National Academies Press: OpenBook

The U.S. National Plant Germplasm System (1991)

Chapter: 2 Elements of the National Plant Germplasm System

« Previous: 1 Managing Crop Genetic Resources
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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,

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

FIGURE 2-1 The division of responsibilities for germplasm management in the United States as they are coordinated through the National Plant Germplasm System.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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).

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
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.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
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.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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-

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

TABLE 2-3 Overview of Holdings and Facilities at Sites and Collections, Excluding the National Clonal Germplasm Repositories

         

Facilities

Site or Collection

Year of Origin

Number of Species

Number of Accessions

Number of FTE Staffa

Cold Storage (ft3)

Greenhouse (ft2)

Field Area (acres)

Lath or Screenhouse (ft2)

Regional plant introduction stations

 

Western

1952

1,828

41,200

19.75

21,400

18,000

64

2,493

Southern

1949

1,320

58,031

23.0

16,000

16,409b

8

3,108

Northeast c

1948

256

15,182

9.7

319

8,442

44

19,564d

North-Central

1948

760

23,800

19.0e

10,500

9,300

120

3,600

National Small Grains Collectionf

1894

101

110,738

8.0

44,000

2,720

25

 

Interregional Research Project-1 (IR-1), potato

1947

115

4,600

6.0

4,400

7,200

10

9,000

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

Soybean, long season

1948

1

3,716

5.3

4,464

600

10

18,000

Soybean, short season

1949

14

9,440

4.5

450

300

8.5

1,500

Cotton

1955

40

5,558

3.0

2,723

3,672

g

839

National Seed Storage Laboratory

1958

1,848

232,000

26.0

30,000

5,000

0

0

NOTE: Data are from 1988 and were supplied by individual sites, unless otherwise noted. N.A. = Not applicable.

a FTE staff = full-time equivalent staff.

b Includes about 12,000 square feet added during October 1989.

c A national clonal germplasm repository has separate facilities at this site, as described in Table 2-4

d Includes barns, field laboratory, and seed cleaning, threshing, and drying spaces.

e Does not include 40 part-time, hourly positions.

f Data for 1988 were not available during the facility's relocation to Aberdeen, Idaho, from Beltsville, Maryland; the data were provided in 1989.

g Field areas are obtained through contract.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

TABLE 2-4 Overview of Holdings and Facilities at the National Clonal Germplasm Repositories, 1988

       

Facilities

Repository Sitea

Year of Originb

Number of Species

Number of Accessions

Number of FTE Staffc

Cold Storage (ft3)

Greenhouse (ft2)

Field Area (acres)

Lath or Screenhouse (ft2)

Brownwood, Texas

1984

16

853

2.2

560

2,830

79

Corvallis, Oregon

1981

597

5,276

11.0

5,221

9,800

20

17,850

Davis, California

1981

142

6,572

6.0

3,500

2,400

70

5,200

Geneva, New Yorkd

1984

60

3,700

4.8

2,300

1,800

50

900

Hilo, Hawaii

1987

35

535

4.25

118

1,800

10

3,000

Orlando, Florida

1988

31

400

1.0

0

1,400

10

1,800

Miami, Florida

1984

1,516

8,000

11.0

0

10,000

200

3,200

Mayaguez, Puerto Rico

1984

424

1,102

1.0

4,440

128

Riverside, California

1987

119

827

2.5

0

4,800

3

4,800

Brawley, California

1981

2

70

1.0

0

0

4.5

0

NOTE: The data were supplied by individual sites through a survey conducted in the fall of 1988.

a Mayaguez, Puerto Rico, is administered as part of the repository at Miami, Florida. Similarly, Brawley, California, is administered through Riverside, California.

b For Miami, Florida, and Mayaguez, Puerto Rico, the dates refer to the year in which they were designated as repositories. The sites originated in 1923 and 1901, respectively.

c FTE staff = full-time equivalent staff.

d The Northeast Regional Plant Introduction Station has separate facilities at this site, as noted on Table 2-3.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

The characteristics of fruit on an apple germplasm accession are examined at the National Clonal Germplasm Repository at Geneva, New York. Credit: U.S. Department of Agriculture, Northeast Regional Plant Introduction Station, Geneva, New York.

sions. Accession decisions are generally made following consultation with public and private sector representatives, crop advisory committees or technical advisory committees, and ARS officials.

The primary responsibilities of the repositories are to collect, identify, propagate, preserve, evaluate, document, and distribute clonal germplasm as part of the NPGS. This includes maintenance of an information file on each accession in the clonal collection (National Plant Germplasm Committee, 1986). For most material held in such collections, long-term storage is not feasible, so duplicate materials are generally maintained in field and greenhouse or screenhouse collections to provide some back-up protection against loss. The repositories are charged with developing active global collections of appropriate wild species and domestic cultivars, and to assemble a maximum level of genetic diversity possible for each genus and species for which they are responsible. They also conduct research to improve evaluation, propagation, characterization, and preservation of clonal germplasm (National Plant Germplasm Committee, 1986).

The national clonal germplasm repositories are intended to carry out the same function for vegetatively propagated crops as that carried out by the regional stations and the NSSL for seed crops. Unlike seeds held

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

at the laboratory, however, backups of clonal collections are limited to the same sites where the active collections are maintained. Many clonal crops can be conserved as seed, but they are impossible to maintain true to type by raising plants from seed. Many clonally propagated species take a long time to mature, and they are best preserved as mature live plants for plant breeding and research.

Clonal collections are expensive to establish, and they have many of the same problems that confront seed collections. Accessions must be maintained as plants in the field, which can require large tracts of land, or in screenhouses or greenhouses. Accessions may also be maintained as live sticks of budwood held under refrigeration or as tissue cultures. There may be losses during maintenance from insects and disease, freezing temperatures, electric power failures, or grazing animals. Clonal preservation is more expensive and labor intensive than seed storage. Clonal collections have been threatened as facility or land-use priorities have changed, as the principal scientists retired, died, or moved, or as funding declined. By establishing the national clonal germplasm repositories, a mechanism for stable, long-term maintenance for many important clonally propagated species has been provided.

Interregional Research Project-1

The Interregional Research Project-1 (IR-1), located in Sturgeon Bay, Wisconsin, began in 1947 and is supported cooperatively by USDA through CSRS and ARS, and by the Wisconsin State Agriculture Experiment Station. It is the national repository for potato germplasm. The station has a collection of about 3,500 accessions of more than 100 wild and Cultivated potato species and is an important global resource.

IR-1 uses a variety of methods to maintain germplasm. True seed of potatoes, in vitro plantlets of selected clones, and tubers are maintained. The germplasm is propagated both for maintenance and distribution.

National Small Grains Collection

The National Small Grains Collection (NSGC) (Table 2-3) began in 1894 as a breeder's collection and is today the most widely used active collection in the NPGS (White et al., 1989). This collection, relocated in 1989 from Beltsville, Maryland, to Aberdeen, Idaho, holds more than 110,000 accessions of wheat, barley, oats, rice, rye, the wheat wild relative Aegilops, and the intergeneric wheat-rye hybrid, triticale. It is one of the world's largest collections with some of its accessions originating from nineteenth century plant explorations. About 100,000

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

samples are distributed yearly from the collection to breeders, researchers, and germplasm collections in the United States and abroad.

Other Crop Collections

Important genetic resources are conserved and maintained at other federal, state, and university sites (Table 2-5). They include several crop

TABLE 2-5 Examples of Special Crop Germplasm Collections at State and Federal Facilities

Crop

ARS (A) or State (S) Facilitya

Location

Bamboo

A

Byron, Georgia

Barleyb

S

Fort Collins, Colorado

Brassica b

S

Madison, Wisconsin

Cabbagec

S

Madison, Wisconsin

Cauliflowerc

S

Madison, Wisconsin

Chickoryb

A

Salinas, California

Clovers

S

Lexington, Kentucky

Cotton (Gossypium barbadense)

A

Phoenix, Arizona

Cotton (G. hirsutum)

A

Stoneville, Mississippi

Endiveb

A

Salinas, California

Flax

A

Fargo, North Dakota

Forage and range grassesb

A

Logan, Utah

Forage grasses

A

Tifton, Georgia

Leafy vegetables

A

Salinas, California

Lettuceb

A

Salinas, California

Linum

A

Fargo, North Dakota

Maizeb

S

Urbana, Illinois

Mustardsc

S

Madison, Wisconsin

Native grasses

S

Brookings, South Dakota

Peab

A

Geneva, New York

Pearl millet

A

Tifton, Georgia

Pennisetum (wild species)

A

Tifton, Georgia

Tobacco

A

Oxford, North Carolina

Tomatob and Lycopersicon species

S

Davis, California

Turnipc

S

Madison, Wisconsin

Trifolium species

S

Lexington, Kentucky

Tripsacum

S

Raleigh, North Carolina

Wheat and related speciesb

S

Columbia, Missouri; Riverside, California

Wild peanuts

A

Stillwater, Oklahoma

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

TABLE 2-6 Survey Results Showing Distinct Plant Genetic Resource Collections and Collections with Nine or More Accessions by Category at State Agricultural Experiment Stations

   

Collections with Nine or More Accessions in a Category

State/ Territory

Number of Collections

Related Genetic Stocks

Wild Species

Land-races

Elite Breeding Lines

Cultivars

Alabama

13

6

5

3

10

8

Alaska

3

2

0

0

0

3

Arizona

9

4

3

4

4

3

Arkansas

22

13

6

4

19

19

California

29

17

10

6

12

19

Colorado

15

6

2

7

5

5

Connecticut

5

2

2

0

2

0

Delaware

1

1

0

0

0

0

Florida

63

24

13

3

22

24

Georgia

18

11

5

4

14

13

Hawaii

24

17

10

5

10

19

Idaho

4

3

2

1

3

4

Illinois

14

10

4

4

10

10

Indiana

11

9

3

5

9

8

Iowa

20

8

4

3

12

11

Kansas

6

5

4

2

5

3

Kentucky

7

6

4

1

7

4

Louisiana

24

13

8

1

13

12

Maine

1

1

0

0

1

1

Maryland

5

0

1

1

3

3

Massachusetts

4

1

1

0

2

2

Michigan

18

10

10

2

14

7

Minnesota

28

16

8

5

24

18

Mississippi

4

1

0

1

2

2

Missouri

9

8

3

3

4

5

Montana

5

4

1

2

3

3

Nebraska

16

11

3

3

9

6

Nevada

NR

NR

NR

NR

NR

NR

New Hampshire

NR

NR

NR

NR

NR

NR

New Jersey

35

6

3

NR

17

21

New Mexico

7

7

3

3

5

4

New York

12

6

4

4

10

8

North Carolina

24

15

14

5

16

16

North Dakota

19

14

6

3

14

13

Ohio

10

9

2

2

7

8

Oklahoma

9

9

1

2

8

5

Oregon

21

9

5

2

12

12

Pennsylvania

13

9

2

1

10

4

Puerto Rico

6

4

0

4

6

3

Rhode Island

NR

NR

NR

NR

NR

NR

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

South Carolina

7

6

2

NR

6

4

South Dakota

11

9

2

2

8

5

Tennessee

7

4

1

2

3

2

Texas

75

51

18

12

41

39

Utah

3

2

2

NR

2

2

Vermont

NR

NR

NR

NR

NR

NR

Virginia

5

3

3

0

4

4

Washington

12

7

5

0

11

7

West Virginia

1

0

1

0

0

1

Wisconsin

36

24

12

8

25

14

Wyoming

5

1

2

0

0

0

Total

696

403

200

121

424

384

NOTE: NR = No response.

SOURCE: Based on responses to a 1988 questionnaire distributed bythe University of California Genetic Resources Conservation Programto plant science departments (including plant pathology, genetics,and agronomy, but not forestry) that were associated with state agriculturalexperiment stations.

species collections, such as soybeans and other legumes, cotton, and grasses. Some crop species, such as the native grasses in Brookings, South Dakota, or clovers in Lexington, Kentucky, are maintained in collections by individuals with particular interests in them or by sites with histories of studying them. Maintenance support is generally provided by the NPGS, or by state or other federal sources. Many of these collections are not duplicated and are primary sources for the materials they hold.

Several colleges, universities, and state agricultural experiment stations (Table 2-6) hold collections of germplasm that support breeding programs or the research interests of individuals. Much of this germplasm was gathered independently and may not be part of NPGS collections. Some of these collections are not listed in any official inventory, because they are small or only used by a few individuals.

The committee could not assess the degree to which these collections, often widely disseminated, duplicate NPGS collections. They may hold proportionately smaller numbers of wild species, landraces, and prim

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

itive materials than NPGS collections, but, as with the Charles M. Rick Tomato Genetics Resource Center (formerly the Tomato Genetics Stock Center), they can be important sources for wild or primitive materials.

Genetic Stock Collections

This report defines genetic stocks as accessions with unique genetic or cytological characteristics that frequently make them of particular value in basic research. They do not include elite or advanced breeders ' lines, in contrast with its definition by the Commission on Plant Genetic Resources of the Food and Agriculture Organization.

Genetic stocks differ from other germplasm stocks in several respects. Genetic stocks carry mutant genes or chromosomal rearrangements, deletions, or additions, and are often difficult and costly to maintain because they require specialized care and trained personnel. Stocks carrying recessive lethal traits must be maintained as hybrids. Cytological screening (chromosome examination) is needed to verify stocks with chromosomal abnormalities. Also, mutant stocks with lethal or deleterious genes often have short-lived seeds. These traits are often maintained in special genetic backgrounds or as groups of linked genetic markers.

Many genetic stock collections receive partial support from USDA through the ARS and from state sources. The NSF has been an important source of support, but it no longer funds maintenance of collections.

Genetic stock collections commonly held by the individuals or groups who developed them can be difficult to maintain because of their unique nature and frequently complex cytogenetics. Such collections are too easily lost when the person responsible for them moves on or retires. The NPGS has made efforts to determine where genetic stock collections are, to monitor them, and in some cases to provide funds through the ARS for maintenance.

The importance of genetic stock collections to crop development is well illustrated by the Charles M. Rick Tomato Genetics Resource Center at the University of California at Davis (Genetic Resources Conservation Program, 1988). The ARS provides partial support to the center, and an endowment fund has been established to support its work. It holds 2,750 accessions, about 1,000 of which are wild species related to the cultivated tomato. These wild species are important sources of resistance to 28 tomato diseases and pests ( Table 2-7), as well as tolerance to other environmental stresses, such as temperature extremes, salinity, drought, and waterlogging. The tomato has also become a popular research model system in molecular studies of higher plant genomes. The detailed

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

linkage map of the tomato genome was largely developed using the center's stocks.

TABLE 2-7 Economically Important Diseases of Cultivated Tomato to Which Wild Lycopersicon and Solanum Species Have Contributed Sources of Resistance

Disease or Pest

Responsible Organism

Source of Resistance

Fungi

   

Collar rot

Alternaria solani

L. hirsutum, L. peruvianum, L. pimpinellifolium

Leaf mold

Cladosporium fulvum

L. esculentum var. cerasiforme

Anthracnose

Collectotrichum coccodes

L. esculentum var. cerasiforme

Target leaf spot

Corynespora cassiicola

L. pimpinellifolium

Didymella canker

Didymella lycopersici

L. hirsutum

Fusarium wilt

Fusarium oxysporum f. sp. lycopersici

L. pimpinellifolium

Phoma blight

Phoma andina

L. hirsutum

Late blight

Phytophthora infestans

L. pimpinellifolium

Phytophthora fruit rot

Phytophthora parasitica

L. pimpinellifolium

Phytophthora root rot

Phytophthora parasitica

L. esculentum var. cerasiforme

Corky root

Pyrenochaeta lycopersici

L. peruvianum

Septoria leaf spot

Septoria lycopersici

L. esculentum var. cerasiforme, L. hirsutum, L. pimpinellifolium

Gray leaf spot

Stemphylium solani

L. pimpinellifolium

Verticillium wilt

Verticillium albo-atrum

L. esculentum var. cerasiforme

Dahlia wilt

Verticillium dahliae

L. peruvianum

Bacteria

   

Bacterial canker

Corynebacterium michiganese

L. hirsutum, L. peruvianum, L. pimpinellifolium

Bacterial speck

Pseudomonas tomato

L. pimpinellifolium

Bacterial wilt

Pseudomonas solanacearum

L. pimpinellifolium

Bacterial spot

Xanthomonas vesicatoria

L. esculentum var. cerasiforme

Nematodes

   

Potato cyst nematode

Globodera pallida

L. hirsutum

Sugarbeet nematode

Heterodera schactii

L. pimpinellifolium

Root-knot nematode

Meloidogyne incognita

L. peruvianum

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

Viruses

   

Cucumber mosaic

Cucumber mosaic virus

L. peruvianum, S. lycopersicoides

Curly top

Beet curly top virus

L. peruvianum

Veinbanding mosaic

Potato Y virus

L. esculentum var. cerasiforme

Spotted wilt

Tomato spotted wilt virus

L. pimpinellifolium

Tobacco mosaic

Tobacco mosaic virus

L. peruvianum

Tomato yellow leaf

Tomato yellow leaf curl virus

L. cheesmanii, L. hirsutum, L. peruvianum, L. pimpinellifolium

SOURCE: Rick, C. M., J. W. DeVerna, R. T. Chetelat, and M. A. Stevens. 1987. Potential contributions of wide crosses to improvement of processing tomatoes. Acta Horticulturae 200:45–55.

Some genetic stock centers are expanding to include the maintenance of cloned DNA (deoxyribonucleic acid) sequences for use as molecular markers (restriction fragment length polymorphisms) and as specifically cloned genes. As these technologies develop and are increasingly used in research and breeding, the NPGS will have to consider how best to manage the data and DNA.

National Arboretum

The National Arboretum, established in 1927 in Washington, D.C., by an act of Congress, is primarily concerned with research and public education on trees, shrubs, and related plants. It maintains its own herbarium (separate from the National Herbarium of the Smithsonian Institution) of more than 500,000 dried specimens with emphasis on economic and cultivated plants, including voucher specimens from USDA plant explorations. It cooperates closely with NPGS on an informal basis. An ARS plant germplasm staff person at the arboretum has the primary responsibility of developing a germplasm collection of woody landscape species.

The arboretum has an active worldwide germplasm collection program and distributes materials to users in both the public and private sectors.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

It maintains about 60,000 accessions, primarily of ornamental trees and shrubs. Most are conserved as plants in outdoor plantings and in screenhouses or greenhouses. The arboretum has introduced many widely used ornamental plants. For example, the popular ornamental crapemyrtle hybrids, resistant to the powdery mildew fungus, were developed and introduced by the National Arboretum.

Base Collections

Some NPGS genetic resources are also held in base collections in long-term storage as a reserve to the active collections. If samples in active collections are no longer available or cannot be regenerated, the germplasm held in the base collection can be used to replace them.

Dried specimens of woody plants are among the materials held in the herbarium of the National Arboretum, Washington, D.C. Credit: U.S. Department of Agriculture, Agricultural Research Service.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

Germplasm in a base collection must be maintained under conditions that promote long-term storage. For seeds this generally entails maintenance at low temperatures and low relative humidity. It may also include cryopreservation (storage in or suspended above liquid nitrogen between −150°C and −196°C) of seeds, pollen, in vitro cultures, or dormant buds, in the case of clonal germplasm.

National Seed Storage Laboratory

The NSSL is the principal site of long-term seed storage of genetic resources in the United States (see Table 2-3). It provides base collection storage facilities for the national system and holds samples of other important seed accessions (Table 2-8). Consideration is being given to storing cell and tissue cultures, pollen, and DNA.

CRAPEMYRTLE

PI 237884

Lagerstroemia fauriei

Koehne

GRIN Data

Origin: Unknown

Acquisition: Japan

Common name: Crapemyrtle

Year PI assigned: 1957

Specimens of Lagerstroemia fauriei can be found at the National Arboretum, Washington, D.C. Credit: U.S. National Arboretum.

A wild species (Lagerstroemia fauriei), related to the popular ornamental tree, crapemyrtle (L. indica), illustrates the importance of wild plants as germplasm for improving and protecting horticultural plants.

On November 26, 1956, when Dr. John Creech collected seeds of L. fauriei from its native habitat near a rocky streambed at an elevation of 1,000-feet (300 meters) on the small Japanese island of Yakushima, the common crapemyrtle was already

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

The NSSL currently holds in excess of 230,000 accessions of more than 1,800 species. It also holds reference specimens of germplasm registered through the Crop Science Society of America, and it is the sole site for some genetic stock collections such as the Jimson weed (Datura) collection of A. F. Blakeslee, important to early studies of chromosomes and plant development. Seed samples of plant varieties protected under the Plant Variety Protection Act are also held by the NSSL.

Selected collections of the national system have been designated by the IBPGR as part of its international network of base collections (Table 2-9). These may be exchanged as a part of the international collaboration between the NPGS and IBPGR. Many of these collections existed before the IBPGR designation.

The NSSL provides back-up storage for some major international

a popular ornamental in the United States. Creech was attracted to this particular relative of the horticultural plant by what he described as cinnamon-colored bark, which peeled away from the trunk. But its most important characteristic was its later-discovered genetic resistance to powdery mildew (Erysiphe lagerstroemiae), a disease which disfigures the leaves and flowers of infected cultivated plants, particularly in the humid south.

Seed of L. fauriei brought back by Creech was assigned a plant introduction number and initially grown at the Plant Introduction Station, Glenn Dale, Maryland. From there seedlings were widely distributed to botanical gardens and arboreta in the United States, including the National Arboretum in Washington, D.C., where it was tested for susceptibility to powdery mildew and found to be resistant.

Dr. Donald Egolf, a research horticulturist at the National Arboretum, crossed L. fauriei with the common crapemyrtle to produce mildewresistant hybrids. These new hybrids, some of which display novel flower colors, are rapidly replacing the older common crapemyrtle.

Meanwhile, the cinnamon-colored bark that originally attracted Dr. Creech to L. fauriei has made it a desirable ornamental in its own right. Trees can now be found at many botanical gardens and arboreta in the South. Ironically, in its native habitat the tree is threatened by intensive forestry and cutting for charcoal.

“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 John L. Creech, U.S. Department of Agriculture (retired).

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

TABLE 2-8 Back-up Storage at the National Seed Storage Laboratory (NSSL)

Site/Collection

Total Accessions

Number Held by NSSL

Percentage of Total Accessions

Site

     

Ames, Iowa

29,732

8,833

30

Geneva, New York

15,451

8,243

53

Griffin, Georgia

59,290

15,993

27

Pullman, Washington

40,834

23,625

58

Collection

     

Clover

271

189

70

Cotton

4,949

2,248

45

Flax

2,659

2,378

89

National Small Grains Collectiona

114,480

77,927

68

Soybean

12,807

10,776

84

Tobacco

1,272

667

52

a A small sample of every accession in the National Small Grains Collection (NSGC) was sent to the NSSL when the collection was moved from Beltsville, Maryland, to Aberdeen, Idaho, in 1989. These were not of sufficient size to constitute back-up samples and additional seed is being produced. All barley and oats from the NSGC are also backed up at the Canadian National Gene Bank, Ottawa, Ontario.

SOURCE: Data supplied by theDatabase Management Unit, Germplasm Services Laboratory, November30, 1989.

collections. For example, it holds accessions of rice from the International Rice Research Institute (National Research Council, 1988), but these are not inventoried as part of the NPGS collection. The seed accessions are maintained in bond, under quarantine in their original shipping cartons. Their disposition is at the discretion of the originating institution. The NPGS deposits duplicates of its barley and oat collections with the National Plant Gene Conservation Center in Ottawa, Canada, and is seeking arrangements with other nations to hold backups of other collections (H. L. Shands, U.S. Department of Agriculture, personal communication, September 1989).

As part of its comprehensive seed storage function, the NSSL periodically tests seeds to ensure continued viability. Regional stations, curators, and other cooperators are expected to regenerate supplies of seed as requested by the NSSL, although additional funds are not provided for this purpose. The NSSL does not regenerate, evaluate,

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

Back-up accessions of the collection of the International Rice Research Institute are kept in subfreezing storage at the National Seed Storage Laboratory.

enhance, or distribute germplasm as part of its mandate. The laboratory has begun efforts to rescue valuable seed samples of low viability. At present there are no effective plans for regenerating certain seed collections held at NSSL that are unadapted to conditions anywhere in the continental United States or Puerto Rico, even though the NPGS has accepted international base collection responsibility for such collections. This underscores the need for additional facilities and the importance of cooperating with other countries in the regeneration of such germplasm.

The present buildings of the NSSL were completed in the late 1950s and are still structurally sound. However, technological advances in seed storage and the need for more storage space have made the construction of a new, enlarged, and modernized laboratory imperative. Recommendations for the design of an expanded NSSL facility are given in a separate committee report (National Research Council, 1988). Until such facilities are completed, space will continue to be a major constraint on NSSL activities.

Vegetatively Propagated Germplasm

Germplasm held by the national clonal germplasm repositories and the IR-1 is not often stored in base collections as seed. In general, there

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

TABLE 2-9 Collections of the National Plant Germplasm System Designated by the International Board for Plant Genetic Resources (IBPGR) as International Base Collections

Collection

IBPGR-Designated Scope

Maize

New world

Millets (Pennisetum)

Global

Rice

Regional

Sorghum

Global

Wheat

Global

Beans (Phaseolus, cultivated species)

Global

Soybean

Global

Vigna (Vigna unguiculata)

Global

Sweet potato

Global

Allium

Global

Amaranthus

Global

Okra

Global

Tomato

Global

Cucurbits (Cucumis, Citrullus, Cucurbita)

Global

Eggplant

Global

Sugarcane

Global

Forage legumes (Leucaena, Zornia)

Global

Forage grasses (Cynodon, Pennisetum, Paspalum)

Global

SOURCE: International Board for Plant Genetic Resources. 1989. Annual Report 1988. Rome, Italy: International Board for Plant Genetic Resources.

are no back-up or base collections of clonally propagated species, although clonal repositories typically maintain duplicates of field-grown accessions in screenhouses or greenhouses. For some species, seed storage is possible and some of these are held as part of the NSSL base collections. However, seeds from a heterozygous, clonally propagated plant, while preserving the genes of the accession, do not preserve the specific gene combinations that determine the plant's precise characteristics. It may be desirable to conserve selected gene combinations for some species, such as those that require several years to reach maturity.

For materials that must be maintained as clones, the active collections

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

Pineapple germplasm at the National Clonal Germplasm Repository, Hilo, Hawaii, is maintained (A) in the field and (B) as in vitro laboratory cultures. Credit: U.S. Department of Agriculture, National Clonal Germplasm Repository, Hilo, Hawaii.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

usually keep back-up samples as field plantings or in screenhouses or greenhouses. Back-up accessions also may be held as in vitro tissues, plantlets, or other propagative material (e.g., budwood) held in a quiescent state, under special conditions. These back-up holdings are not regarded as base collections because their storage is neither long term nor secure from environmental loss (particularly for field-maintained duplicates). However, they provide some security against complete loss of the primary active collection. As tissue culture and cryopreservation become more reliable as preservation methods, it may be possible to provide back-up holdings of clonal materials at sites separate from the active collection. For example, the NSSL maintains a set of cryopreserved strawberry cultures as an experimental backup to the field collection at the repository in Corvallis, Oregon.

MANAGEMENT

Germplasm management must ensure the continued high viability of all accessions and prompt, accurate distribution of samples in response to requests. Information about accessions, including passport, characterization, and evaluation data, must be in an accessible form to enable users to select from a large array of materials. This is accomplished in the national system through the cooperation of several sites, and it is facilitated by the GRIN database. The elements of this cooperation include the testing of seed viability, increase (regeneration) of seed and clonal germplasm, and distribution.

Seed Viability Testing

Germplasm maintained as seed must be tested regularly to monitor viability. This is carried out by the responsible NPGS site or in cooperation with the NSSL.

Seed germination tests under controlled conditions are performed at intervals that vary with the physiology of the species. Lettuce (Lactuca) and onion (Allium), for example, are more short-lived than many cereal grains or beans and need more frequent testing. Chemical tests of seed viability are less reliable and not generally practiced at NSSL; there is no reliable technique for the nondestructive assessment of viability.

Accessions received with low seed viability pose several difficulties, in part because seed with low viability may not survive well under storage (Priestley, 1986). If the sample size is small, prompt and careful regeneration must be performed to avoid further loss of genetic diversity.

The NSSL and IBPGR standards for viability at one time were different.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

Seed is packaged and sealed in foil-laminated moisture-proof bags for storage at the National Seed Storage Laboratory. Credit: U.S. Department of Agriculture, Agricultural Research Service.

IBPGR set a standard of 85 percent germinability for seed, while the NSSL's minimum standard was 60 percent, but it was recently raised to match IBPGR. For a few accessions, such as some chromosomally aberrant genetic stocks, a lower standard may be appropriate because of their inherently low seed viability, even in freshly grown seed. Current viability data from the NSSL are based on a germination rate of 65 percent. Table 2-10 shows that 164,603 accessions (71 percent) in the collection have a germination rate greater than 65 percent. However, 45 percent of the accessions contain less than 550 seeds.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

TABLE 2-10 Germination Rate and Number of Seeds for Accessions at the National Seed Storage Laboratory (NSSL)

 

Germination Rate Per Accession

   

Total Number of Seed in Accession

>65 Percent

<65 Percent

Unknown

Total Accessions

Percentage of All Accessions

More than 550 seeds

114,534

13,558

128,092

55

Less than 550 seeds

50,069

5,042

49,007

104,118

45

Total

164,603

18,600

49,007

232,210

 

Percentage

71

8

21

   

SOURCE: S. Eberhart, NSSL, personal communication, February 8, 1990. Data are based on germination tests conducted between 1979 and 1989.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

More important than viability, however, is whether the aged seed survives as a consequence of the genes it possesses. Over time selection may favor the survival of particular genotypes. Clearly, viability testing, sampling, and rejuvenation policies and procedures are critical to maintaining the integrity of accessions.

Regeneration and Multiplication

Viability tests, seed distribution, and the decline of viability in storage all reduce the numbers of viable seeds of an accession. New accessions with few or poorly viable seeds require immediate increase. Increase may be necessary when a large amount of seed is needed for special evaluations. Seed regeneration or increase is normally the responsibility of those holding active collections, such as the regional stations, but it may be requested either from the scientist who contributed the materials

Germplasm accessions of chickpea, lentils, and broad bean are grown to produce fresh seed at the Western Regional Plant Introduction Station. Credit: U.S. Department of Agriculture, Western Regional Plant Introduction Station, Pullman, Washington.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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-

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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,

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×

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.

Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 43
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 44
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 45
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 46
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 47
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 48
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 49
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 50
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 51
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 52
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 53
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 54
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 55
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 56
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 57
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 58
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 59
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 60
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 61
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 62
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 63
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 64
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 65
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 66
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 67
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 68
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 69
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 70
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 71
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 72
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 73
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 74
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 75
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 76
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 77
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 78
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 79
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 80
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 81
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 82
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 83
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 84
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 85
Suggested Citation:"2 Elements of the National Plant Germplasm System." National Research Council. 1991. The U.S. National Plant Germplasm System. Washington, DC: The National Academies Press. doi: 10.17226/1583.
×
Page 86
Next: 3 Administration of the National System »
The U.S. National Plant Germplasm System Get This Book
×
Buy Hardback | $50.00
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

In the United States, the critical task of preserving our plant genetic resources is the responsibility of the National Plant Germplasm System (NPGS).

NPGS undergoes a thorough analysis in this book, which offers wide-ranging recommendations for equipping the agency to better meet U.S. needs—and lead international conservation efforts.

The book outlines the importance and status of plant genetic conservation and evaluates NPGS's multifaceted operations. Two options for revamping NPGS within the U.S. Department of Agriculture are included.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!