W_OLD006: Plant Genetic Research Conservation and Utilization
Statement of Issues and Justification
In response to the negative impacts of biotic and abiotic variables on crop production, a broad genetic base is critical for U. S. agriculture in the development of new cultivars or the improvement of existing ones. The wide array of plant genetic resources (germplasm) that are maintained as part of the W-6 Regional Research Project, also known as the Western Regional Plant Introduction Station (WRPIS), provide stakeholders the genetic materials to achieve crop development. For W-6 these resources include forage and turf grasses, beans, cool season food legumes (pea, lentil, chickpea, fava bean, lupine, etc.), lettuce, safflower, onion relatives, and forage legume crop species to name just a few. Other important taxa relate to new crops, ornamental species, and medicinal plants. Availability of this germplasm is critical to researchers in the Western Region who represent both public and private sectors. Ready availability of the most diverse collections of these genes is best maintained through the existing infrastructure of the USDA, ARS, National Plant Germplasm System (NPGS) and the close association with the other germplasm related Regional Research Projects, which include the North Central (NC-7), Northeastern (NE-9) and Southern (S-9), as well as the other 22 special clonal and seed germplasm repositories. These genetic resources are readily recognized as important and crucial in the agricultural production system as water, air, soil, and minerals.The conservation and utilization of these genetic resources ultimately affect our quality of life. This project safeguards and promotes utilization of a wide array of plant genetic resources for grower, processor and consumer stakeholders. This project, one of the four initial Regional Plant Introduction Stations established in the 1950s, is a vital component of the USDA, NPGS. The WRPIS is responsible for 15.4% of the total accessions and 23.5% of the total taxa in the NPGS. The size of the collection has grown from 53,000 accessions to over 70,000 accessions in the past ten years (Attachment: Growth in WRPIS Germplasm Collections). Project research, information documentation and germplasm conservation relate directly to all aspects of the USDA, ARS National Program Action Plan.
Specifically, the use of plant germplasm by researchers in the Western Region, particularly scientists associated with the SAES Universities, is significant. Plant germplasm is utilized in the region to support crop development, help to sustain small farm agriculture, preserve endangered species, and even repatriate crops to centers of diversity. It is also used to develop new U.S. crops, and encourage international trading diplomacy through exchange of plant germplasm. Over the past seven years public and private sector plant researchers from the Western Region request approximately 26% of the germplasm distributed by the whole NPGS, and ranges between around 26,000 to over 61,000 accessions per year (Attachment: Germplasm Use in the Western Region, Table 1.). Of this material, W-6 directly provides 5,000 to 7,000 accessions each year (Attachment: Germplasm Use in the Western Region, Table 2.) to researchers in the Western Region.
Much of the literature dealing with germplasm conservation and evaluation is specific (23,51,52,56), indicating that each crop must be tested before general rules for maintenance, preservation, and evaluation can be applied. There are, however, some general rules that are effective in germplasm management. Marshall and Brown (40), argue that relatively common alleles merit priority during regeneration. They point out that for sample size stored in collections, and for sample size distributed, the objective should be to assure (0.95 probability) that at least one copy of each allele occurring at a frequency of >0.05 is obtained and maintained. To meet this requirement quantitative genetic analysis and statistical predictions are used to determine regeneration populations based primarily on the pollination biology of the respective species. Theoretical population sizes, however, must sometimes be modified to a lesser number of plants due to practical concerns and functional realities. This may present the risk of losing alleles at very low frequencies, but is the best compromise when considering the limitations of resources at the WRPIS. Regeneration protocols for any given taxa are under constant refinement. There are few published guidelines on the regeneration of the wild relatives of crop species (33,41), and none for many of the "new crop" species.
Use of molecular techniques in germplasm management has provided a more exacting way of comparing genetic diversity in various aspects of the maintenance and evaluation programs. The advantages and disadvantages of such methods were covered in detail by Bretting and Widrlechner (3). They stressed that genetic marker data should be considered a complement to, not a replacement of, managerial experience with germplasm. The use of molecular techniques in the development of core subsets is well described (3,4,37). Utilization of these cores, especially in large collections, continues to be examined to evaluate its utility in improving the efficiency of germplasm management (24,29,62,67).
The WRPIS research on disease and insect resistance has been an important part of the evaluation program in the past (8-13,31,32,35,38,49). This type of research will be continued to better characterize important traits of use to breeders and geneticists.
Biotic pressures and stresses (i.e. insect and disease) encountered in the course of germplasm maintenance efforts play critical roles in the ultimate success of the NPGS, and particularly the WRPIS, to provide the best quality and ample distribution quantity of germplasm accessions. Sound hypothesis testing research, conducted to assess etiologies of diseases and positive or negative interactions between arthropods and hosts, is critical to the success of the overall mission of the management unit.
The range of plant taxa (over 2,400 species) maintained at the WRPIS includes almost the entire spectrum of pollination biologies found in the plant kingdom. Understanding the specificity and mechanics of the various pollination systems with which we are confronted is critical to the success of conservation of plant biodiversity. Similarly, understanding the relationships between insect vectors and the potential array of plant pathogens (viral, bacterial, fungal) or endophytes or beneficial microbes that can infect germplasm increase plots is essential to the efficient and economic maintenance of the collections.
Adequate characterization of each germplasm accession and subsequent documentation of those data into the GRIN database will provide the necessary information to the germplasm user community to efficiently utilize the wide range of genes available. This necessarily entails the inception of or development of plant character descriptors that is a standard among U.S., or even international, plant scientists.
Molecular characterization of accessions in any given plant germplasm collection will provide an additional and valuable tool for collection management. These data will be important in both measuring genetic diversity among accessions, as well as help to identify duplicates within the collections. Research, and the subsequent information generated, will facilitate the identification of universal marker sets for future characterizations of new accessions added to the collections, for gene mapping activities, and construction of consensus diversity tables.
Because of the diversity of environments and needs in the Western Region, and the diversity of research interests and expertise available, it is both efficient and economical that a multi-disciplinary effort continue to evolve in order to utilize the talents of all interested researchers in the region. It is also critical that these valuable germplasm resources be made available, kept in superior quality condition and subsequently provided expeditiously to researchers.
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