The U.S. National Plant Germplasm System (1991) / Chapter Skim
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1 Managing Crop Genetic Resources
1 Managing Crop Genetic Resources
Pages 21-42
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From page 21... ...
Over the years, the reasons for assembling collections of crop germplasm have become more compelling. They now include concern over loss of biological diversity as well as the economic importance of accessibility to the germplasm resources needed to sustain national food supplies.
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From page 22... ...
Thus, seed of an old, heirloom tomato variety is just seed when produced by a gardener or seed company, but it is germplasm when part of a collection gathered to conserve the genetic diversity of tomatoes or to develop a breeding program for new tomato varieties, or even for the purpose of preserving particular genetically controlled traits. Today's scientists and crop breeders must have access to, and knowledge of, a wide array of crop varieties, landraces, and related wild species in their search for specific genetic traits.
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From page 23... ...
Obsolete varieties are also found in the collections of individuals and organizations that preserve the seeds of "heirloom" varieties. Primitive landraces, indigenous varieties, and specifically adapted ecotypes are important genetic resources.
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From page 24... ...
Genetic stock collections are often difficult and expensive to maintain, and specialized knowledge, skills, and facilities are required to increase and maintain accessions. Special germplasm collections accumulated through genetic and breeding research have been the basis for studies of speciation, evolution, or taxonomy; manipulations of genes, chromosomes, or entire genomes; and the incorporation of genes into crop plants from weedy relatives or related species.
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From page 25... ...
However, its general application to germplasm management and crop improvement will require considerably greater knowledge of gene structure, regulation, placement, and function than currently exists as well as more precise understanding of the genetic control process of important crop traits. Larger human populations, widespread use of new high-yielding varieties, and agricultural development projects focus concern on the collection, maintenance, and evaluation of genetic resources that are disappearing from farmers' fields and their native environments.
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From page 26... ...
Seventeenth century French explorers described the plant as folle avoine, wild oats, to which it bears closer resemblance than to cultivated rice. It was not until the early twentieth century that wild rice appeared in markets.
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From page 27... ...
Regeneration, characterization, evaluation, and documentation are important parts of the activity of managing genetic resources that must be addressed by a program. The breakthrough that allowed farmers to grow wild rice came somewhat unexpectedly from a routine inspection of a field in Waskish, Minnesota, in 1963.
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From page 28... ...
of accessions of a species or crop. This will usually involve special screening tests designed to measure disease and insect resistance, tolerance to various field environments, replicated yield trials, or even yield evaluations of many stocks hybridized by an elite, adapted tester as the common other parent.
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From page 29... ...
Knowledge of existing collections and information about the genetic diversity of the crops in general help in setting exploration priorities. The aim of acquisition is to obtain the most genetically diverse collection possible of the crop and its useful relatives (Simmonds, 1979~.
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Tissue culture, in vitro storage, cryopreservation, and pollen storage provide alternatives for medium-term and long-term maintenance. Special sites or facilities are used for these purposes.
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An emphasis that includes a wider range of wild species related to crops may also increase the size of collections. Further, new technologies for gene transfer hold the promise that plant breeders may be able to move genes freely among distantly related species.
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In the United States, germplasm efforts must be organized as part of the emerging global system. Priorities and goals should reflect the responsibilities of participating in an international cooperative effort to manage plant genetic resources.
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number above represent information contained in the Germplasm Resources Information Network (GRIN)
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From page 34... ...
Plants used in breeding modern crop varieties often include related wild species. Most of the genes for pest and disease resistance in tomatoes come from wild Lycopersicon species.
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From page 35... ...
(National Research Council, 1972; Plucknett and Smith, 1982~. Importance to Society and the Environment Genetic resources can be lost or diminished through habitat destruction, displacement by other species, natural disasters, and neglect.
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sugarcane 1980 1981 1982 1983 cc 80m ~ _~V ~ 1920 1930 1940 1950 1960 1970 1980 YEAR FIGURE 1-2 Commercial cultivars are often replaced with newly developed ones that have better production qualities, yields, or resistance to pests or pathogens, as illustrated in (A) winter wheat and (B)
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From page 37... ...
The conservation of the broad range of plant genetic diversity, even when narrowed to agricultural concerns, is beyond the capacity of individuals, private companies, or small groups, although each of these can and does contribute to managing genetic resources. It requires the cooperation of a broad range of scientists, policymakers, administrators, and other concerned individuals.
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~ ~ .~ do- ~ ~ T Development of Germplasm Activities in Me United States Efforts to gather genetic resources began in the early days of the Republic when various officials of the U.~.
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From page 39... ...
"GRIN Data" for the plant introduction (Pl) number above represent information contained in the Germplasm Resources Information Network (GRIN)
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From page 40... ...
In the summer of 1946 the 79th Congress passed Public Law 733; Title II of which is the Agricultural Marketing Act of 1946. This act provided the legal basis for establishing state-federal cooperation in managing crop and livestock genetic resources, and included an amendment to the earlier Bankhead-Iones Act of 1935 to support research (Title I)
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From page 41... ...
Following congressional passage of the Agricultural Marketing Act of 1946, action was taken to establish a cooperative enterprise that was coordinated through the newly designated Plant Introduction Section of the Agricultural Research Service (ARS)
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From page 42... ...
Many early breeders' lines would also have been lost unless conserved in collections, such as those of the NPGS. The NPGS is the world's largest distributor of plant germplasm.
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