention of plant quarantine. If any of these latter materials are of importance to the NPGS, the importer is contacted by the PIO and invited to provide samples to the appropriate NPGS site or collection. With the aid of the National Program Staff of the ARS, PI numbers are also assigned to new crop varieties, parental and advanced breeding
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System TABLE 2-2 Number of Plant Introductions into the United States, 1898 –1987 Date a Number of Accessions Received Number of Accessions in GRIN b Percent Percent of Total Received that Is Listed in GRIN b 1898 to 1899 4,274 26 0.6 0.6 1900 to 1909 22,196 187 0.8 0.8 1910 to 1919 22,653 637 2.8 1.7 1920 to 1929 33,476 2,826 8.4 4.5 1930 to 1939 52,136 5,910 11.3 7.1 1940 to 1949 51,060 16,951 33.2 14.3 1950 to 1959 76,883 28,237 36.7 20.9 1960 to 1969 84,185 50,187 59.6 30.3 1970 to 1979 90,127 70,365 78.1 40.1 1980 to 1987 77,285 77,284 99.9 49.1 a A formal germplasm management effort began in the United States in 1948. b Germplasm Resources Information Network. SOURCE: Unpublished data supplied by the U.S. Department of Agriculture,Plant Introduction Office, July 26, 1987. lines, and even genetic stocks that are registered by public and private plant breeders. Registrations for agronomic crops that document origin and important traits of a particular material may be published in Crop Science (Burgess, 1971; White et al., 1988). lines, and even genetic stocks that are registered by public and private plant breeders. Registrations for agronomic crops that document origin and important traits of a particular material may be published in Crop Science (Burgess, 1971; White et al., 1988). Not all of the germplasm in the NPGS is assigned a PI number. Each collection site may maintain materials it received through channels other than that of the PIO. Currently, of the more than 372,000 accessions listed on the GRIN database about 70 percent are identified by PI numbers. Most of the balance carries identification numbers assigned by the NPGS sites. Since 1898 more than 500,000 accessions have been received by the PIO (Table 2-2). Before the late 1940s, introductions went directly to interested researchers or breeders without any requirement that they be maintained beyond their usefulness to the individual. Duplicate or back-up samples were not held by the USDA since no facilities for that purpose existed until 1948. Consequently, most germplasm accessions obtained before 1948 are no longer available. However, many important breeder's lines and cultivars contain genes derived from them. Since 1948, an increasing proportion of germplasm introductions have become part of the NPGS collections and are listed on the GRIN (Table 2-2).
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System Plant Exploration Government-sponsored exploration for the purpose of collecting new germplasm is coordinated through the NGRL. The primary mission is the planning and implementing of plant explorations, especially in foreign areas (Purdue and Christenson, 1989). Plant exploration is a deliberate effort by the NPGS to seek and acquire specific kinds of germplasm. Exploration proposals may be developed by one or more individual researchers who submit a formal proposal through the appropriate crop advisory committee, which is an NPGS advisory group specific to a crop. Scientists need not be employees of USDA or the national system to make such requests. Alternatively, proposals may be developed by a crop committee, the NGRL, or ARS National Program Staff. Once proposals are approved, qualified scientists undertake the exploration. Some U.S. scientists conduct explorations using funds from other government sources, such as the National Science Foundation (NSF), or in cooperation with botanical gardens or arboreta. These activities The grasses native to the Altai region of the south central Soviet Union are surveyed as part of an effort to collect wild rye species for U.S. germplasm collections. Credit: U.S. Department of Agriculture, Agricultural Research Service.
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System support botanical research, plant conservation, or other goals that may be unrelated to the perceived needs of the NPGS. Exploration can also be accomplished through cooperation with individuals or organizations outside the United States. The NPGS occasionally cooperates with the International Board for Plant Genetic Resources (IBPGR) to collect materials of mutual interest. Cooperative exploration almost always involves scientists within the country where exploration occurs. In accordance with IBPGR practice, duplicate samples of collected germplasm are provided to germplasm collections within the country of origin. National Plant Germplasm Quarantine Center When germplasm is acquired from other areas or regions, pests or pathogens may be introduced that could endanger domestic agriculture. Quarantine regulations are intended to reduce this risk, but they are not intended to facilitate the movement and entry of germplasm into the country. The role of expediting the quarantine process falls to the National Plant Germplasm Quarantine Center in Beltsville, Maryland, which recently was subsumed within the NGRL. The center represents a cooperative effort of the Animal and Plant Health Inspection Service (APHIS) and the ARS. ARS scientists and technical personnel provide expertise to propagate materials under quarantine and to test them for the presence of pathogens and other pests of quarantine significance. APHIS scientists and personnel certify such materials for release once quarantine regulations have been satisfied. Interregional Research Project-2 Obtaining pathogen-free, healthy plants for a number of clonally propagated crops, particularly fruit trees, can require years of quarantine. For this reason selected materials are maintained as virus-free clones that can be distributed without the delay associated with lengthy quarantine. The Interregional Research Project-2 (IR-2), located in Prosser, Washington, functions as a national center for virus-free cultivars of deciduous fruit trees and selected ornamentals. It maintains more than 1,000 virus-free cultivars and holds the only known virus-free clones of a few germplasm materials. The IR-2 collections consist primarily of commercially important cultivars for use by researchers and industry. The program also develops methods for detecting and eliminating viruses
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System from infected fruit tree cultivars. IR-2 maintains primarily the stocks of current importance for fruit production; it is not considered by many people to be a part of the NPGS. CONSERVATION After acquisition by the NPGS, accessions are sent to the appropriate curator or collection for conservation. Conservation activities include increasing the sample size through grow-out if there are few seeds or plants, maintaining the material to preserve its genetic integrity, and ensuring that there is sufficient material for use. In general, two kinds of conservation collections exist. Active collections, such as those at the regional plant introduction stations, multiply the material and are the primary sites for its distribution, characterization, evaluation, and general management. Base collections are back-up reserves of the active collections held under conditions of long-term storage. For seeds in the NPGS, base collections are held at the NSSL. For perennial woody plants, and some selected herbaceous species, which are usually propagated asexually, there are no back-up or base collections, and the national clonal germplasm repositories serve as the sites for both active and back-up collections. Active Collections The central elements for managing and maintaining the germplasm of the NPGS are the many active collections throughout the United States. They are responsible for maintaining the germplasm, characterizing and evaluating it, and producing viable seed or planting materials, and they are the primary sources of material for distribution and exchange. The active collections of the NPGS include those of the regional stations and clonal germplasm repositories, and several commodity or special collections (Table 2-1). Other active collections, that are not part of the NPGS, exist in private or institutional collections at colleges, universities, and state agricultural experiment stations. Still other collections are held by industry, nonprofit organizations, botanical gardens, and arboreta. There is no precise information regarding the number, size, or condition of many of these mostly private collections, but it has been suggested that they probably represent a substantial germplasm pool (Office of Technology Assessment, 1985), some of which may be of considerable importance.
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System Regional Plant Introduction Stations Four regional stations have overall responsibility for maintaining the major seed-reproducing species held by the national system. These are the North-Central Regional Plant Introduction Station, Ames, Iowa; the Northeast Regional Plant Introduction Station, Geneva, New York; the Western Regional Plant Introduction Station, Pullman, Washington; and the Southern Regional Plant Introduction Station, Griffin, Georgia (Table 2-3). They are operated jointly by the ARS and state agricultural experiment stations through the Cooperative State Research Service (CSRS). Collectively, they hold approximately 135,000 accessions of nearly 4,000 species. As originally envisioned in the 1940s and 1950s, the regional stations were established to meet the germplasm needs of plant breeders and other scientists. They were to provide foreign and native plant germplasm to crop scientists, preserve and evaluate introduced materials, and serve as holding facilities for the nation's genetic resources. Their responsibilities were based mainly on the concerns of agriculture in A field area at Central Ferry, Washington, on the Snake River is operated by the Western Regional Plant Introduction Station and used for germplasm regeneration, evaluation, testing, and maintenance. Credit: U.S. Department of Agriculture, Western Regional Plant Introduction Station, Pullman, Washington.
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System each of their respective geographic regions. As each station was established, it was incorporated into the ongoing federal plant introduction system, which in the late 1940s was headquartered at the Beltsville (Maryland) Agricultural Research Center. Site selection was based in part on accessibility, facilities, and by joint agreement of the directors of the respective state agricultural experiment stations and the ARS. It was agreed that the experiment stations would provide land, assist in establishing laboratories, greenhouses, and related facilities, and provide office space for staff. The ARS and CSRS supplied most of the funds for equipment, operating expenses, and staff. In addition to the regional stations, four federal plant introduction stations were active during the 1940s and 1950s. Since then their status has changed. The station at Glenn Dale, Maryland, served as an introduction station and national quarantine center. It is being phased out during the 1990s. The station at Miami, Florida, was responsible for subtropical crops, particularly fruits, rubber, cacao, and coffee. One of the earliest introduction stations, it has now become one of the clonal germplasm repositories and continues to maintain its earlier collections. The facility at Savannah, Georgia, held accessions of bamboo, sweet potato, and several other crops, but it is no longer a federal plant introduction station. Its germplasm was transferred to other sites. The station at Chico, California, held germplasm of deciduous tree fruits and nuts adapted to semi-arid conditions and has since been closed. A portion of its accessions were transferred to clonal germplasm repositories. The regional stations receive and distribute germplasm for most of the species that can be stored as dry seed. Thus, they maintain the active collections for much of the seed material in the national system. They are responsible for seed increase and for depositing back-up samples in the base collections of the NSSL. Curators at regional stations interact regularly with users concerning management and use of the species for which they have responsibility. Curators also characterize and evaluate germplasm, but such activities can be limited by insufficient funding or staff. National Clonal Germplasm Repositories The clonal repositories (Table 2-4) contain active collections that hold and propagate agriculturally important germplasm, such as strawberries, raspberries, fruit trees, coffee, and nuts, that for a variety of reasons are not usually held in active collections as seed. Eight repositories are distributed over 10 sites, which together hold more than 27,000 acces-
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System or from a third party, often on an unsupervised contract or cooperative basis. Regeneration techniques should be designed to minimize changes in the relative abundance (frequencies) of genes within an accession. Under the extremes of drought, cold, or disease, for example, some individuals in an accession could survive or even thrive, while others would die, resulting in changes in the overall genetic composition of the sample (i.e., genetic shift). Because of the small population size of an accession, random genetic change (i.e., genetic drift) can also have a major effect. To prevent these genetic changes, parental populations of 100 to 200 plants are grown in an environment to which they are adapted to avoid unintended selection. Other protocols call for the use of multiple sites in varying environments or over succeeding years. Nonetheless, genetic changes may occur during the replenishment of aging seed through inadvertent selection during regeneration and seed aging (Roos, 1984a,b). Methods of storage and testing that reduce the frequency of regeneration are particularly important. No procedure ensures that samples returned from regeneration have the same genetic composition as those that were sent out. New techniques, such as the comparison of gene frequencies before and after regeneration using restriction fragment length polymorphisms, or older technologies such as electrophoretic analysis of seed proteins, could provide some measure of assurance. The common practice is to assume that seed for regeneration has been grown correctly and protected from genetic change or contamination. Clonal crops have specific requirements for germplasm maintenance and increase. Temperate tree fruits may require isolation to prevent loss due to pests or diseases. Screened area protection, quarantine isolation, and standard orchard management practices are among the methods employed. Specific environments may also be needed to ensure the normal development of plants or fruit. Herbaceous plants, such as potatoes, may require greenhouse culture, specific propagation methods, or unique cultural practices. As a consequence, clonal repositories can be very costly. Distribution Distribution of germplasm to researchers and breeders in the United States and throughout the world is an important part of the activities of the national system (Table 2-11). Germplasm requests to the NPGS from outside the United States (except those from Canada) are processed through the Plant Introduction Office. Distribution for U.S. and Cana-
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System TABLE 2-11 Germplasm Distributions from Seed Collections and Clonal Repositories of the National Plant Germplasm System to Various Users, 1980–1989 United States Year Private State Federal USAIDa Foreign Privatea Foreign Publicb International Centers Annual Total 1980 14,349 57,463 60,197 660 3,449 35,649 4,880 176,647 1981 13,856 49,491 47,104 85 3,788 65,269 8,774 188,368 1982 21,086 55,431 43,982 116 2,332 47,350 7,481 187,778 1983 12,355 63,907 76,768 2,238 3,948 36,269 4,715 200,200 1984 17,596 82,787 175,838 249 3,855 20,313 2,915 309,553 1985 20,941 103,558 94,743 578 1,985 25,874 1,345 249,024 1986 13,787 49,502 76,331 388 3,658 16,697 3,546 163,909 1987 11,471 39,668 86,302 216 13,154 28,938 3,409 183,158 1988c 18,736 44,934 56,656 56 3,579 22,176 3,348 149,485 1989 28,575 86,306 84,909 2,590 5,253 14,882 7,809 230,324 a Distributions were made through the U.S. Agency for International Development (USAID) to 36 countries in 1987. b Distributions were made to 104 countries in 1987. c Distributions for 1988 declined because distributions from the National Small Grains Collection were deferred while the collection was being moved from Beltsville, Maryland, to Aberdeen, Idaho. SOURCE: Unpublished data supplied by U.S. Department of Agriculture,Plant Introduction Office, April 10, 1990.
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System dian requests is done by the appropriate collection. A considerable amount of germplasm, particularly genetic stocks and breeding lines, is directly exchanged between scientists. The PIO coordinates most of the international transfer of germplasm by the national system. In cooperation with the responsible active collection or curator, the PIO staff might work to determine which materials are appropriate to fill a request too large to be of practical use (e.g., a request for all of the accessions of a crop that may number in the thousands). Where quarantine regulations require certification or declaration of phytosanitary status of the material, the PIO, in cooperation with APHIS, completes the needed paperwork. This is frequently accomplished at the local level by qualified state or federal personnel. Germplasm is not distributed from the NSSL unless it is unavailable from active collections or elsewhere in the NPGS. In this case, the NSSL generally sends the seed to an appropriate active collection site or the original supplier of the germplasm for regeneration. In cases of extreme need or emergency and if sufficient seed is available, the NSSL may distribute samples directly to users. If it is necessary to regenerate samples, distribution of requested germplasm can be delayed for months or, more rarely, years. The number of seeds distributed depends on the species and the amount available in storage. In general enough seed is sent for the user to grow a row approximately 15 meters (50 feet) long. From this, requesters are expected to reproduce additional seed. Individuals requesting seed for personal use, as in gardens, are generally referred to other sources. Recipients of NPGS germplasm are asked to acknowledge its source in reports and publications, and to report performance or evaluation information to the NPGS curator for that crop. Characterization and Evaluation To be useful and accessible to breeders and researchers, information about the germplasm in a collection should be well described for specific characters and should indicate origin. It will enable users to know which accessions are likely sources for particular genetic traits. The maintenance of this information in a retrievable form is referred to as documentation. Passport data provide the basic documentation, including taxonomic designation and information about where an accession was collected. These data are provided by the collector or donor institution. They are reviewed upon arrival at the PIO and entered into the database record when a PI number is assigned by that office. Unfortunately, such minimal data are not readily available for many of the accessions of the
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System NPGS, particularly those received before 1978. While passport data do exist for many accessions, the NPGS has been slow in adding this information to its computerized database. Characterization involves the assessment of a varying number of descriptors ranging from morphological to biochemical. These descriptors, intended to describe an accession in relation to others in the collection, are determined by crop advisory committees and curators. The information can be gathered by the curators of active collections as materials are regenerated or assessed by cooperating scientists during evaluation for resistance to disease, environmental responses, or other traits. The gathering of crop descriptor data is an important part of the work of regional stations, repositories, and commodity collections because such data better define germplasm holdings and aid re-identification during regeneration. Evaluation is a lengthy, often repetitive process of examining accessions for traits of significance to potential users. Screening for disease resistance is an example. It may take many years to test all of the accessions for a very large collection in a sufficiently wide range of environments. Although preliminary evaluation for genetically stable traits is generally considered an NPGS activity, more detailed evaluation for characters such as disease resistance or production qualities is generally part of the research that accompanies a breeding program. In a few cases, such as alfalfa at the western regional station, NPGS sites have funded researchers at other locations to conduct evaluations. Private companies and other users of NPGS germplasm also evaluate material, and the NPGS has occasionally provided funds for evaluating certain traits. The Soil Conservation Service (SCS) also cooperates with the NPGS through a memorandum of understanding with the ARS to perform evaluations on certain materials. One purpose of the SCS is to foster acquisition, evaluation, and distribution of plants important to soil and water conservation. Documentation The usefulness of new accessions depends on the user being able to retrieve information about them. In 1977 ARS recommended setting up a central repository for genetic resources information with standardized crop descriptors that would improve the management of NPGS collections (Mowder and Stoner, 1989). The Germplasm Resources Information Network manages all of the data associated with acquisition, evaluation, regeneration, inventory, and other records of the NPGS collections. It
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System is a centralized computer database for managing and operating the national system and for informing scientists and other users about the location and characteristics of NPGS germplasm (Database Management Unit, 1987). The GRIN runs on a Prime 9955 Model II computer and uses a software package and database management system distributed by Prime Computer, Inc. Additional programs are written to meet specific needs. This system is transportable only to other, compatible Prime computers. Smaller portions of the data can be formatted for use on microcomputers using commonly available software packages. Searches of the database with printed results can be requested. The GRIN holds three kinds of information. Passport data are recorded by the PIO when the PI number is assigned. They include the name of the collector, collection site data, taxonomy, and collection longitude, latitude, and elevation. Characterization and evaluation data are of value to potential users and include general plant descriptions, agronomic responses, disease and insect pathogen susceptibility or resistance, quality, and yield. Finally, the GRIN provides inventory and seed request processing data to NPGS sites as an aid to managing their collections. While administering the network is the responsibility of the GRIN staff in Beltsville, Maryland, most sites also have personnel trained to enter their evaluation and other site data directly into the network. UTILIZATION The NPGS centers, for the most part, do not develop new cultivars or improve breeding materials. Nonetheless, a considerable amount of public funds are dedicated to germplasm enhancement, or the transfer of useful traits into an agronomically appropriate genetic background. For some commodity collections at experiment stations or universities, germplasm conservation may be an adjunct to enhancement. Many public institutions are involved in germplasm enhancement. State agricultural experiment stations, public and private colleges and universities, and private industry use NPGS collections for breeding and enhancement to produce improved parental materials. Breeders do not use these collections frequently, but find them invaluable for particular genetic characters not readily available to them (Duvick, 1984; Peeters and Galwey, 1988). For example, the appearance of the Russian wheat aphid in the United States in 1986 caused more than $130 million in losses to grain crops in 1988 (Peairs et al., 1989). An immediate search for host plant resistance in the national wheat collection has already revealed some promising sources of resistance.
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System Russian wheat aphids feed on wheat leaves, which then roll and impede the effectiveness of conventional pesticide applications. Genetic resistance to the aphid is found in some barley, rye, wheat, and forage grass germplasm and in a few wild species related to wheat. Credit: U.S. Department of Agriculture, Agricultural Research Service. Colleges, Universities, and the National System Colleges and universities have made much use of germplasm for breeding and basic research with the aid of public sector funds. Although the private sector now plays a major role in producing modern varieties of such food crops as corn, sorghum, and soybeans, it is unlikely to assume a larger role in evaluating basic germplasm stocks. Scientists in public and private colleges and universities have contributed to genetic resources activities, including plant exploration, evaluation, and regeneration. For some investigators, the USDA has provided funds for specific research tasks. Other federal agencies (e.g., NSF) have sponsored the work of university scientists on germplasm evolution, population genetics, taxonomy, and physiology. Examples include the collections of maize assembled in the 1940s by E. Anderson and H. C. Cutler of Washington University and P. C. Manglesdorf of Harvard University; A. F. Blakeslee's Jimson weed (Datura) collection; and R. E. Cleland's Evening Primrose (Oenothera) collection, which provided benchmark studies in cytology and cytogenetics. The maize collections of Anderson, Cutler, and Manglesdorf were
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System built on the remnants of an earlier collection developed by G. N. Collins and J. H. Kempton of the USDA and then left to languish. Similar examples can be cited for tomatoes, barley, peas, and their wild relatives. The NPGS has recently begun to assist in developing and maintaining several of these old, long-used collections. Recently the NPGS has been able to support non-USDA curators of selected germplasm collections. These arrangements should reduce the probability of losing such valuable resources. They allow collections to be managed by researchers with specific knowledge of their contents who can use specialized techniques that may be necessary for maintenance. However, it is important to survey and inventory many other collections, before they are lost. The NPGS is attempting to do this (H. L. Shands, U.S. Department of Agriculture, personal communication, September 1989). In general, the record of accomplishments of university scientists is excellent. Many of their collections were incorporated into USDA SORGHUM PI 264453 Sorghum bicolor Moench GRIN Data Origin: Spain Acquisition: Spain PI assigned: 1960 Maintenance site: Southern Regional Plant Introduction Station Greenbug damage can be compared on sorghum hybrids (left) with and (right) without genetic resistance to the insect. Credit: A. Bruce Maunder. It may fairly be asked why large collections of germplasm should be maintained when an individual accession may be used only rarely, if ever. The value of a collection lies not in the frequency of its use, but in the resource it provides when, and if, it is needed. It is thus not surprising that some accessions may possess genetic traits that remain unknown or unrecognized for many years, but which later prove to be almost invaluable. In 1980, motivated by the threat of a new outbreak of greenbug (Schizaphis graminum) in the U.S. sorghum crop, scientists began to screen sorghum accessions in search of genes for resistance. An outbreak of a
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System collections, but some remain at risk. Increasing emphasis on molecular biology and genetic engineering at universities and colleges has raised concern about the declining interest in breeding, taxonomy, and evolutionary studies that could lead to abandonment of important collections. Recognition of the national importance of research on genetic resources has led to greater USDA-ARS support of at least some of these programs and scientists. There must be broader opportunities for the NPGS to harness the expertise of scientists in colleges and universities. Private Industry and the NPGS Chemical and pharmaceutical companies have supported plant collection activities to find new plant products. Pyrethrum from species of Chrysanthemum and anticancer compounds from Vinca species are examples. However, once the effective compound is isolated, identified, mutant (new biotype) greenbug on sorghum in the 1960s and early 1970s had cost U.S. farmers more than $100 million in 1968 alone. Varieties of sorghum with resistance to the more common greenbug were eventually developed, but they were defenseless against the new form of the insect. The new biotype, like the earlier one, migrates from wheat and kills by injecting a poison into the plant's tissue. Resistance to this new greenbug infestation was needed and was found in PI 264453, a cultivated variety of sorghum that had been introduced to the United States from Cordoba, Spain, in 1960. Its origin was most likely Africa, where all sorghums are thought to have originated. Shortly after introduction, this accession was found to be resistant to other greenbug infestations. It was not until 1980, however, that it was found to be one of the few germplasms tested that had resistance to this new outbreak. Several commercial sorghum hybrids now possess the genes for greenbug resistance from PI 264453. The United States produced 741 million bushels of sorghum in 1987, worth about $1.2 billion. It is estimated that about 1 million acres of sorghum annually are protected in the United States through this genetic improvement. Without a broad collection to search for greenbug resistance, locating the genes to provide protection would likely have been a much lengthier, more difficult, and uncertain task. “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 A. Bruce Maunder, DEKALB Plant Genetics.
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System and synthetically reproduced, there may be little economic incentive for the companies to maintain the germplasm. The confectionery, perfume, beverage, and specialty food industries are interested in exotic plants and plant products. On occasion, these industries have funded collections of particular genera or species. Collections produced by these activities, however, generally do not become part of the NPGS. A few, large U.S. seed companies, by contrast, have often contributed to the national system. These companies have regenerated collections in field plots for the NPGS. By growing materials obtained from many countries in a disease-free environment, the seed produced can be assured to be safe for importation. The multinational research programs of some seed companies have thus been used to meet the needs of U.S. genetic resources conservation and development. PLANT GERMPLASM ACTIVITIES OUTSIDE THE NATIONAL SYSTEM Botanical Gardens and Arboreta Botanical gardens and arboreta are primarily intended to meet local needs. Their forms and functions may range from university gardens with academic and public service responsibilities, to privately sponsored gardens that are governed by a board of directors. They may or may not have research capabilities. Although many were centers of plant introduction (Plucknett et al., 1987), they are no longer primary repositories of crop genetic resources. They have become increasingly concerned with conserving wild plant species, particularly those that are rare or endangered. On a global basis this has been encouraged by the International Union for Conservation of Nature and Natural Resources (Bramwell et al., 1987) through its Botanic Gardens Secretariat. The Center for Plant Conservation (CPC), an association of U.S. botanical gardens, maintains rare and endangered U.S. plant species. Cooperating gardens acquire and maintain plants or seeds of these species in their respective regions. The NPGS helps the CPC by providing back-up storage of seeds for its collections at the western regional station and at the NSSL. The CPC's collections are not, however, part of the NPGS. Nongovernmental Activities and Private Collections Farmers, gardeners, and hobbyists have become important conservators of old, obsolete, or heirloom varieties of vegetables, fruits, and
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System The diversity of heirloom varieties of winter squash is shown in the collections of the Seed Savers Exchange. Credit: David Cavagnaro. flowers (Office of Technology Assessment, 1985). Grass-roots groups share information, seeds, and plant materials. For example, the North American Fruit Explorers brings together people interested in conserving antique or heirloom fruit and nut varieties. A more organized effort, the Seed Savers Exchange (SSE), maintains a large collection of its own, forms networks of gardeners around the country, and publishes several books related to conserving heirloom genetic resources (Office of Technology Assessment, 1985). Native Seeds/SEARCH (Southwestern Endangered Aridland Resource Clearing House) in Tucson, Arizona, seeks to integrate cultural and biological resources in an effort to conserve locally adapted crops and wild species through in situ and ex situ efforts. Such groups are not formally part of the NPGS, but they may hold valuable germplasm not in its collections. The SSE is one of the largest and most active nongovernmental groups that preserve plant genetic resources. It is based on a small farm in rural Iowa and depends on individuals who maintain seeds of numerous obsolete heirloom varieties of vegetables and crops. Like the NPGS, the SSE recognizes the problems of duplication, inconsistencies in nomenclature, contamination, inadvertent crossing between varieties, and record keeping. It has developed a database system, trained curators,
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MANAGING GLOBAL GENETIC RESOURCES: The U.S. National Plant Germplasm System and produced a variety of written instructional materials. The Garden Seed Inventory (Seed Savers Exchange, 1989a) lists all nonhybrid seeds offered for sale by mail-order seed companies in the United States and Canada. It itemizes cultivars that are decreasing in availability and encourages readers to preserve them in their gardens. SSE also has produced a similar listing for fruit, berry, and nut crops available by mail order in the United States (Seed Savers Exchange, 1989b). Nongovernmental collections generally differ from those of the national system. The SSE preserves old, obsolete, open-pollinated vegetable varieties not available commercially. Active members will often select materials to assure that the desired type is maintained, rather than to preserve genetic diversity. “Off” types are culled rather than preserved for the unusual or rare genes they may possess. Seed is produced every 1 to 3 years and is thus subject to regular environmental selection pressures each time a seed increase is made. In contrast, NPGS accessions are meant to be preserved without genetic change and are held as the basis for breeding and research activities. Thus NPGS collections generally contain a greater proportion of wild species, landraces, and breeding lines. Regeneration and storage methods are designed to reduce the number of times regeneration is needed. The SSE focuses on preserving the general, visually discernable characteristics of an accession, whereas the NPGS is more concerned with preserving all of its genes. The Living Historical Farms also holds a variety of germplasm. These collections can be sources of old, obsolete varieties that are no longer commercially available. Recent interests in specialty vegetables has raised awareness of many older varieties and led to their commercial use. The genetic resources maintained by many of these collections are at risk and are not always readily available for research purposes. They should be part of the national collections. Accuracy of nomenclature, authenticity, uniqueness, the extent of internal duplication, and overlap with existing national collections should be determined and assessed. Limited budgets, facilities, and personnel will constrain this work, but these collections should be encouraged and assisted. The NPGS agreement to provide back-up storage for CPC collections is an example of this cooperative effort.
Representative terms from entire chapter: