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Report
on the Status of
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Prepared by
Developed and Edited by
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Table of Contents Chapter 1 - The Genus Medicago
Chapter 2 - Genetic Vulnerability in Alfalfa
Chapter 3 - Alfalfa Breeding Introduction
Chapter 4. National Plant Germplasm System Medicago Germplasm Collection
Appendix 1. Taxonomic listing of Medicago species, geographic distribution, number of accessions, and conservation status Appendix 2. Evaluation status of the perennial species Appendix 3. Evaluation status of the annual species Appendix 4. Germplasm enhancement proposal for development of national and regional germplasm pools References Compilation of Recommendations List of Tables
Table 1. List of cultivated Medicago species their common name, usage and growth cycle Table 2. Alfalfa and All-Hay production by states in 1998 Table 3. List of Institutions and locations were germplasm research is taking place Table 4. Alfalfa germplasm collection trips made by U.S. scientists in the last 100 years Table 5. Number of accessions in the primary gene pool and their country of origin Table 6. List of wild relatives of alfalfa by category List of Figures Figure 1. All hay production (Acres & Production) 1865-1998 Figure 2. Alfalfa hay production (Acres & Production) 1940 - 1998 Figure 3. Germplasm sources us in alfalfa cultivars (All dormancy classes) 1986 - 1999 Figure 4. Germplasm sources us in alfalfa cultivars (Dormant) 1986 - 1999 Figure 5. Germplasm sources us in alfalfa cultivars (Non-dormant) 1986 - 1999 Figure 6. World distribution of landrace germplasm Figure 7. World distribution of cultivated germplasm Figure 8. World distribution of wild Medicago sativa subsp. sativa germplasm Figure 9. Number of seed requests (1993 to 1995) |
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Summary Status of the Medicago Germplasm in the United States Medicago Germplasm in the United States Production Trends and Value of Alfalfa Alfalfa acreage is at 23.6 million acres and is predicted to maintain or drop slightly in acreage primarily due to the increase productivity of each acre. Alfalfa is the best animal feed for ruminant livestock and horses and it ranks 4th among all U.S. agricultural crops grown with an annual production value of $8.1 billion . When the value of animal products is added to the value of alfalfa hay, the dollar value of alfalfa reaches $145 billion annually. Thus far exceeding the combined value of all other high value crops. Annual medics do have potential uses in sustainable agriculture systems, however, additional research is needed to discover their niche in the U.S. Crop Vulnerability The general impression has been that crop genetic vulnerability was not a large concern due to the autotetraploid nature of Medicago sativa subsp. sativa, the high level of outcrossing, and the diversity of germplasm sources utilized in the development of alfalfa cultivars. However, a survey of the cultivars released over the past 14 years has shown a narrowing of the germplasm utilized. Germplasm Activities Development of alfalfa cultivars has shifted from the public sector to private companies over the past 60 years. Today, virtually all commercial alfalfa cultivars are developed by private companies. The USDA-ARS breeding effort has shifted towards germplasm collection, evaluation, enhancement and development as well as fundamental classical and molecular studies on alfalfa and related species. The University's have also shifted towards germplasm evaluation, enhancement and development, however, a few public breeders continue to develop special use cultivars of alfalfa. The University's have also been involved in fundamental studies of alfalfa particularly in the area of molecular biology. Who's Involved? Organizations involved in germplasm development include federal, state, and private companies. The North American Alfalfa Improvement Conference continues to be the conduit through which scientific information is exchanged between public organizations and private companies for the benefit of the alfalfa crop. Overview Summary of Recommendations Prioritized recommendations
1. Seed Regeneration Although the seed regeneration of almost all the collection has been completed, the need remains to increase accessions that are low in number, have low viability, and new accessions coming into the collection. Without the continued vigilance in maintaining our current collection, future collections, evaluations and enhancements would be of little value. 2. Germplasm collection The greatest needs for the collection are for the wild perennial species in the secondary and tertiary germplasm pools, especially those species which are considered threatened. Countries where future collections should occur include the Georgia, Crimea and Southern Caucasus mountain regions of the former Soviet Union, the Himalayan region of India, south and north east regions of China, Sudan, Egypt and the Arabian Peninsula, South Africa, Northern Kazakhstan, and adjacent Central Asian countries (i.e. Kyrgistan, Uzbekistan, Afghanistan), Iran and Iraq. 3. Germplasm Evaluation A set of descriptors for all accessions, especially all alfalfa accessions needs to be completed. The currently established core subsets should be reevaluated once descriptor data has been obtained on the entire collection. Accession classification based on molecular markers needs to be accomplished and molecular data compared to classifications based on morphological and ecogeographic descriptors. In addition, evaluations which can broaden the use of alfalfa need to be carried out. 4. Germplasm Enhancement National and regional germplasm pools should be developed. A Compilation of the Specific Recommendations is Located on Page 50. Alfalfa Crop Germplasm Committee Report Status of the Medicago Germplasm in the United States |
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Chapter 1 - The Genus Medicago Introduction The genus Medicago is a member of the Legume family. According to Small and Jompe (1989) the genus contains 30 perennial species and 60 annual species (Appendix 1). About 15 species are cultivated for various uses (Table 1.):
Alfalfa (Medicago sativa L. sensu lato) is a perennial species and the most important forage legume in North America. The annual species, referred to as medics, serve as important components in pastures in regions with Mediterranean climates. Table 1. List of cultivated Medicago species their common name, usage and growth cycle.
Alfalfa Alfalfa, called the "Queen of the Forages," is the fourth most widely grown crop in the United States. Alfalfa hay is used primarily as animal feed for dairy cows but also for horses, beef cattle, sheep, chickens, turkeys and other farm animals. Alfalfa is recognized as one of the most important crops to U.S. agriculture due to its ability to:
In addition to the traditional uses of alfalfa as an animal feed, alfalfa is beginning to be used as a bio-fuel for the production of electricity, bioremediation of soils with high levels of nitrogen, and as a plant factory for the production of industrial enzymes such as peroxidase, alpha-amylase, cellulase, and phytase. Alfalfa is also consumed directly by humans as alfalfa sprouts and alfalfa juice is found in some health food products. Plant molecular biologist use alfalfa as a model crop due to it ability to grow entire plants from single cells and it's ability to be genetically transformed thus allowing improvements of the crop through gene insertion. Production Alfalfa is grown in all 50 states over a wide range of climatic conditions from fall dormant types in the Midwest and Northeast where winter survival is key, and non-dormant types in the Southwest U.S. where extensive growth is needed from October to March. There are 23.6 million acres of alfalfa cut for hay with an average yield of 3.5 tons per acre. Alfalfa is sometimes grown in mixtures with forage grasses and other legumes. Since the introduction of alfalfa into the U.S. the productivity of forages has dramatically increased (Figure 1). The acreage of all hay harvested including alfalfa is 60.8 million per year. The production of alfalfa hay on a large scale began around 1919 in the U.S. and has grown from 14 million acres in 1940 to it's highest number of acres of nearly 30 million acres in 1965. Since 1965 the total number of acres of alfalfa has decreased slightly, however, the productivity of alfalfa fields has been steadily increasing (Figure 2). Over the past 10 years the total number of acres has decreased from 26.7 million acres in 1987 to 23.6 million acres in 1997, however, the production has increased from 2.59 tons per acre with a total of 69.3 million tons to 3.47 tons per acre with a total of 82 million tons. The increased productivity of alfalfa over the years can be attributed to better management practices, genetic improvement of cultivars, and the increased use of mechanization for harvesting alfalfa. Table 2. Alfalfa and All-Hay production by states in 19981.
1 Statistics obtained from the 1998 USDA - National Agricultural Statistics Service. |
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Figure 1.
Figure 2. |
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Highlights of Alfalfa Production (Barnes, et. al, 1988)
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Value Alfalfa is primarily grown on the farm in which it is consumed, thus it is difficult to estimate the actual value of alfalfa. Alfalfa hay is used primarily as animal feed with an estimated value of $ 8.1 billion. Alfalfa is also grown in mixtures with forage grasses and other legumes. The estimated value of all hay is $13.4 billion. The average cost of alfalfa hay is $102.50 per ton. Alfalfa meal and cubes are exported to other countries with a value of $49.4 million to the U.S. economy When the value of animal products estimated at $132 billion from products such as milk, cheese, butter, meat, wool, etc. is added to the value of hay, the value of alfalfa reaches the $145 billion level. This far exceeds the combined value of all other high value crops. Alfalfa seed is primarily grown in the western areas of the U.S. primarily in the states of California, Idaho, Nevada, Oregon, Wyoming, and Washington. The total U.S. production of alfalfa seed in 1999 was 115 million pounds, with an average price of $190 per 100 pounds of seed. Thus, the estimated value of alfalfa seed in the U.S. is $218.5 million. A fringe benefit to the production of alfalfa seed is the production of honey from bees. In the U.S., $147.7 million dollars worth of honey is produced each year. Alfalfa is also directly consumed by humans in the form of alfalfa sprouts. According to the International Sprout Growers there are approximately $250 million dollars worth of sprouts sold annually in North America. Alfalfa juice is used in some health food products with an undefined economic value. Annual Medics Annual Medicago species, referred to as medics, are excellent candidates for use in sustainable agriculture systems such as pastures and cover crops. Medics are native to semiarid areas around the Mediterranean Sea and have long been used in unimproved pastures in the region. Medics are now widely distributed throughout the world, largely in areas with mild, rainy winters and alkaline soils. Medics are among the principal legumes used in the Australian ley farming system, and constitute over 50 million hectares of the Australian agriculture zone (Crawford et al., 1989). Medics have been most successful in cereal-legume crop rotation systems in southern Australia where winter rainfall averages between 250 and 500 mm. The species most widely grown in Australia are: M. littoralis Rohde ex Lois., M. polymorpha L., M. rugosa Desr., M. scutellata (L.) Miller, M. italica (Miller) Fiori, and M. truncatula Gaerth. What are Medics?
Uses of annual medics The agronomic potential of the medics has been investigated and several different systems have been developed. 1) The medics can be used as permanent pasture; 2) mnedics can be used as a green manure crop due to it's ability to fix nitrogen and as a cover crop to prevent soil erosion; 3) annual medics can be used as a companion crop to control weeds, add organic matter, lower soil temperatures and provide fall residue after harvest. Various crops have been utilized including corn, soybeans, small grains, sunflower, squash and some herbs; 4) vineyards and fruit orchards have used annual medics in the alleyways to provide ground cover for soil erosion, an environment for beneficial insects, and a stable track for equipment; and 5) use of annual medics as wildlife habitat for deer, quail and water fowl have been initiated. Medics do have potential uses in sustainable agriculture systems, however, additional research is needed to discover their niche (Bauchan, 1999). Chapter 2. Genetic Vulnerability in Alfalfa Introduction The general impression has been that crop genetic vulnerability was not a large concern due to the autotetraploid nature of Medicago sativa subsp. sativa, the high level outcrossing, and the diversity of germplasm sources utilized in the development of alfalfa cultivars between 1930 and 1977 (Barnes 1977). Two decades have past since this initial assessment was made, it seems prudent to reassess the present day status of the genetic vulnerability in alfalfa. Origins of Alfalfa Cultivars (1850 -1977) Alfalfa originated in Vavilov's "Near Eastern Center"--Asia Minor, Transcaucasia, Iran and Turkistan. In the wild, M. sativa and related perennial species are found throughout Eurasia and as far north as Siberia. Alfalfa spread from its center of origin into Europe, North Africa, Arabia and eventually South America with invading armies, explorers, and missionaries as feed for horses and other livestock. In 1736, European colonists brought alfalfa to the eastern U.S. where the crop was referred to by its European name, lucerne. These introductions generally were not successful, except for a few planted on well-drained limestone soils. Alfalfa was well suited to the dry climates and irrigated soils of the western U.S., where it was introduced from Mexico by Spanish missionaries as early as the 1830s. Alfalfa eventually spread eastward to the Intermountain region and the southern Great Plains. Movement into areas with severe winters was limited by the lack of winter hardiness in the primarily Spanish-derived (non-dormant) germplasm. The introduction of four winter-hardy (dormant) types (cv. Grimm, cv. Ontario Variegated, cv. Baltic, and cv. Cossack) from northern Europe to the North Central States between 1858 to 1910 allowed successful alfalfa culture in the colder and more humid areas of the Midwestern and Northeastern U.S. Before 1925, most alfalfa breeding efforts in North America were directed toward selecting strains that were more winterhardy. During the next 30 years, emphasis was placed on developing cultivars that combined winterhardiness and resistance to bacterial wilt. During the late 1950s, the emphasis was placed on developing cultivars resistant to other diseases and several insect pests (Barnes et al., 1988). Beginning in the 1950's there was an emphasis on breeding alfalfa with multiple pest resistance through recurrent selection breeding schemes. Most modern varieties of commercial alfalfa have moderate to high levels of resistance to the major disease, insect and nematode pests. Scientists belonging to the North American Alfalfa Improvement Conference have developed standardized test procedures for screening alfalfa for the following diseases, insects and nematodes. Diseases of Alfalfa
Insects of Alfalfa
Nematodes of Alfalfa
Alfalfa Genetic Vulnerability In assessing the genetic vulnerability of alfalfa in 1977, Barnes credited nine distinct germplasm sources which were introduced into the U.S. from different regions of the world, in the development of modern alfalfa varieties. They are described in descending order from the most winter hardy (most fall dormant) to the least winter hardy (least fall dormant): 'Falcata', 'Varia', 'Turkistan', 'Flemish', 'Chilean', 'Peruvian', 'Indian", and 'African' (Barnes et al. 1977). The 1977 report concluded that a trend toward increased genetic diversity in alfalfa cultivars, spurred largely by breeding efforts begun in the 1950s, and the inherent genetic heterogeneity of the species had made alfalfa less vulnerable to catastrophic loss than it was prior to the 1950's. However, the report also stated that "the broad use of the recognized germplasm in most varieties is cause for concern about future yield improvements" (Barnes 1977). Current Status of Alfalfa Genetic Vulnerability (1985-2000) Over the past 15 years (1985-2000) a majority (76%) of the cultivars released have been fall dormant type alfalfas. There are three germplasm sources that have been used extensively, Flemish (31%), Varia (17%) and Turkistan (11%) (Figure 3). Within the dormant alfalfas, most of the selections have been made from two germplasm sources, Flemish (39%) and Varia (21%) (Figure 4). Whereas, within the non-dormant types of alfalfa most of the selections have been made from three germplasm sources, African (34%), Indian (17%), and Turkistan (14%) (Figure 5). Research begun in the 1980's increased the use of plant introductions which were wild perennial relatives of alfalfa. Three perennial species, M. glandulosa, M. glutinosa, and M. prostrata are recognized as the sources of glandular hairs which have been transferred to alfalfa to provide tolerance to the potato leafhopper. Recommendations: There is a need to broaden the germplasm base used in alfalfa cultivars
released by the alfalfa seed industry. The introduction of wild perennial
germplasm and very non-dormant types from the Saudi Arabian Peninsula are
examples of the beneficial attributes available.
Figure 3.
Figure 4.
Figure 5. 1997 List of Threatened Alfalfa Relatives and Other Medicago Species The following Medicago species have been listed by the World Conservation Monitoring Center as having a world status of vulnerable or rare:
* Note that this list includes three species considered to be wild relatives of cultivated alfalfa. |
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Chapter 3 Alfalfa Breeding Introduction The first breeding efforts in the U.S. date back to the 1850's for non-dormant alfalfas and the early 1900's for dormant types of alfalfa. Most alfalfas grown in the early years were selections of the best materials imported from Europe and Russia. In the Midwest in the early 1900's the emphasis was the selection for winter hardiness. From alfalfa's initial introduction until 1955, about 33 recognized alfalfa cultivars or regional strains were grown in the U.S. and Canada. About half of these were directly introduced from Europe, Asia or the Near East. Between 1958 and 2000, organized alfalfa breeding expanded tremendously and the number of recognized cultivars increased to about 400. From the 1900's until the 1950's almost all of the new alfalfa cultivars were developed by the USDA and public university programs. The goal of these programs was primarily to increase winter hardiness and the development of bacterial wilt resistance. Starting in the 1950's the alfalfa seed industry began. Since their inception, private alfalfa breeding programs in the U.S. have been responsible for the rapid increase in numbers of recognized alfalfa cultivars. During the period between 1955 and 1960, approximately 20% of cultivars were released from private breeding programs. This proportion increased to more than 95% between 1985 and 1990 and nearly 100% between 1990 and 2000. Private breeding programs increased in number, size and sophistication from about 1965 to 1985. During the late 1980s, competition for market share caused several mergers within the private sector. At present, there are about 8 commercial alfalfa breeding programs with annual research expenditures ranging from nearly $100,000 with 1.0 scientist-year (SY) to more than $2 million with five or more SYs. The rate of release of new alfalfa cultivars in the U.S. has increased steadily over the last 90 years. About one cultivar was released every three years between 1901 and 1940; one each year between 1941 and 1960; about 17 per year between 1981 and 1985; about 30 each year between 1985 and 1990; about 60 per year between 1990 and 1995, and about 100 per year between 1996 and 2000. Increased breeding by industry was accompanied by a reduction in the number of public breeding programs, and by a change in the direction of public research from breeding new cultivars to developing new breeding procedures and improved germplasm (Barnes et al., 1988). The transition from applied alfalfa breeding to more fundamental research within public agencies contributed to the development of several comprehensive research efforts. Examples of research areas include:
More generally, public researchers working with alfalfa also continue to provide valuable knowledge in plant genetics, physiology, and growth, including resistance to biotic and abiotic stresses. Public research in cooperation with industry partners has lead the way in developing potentially new uses of alfalfa for a bio-fuel for the production of electricity, bioremediation of soils with high levels of nitrogen, and as a factory for the production in bioreactors of industrial enzymes. In discussing research directions for the 1990s and beyond, the Alfalfa Crop Germplasm Committee (ACGC) listed the following as new uses or value-added traits that could be developed in alfalfa (Minutes of the Alfalfa CGC, October 9-10, 1990, Kansas City, MO):
The increased commitment to alfalfa improvement in the private sector has been associated with a concomitant decline in the number of public alfalfa researchers. The wide acceptance of the best proprietary cultivars by the 1980s confirms the efficacy of private breeding programs, and suggests that an appropriate balance has been reached between fundamental public research and more applied private research. However, the balance between public and private programs may now be in danger because of reductions in support for public alfalfa research programs. The termination of a number of public alfalfa breeding and genetics programs also means that many breeder's germplasm collections may be subject to loss. Alfalfa Crop Germplasm Committee (ACAC) The Alfalfa Crop Germplasm Committee consists of 21 members representing federal, state and private interests. There are representatives of several scientific disciplines including: breeding, genetics, cytogenetics, entomology, pathology, physiology, microbiology, and molecular biology. In addition there is geographic representation of breeders from the major alfalfa growing areas of the U.S. The Alfalfa Crop Germplasm Committee address escritical issues facing the National Plant Germplasm System (NPGS) especially related to the genus Medicago. These include:
Formation The Alfalfa Improvement Conference (now the North American Alfalfa Improvement Conference - NAAIC) has since it's inception in 1934 been concerned with alfalfa germplasm. In the early days of the conference there was need for germplasm exchange among scientists, seed production of experimental strains in the western U.S., development of a standardized system of note taking, and testing alfalfa cultivars for disease and insect pests, yield, and persistence. Several committees grew out of the Alfalfa Improvement Conference which were related to germplasm, they included: variety testing, release of new cultivars, available breeding lines, lists of cultivar descriptors, development of standardized tests for characterizing pest of alfalfa, and the National Alfalfa Variety Review Board. The Alfalfa Crop Germplasm Committee was formerly organized in 1969 as the Germplasm Committee of the Alfalfa Improvement Conference. Accomplishments of the Alfalfa Crop Germplasm Committee.
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Table 3. List of Institutions and locations where germplasm research is taking place.
| Institution | Location | Agronomic | Physiological | Diseases | Insects | Nematodes | Bio-Tech | Prebreeding | Cultivar Development |
| USDA-ARS | Manhattan, KS | X | X | X | X | X | |||
| USDA-ARS | Beltsville, MD | X | X | X | X | X | |||
| USDA-ARS | St. Paul, MN | X | X | X | X | X | X | ||
| USDA-ARS | Stoneville, MS | X | X | X | |||||
| USDA-ARS | Logan, UT | X | X | X | X | ||||
| USDA-ARS | Prosser, WA | X | X | X | X | X | |||
| University of Arizona | Tucson, AZ | X | X | X | X | ||||
| University of California | Davis, CA | X | X | X | X | ||||
| University of Georgia | Athens, GA | X | X | X | X | X | |||
| Iowa State University | Ames, IA | X | X | X | X | ||||
| Purdue University | West Lafayette, IN | X | X | X | X | ||||
| Kansas State University | Manhattan, KS | X | X | X | |||||
| University of Minnesota | St. Paul, MN | X | |||||||
| New Mexico State University | Las Cruces, NM | X | X | X | |||||
| Cornell University | Ithaca, NY | X | X | X | |||||
| Ohio State University | Columbus, OH | X | |||||||
| Oklahoma State University | Stillwater, OK | X | X | ||||||
| University of Wisconsin | Madison, WI | X | X | X | X | ||||
| University of Wyoming | Laramie, WY | X | X | X | |||||
| ABI Alfalfa | Ames, IA | X | X | X | X | X | X | ||
| Cal/West | Woodland, CA | X | X | X | X | X | X | ||
| Dairyland Seeds | Clinton, WI | X | X | X | X | X | X | ||
| Forage Genetics | West Salem, WI | X | X | X | X | X | X | X | X |
| Great Plains | Apex, NC | X | X | X | X | X | X | ||
| Pioneer Hi-Bred | Johnston, IA | X | X | X | X | X | X | X | X |
| WL Research | Evansville, WI | X | X | X | X | X | X | X |
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Chapter 4. National Plant Germplasm System Medicago Germplasm Collection Introduction The National Plant Germplasm System Collection of Medicago germplasm is currently located at the Western Regional PI Station in Pullman, Washington. Stephanie Greene is the curator of the collection who can be contacted at the USDA-ARS, Washington State University Irrigated Agricultural Research and Extension Center, Prosser, WA 99350 Phone: (509) 786-9265, FAX: (509) 786-930, e-mail: sgreene@ars-grin.gov. The current collection contains a total of 7,554 accessions with 4,108 perennial accessions representing 30 species and 3,446 accessions representing 60 annual species (Appendix 1). History The beginning of the U.S. Medicago germplasm collection traces back to 1898. Accessions were collected directly in the field by plant explorers and scientists or obtained from agricultural institutes, seed companies and U.S. Embassy agricultural attaches. About 65 collection trips that focused on alfalfa germplasm have been made in the last 100 years (Table 4). The majority of accessions that are available today were received after the 1940s. During the 1950s, 60s and 70s the collection grew by an average of 1400 accessions per year. During the eighties, more than 4200 accessions were added to the collection. During the nineties, the collection grew by 1400 accessions. The collection currently contains over 7000 accessions representing 80 species from 94 countries. Table 4. Alfalfa germplasm collection trips made by U.S. scientists in the last 100 years
In the early part of the century, alfalfa germplasm was obtained and selectively distributed by the USDA Office of Foreign Plant Introduction, in Beltsville, Maryland. In the 1940's the Regional Plant Introduction Stations were established to increase, evaluate, and distribute plant introductions. As plant introductions came into the United States, they were distributed to the four Regional PI Stations for evaluation. By 1949 the North Central Regional Plant Introduction Station (NCRPIS) in Ames, Iowa became the main site responsible for the increase, evaluation and distribution of alfalfa plant introductions. In 1971, the USDA National Plant Germplasm System was established, with the broader mission of preserving and encouraging the use of germplasm as a guard against genetic erosion and crop vulnerability. In 1977, NCRPIS set up a specific cooperative agreement with University of Nevada, Reno, to increase the alfalfa accessions under caged conditions. This project was terminated in 1986. In 1987 the alfalfa collection was transferred from Ames, IA to the Western Regional Plant Introduction Station (WPIS), in Pullman, WA. A Specific Cooperative Agreement was set up with Washington State University, Prosser to increase the alfalfa accessions under caged conditions. Efforts in the last two decades have focused on systematically regenerating the entire collection using controlled pollination, since prior seed increases had been contaminated by open pollination. A second important emphasis in the last two decades has been a germplasm evaluation program directed by the ACGC and administered by WRPIS. The objective of the ACGC has been to obtain a set of standard descriptors on newly regenerated material, since previous evaluations had been conducted on accessions representing open pollinated populations. Each year evaluation proposals were reviewed and funded based on priorities determined by the ACGC. By 1988, the USDA alfalfa CRIS project was funded at $160,000. This supported regeneration efforts at Prosser, WA, in the form of supplies and field labor. It also provided support for the germplasm evaluation program managed by the ACGC. In 1993, an alfalfa curator was hired to manage the collection, which had previously been managed by the Research Agronomist, Dr. R.C. Johnson, at the Western Regional PI Station. Whereas the salaries of R.C. Johnson and R. Peaden had not been supported by the Alfalfa CRIS, the alfalfa curator's salary was. In 1995, the Trifolium (5000 accessions) and Lotus (700 accessions) collections were transferred from the Northeastern Regional Plant Introduction Station in Geneva, New York, to WRPIS, in Pullman. The Alfalfa CRIS was rewritten to include the clover and trefoil collections, but no additional funds accompanied the collection transfer. With a flat budget and expanded responsibilities, funds have focused exclusively on regeneration activities. The ACGC-directed germplasm evaluation program was ended in 1997. One of the final projects of the ACGC evaluation program was to develop core subsets of the annual and perennial species. Core Subsets Introduction A core subset is a small subset of accessions from the entire collection that: 1) contains most of the genetic variability that exists in the overall collection, 2) identifies duplications in the collection, 3) recognizes where there is a lack of germplasm representing a species or geographic location, 4) simplifies evaluation especially for difficult and/or expensive traits, and 5) increases the utilization of the collection. There are currently two (2) core subsets related to Medicago, one each for the perennial and annual Medicago species. In addition, development of a Rhizobium meliloti core collection is currently under development. Perennial Medicago Core Subset The perennial Medicago core subset was developed by Drs. Daniel Basigalup, Don Barnes (USDA/ARS) and Robert Stucker at the University of Minnesota in 1989 through 1991. The core subset was selected from 1105 accessions representing 47 different countries and 4 species (M. sativa including the 6 subspecies (ssp. sativa, ssp. varia, ssp. falcata, ssp. coerulea, ssp. falcata, and ssp. ambigua), M. cancellata, M. platycarpa, and M. ruthenica. The 1105 accessions were assembled into 18 different groups based on the original collection site and their geographic proximity, i.e. one group was accessions collected in Hungary, Greece, Italy and Romania. These accessions were evaluated at Rosemount, Minnesota in 1989 for 21 morphological traits and 8 quality traits. Additional evaluation data on these accessions were obtained from the GRIN system including information on the resistance to 10 diseases and 5 insects, and salt and acid tolerance. Selection of the core was made by using cluster analysis to designate the most diverse accessions within each geographic proximity group. The core subset has 200 accessions (~18% of the evaluated accessions) with representatives from each species and geographic area (Basigalup, et. al., 1995). Recommendations: 1. The perennial Medicago core subset should receive high priority for increase, maintenance and evaluation of new traits, e.g. disease and insect resistance, quality traits, bypass proteins, water use efficiency, etc. 2. Specialty collections should be evaluated such as the highly non-dormant alfalfas (Steve Smith), the Chinese M. ruthenica collection (Austin Campbell and Larry Teuber), and the VIR collection in Russia. A core should be developed from this material by evaluating these collections in comparison to existing perennial Medicago core entries from the same geographic proximity group or species. Based on these evaluations the perennial Medicago core subset should be increased to represent the same frequency as the original core, i.e. about 15 - 20% of the specialty collection. 3. Additional germplasm collections are needed for secondary species ("wild" non-sativa species) from southeast China (Himalayan Mountains), southwest China, and southern Russia (Caucuses Mountains). 4. The core subset should be expanded as the number of accessions in the collection markedly increases. The new entries should be grown out and evaluated in comparison to existing perennial Medicago core entries from the same geographic proximity group or species. Annual Medic Core Subset The annual Medicago core subset was developed by Drs. Noa Diwan, Gary Bauchan (USDA-ARS, Beltsville, MD) and Marla McIntosh at the University of Maryland, College Park, Maryland from 1990 through 1992. The medic core subset was selected from 1220 accessions representing 34 annual Medicago species. These accessions were evaluated in Beltsville, Maryland in 1990 through 1992 for 15 morphological and agronomic traits (days to flower, days to full pod, biomass production within a species, biomass production among species, plant height, plant width (spread), growth habit, middle leaflet length, middle leaflet width, third internode length, pod production, pod spinyness, number of flowers/raceme, number of pods/raceme, and seed size). All of these data are available in the GRIN system. The selection for the core was made using cluster analysis with the final selection of core accessions within each cluster based on geographic location. The annual medic core subset has 211 accessions (~17% of the evaluated accessions) and 34 annual Medicago species are represented (Diwan, et al., 1994). The core collection was evaluated in six (6) locations across the U. S. (Athens, GA, Beltsville, MD, Ithaca, NY, Logan, UT, St. Paul, MN, and Tucson, AZ) for 11 traits (days to flower, days to full pod stage, full pod stage, growth habit, biomass within species, biomass among species, pod production, pod spinyness, plant height, plant width, and winter hardiness). All of these data are available in the GRIN system. Recommendations: 1. The annual Medicago core subset should receive high priority over the remaining collection for increase, maintenance and evaluation of additional traits especially freezing tolerance, disease and insect resistance. 2. The annual Medicago core subset should be evaluated for freezing tolerance, either to extend the autumn growth in the Mid-West or for over-wintering in milder climates such as California and south Texas 3. The annual Medicago core subset should be evaluated for disease resistance such as Anthracnose, Phytophthora, Fusarium, Rhizoctonia, Pythium, Leptosphearulina, Phoma, and Rust. These diseases have been seen on some of the annual medics which have been grown in the U.S. If the annual medics are to be grown in the U. S., we need to know in advance if there are any disease problems. 4. The annual Medicago core subset should be evaluated for insect resistance to aphids and leafhoppers. These insects have been seen on some of the annual medics which have been grown in the U. S. If the annual medics are to be grown in the U. S., we need to know in advance if there are any insect problems. 5. The annual Medicago core subset should be evaluated for isozyme and molecular marker traits such as RFLPs, RAPDs, and microsatellites to further evaluate the collection for redundancies. The annual Medicago species are all self-pollinating and are thus relatively uniform within an accession. 6. No new collection trips are needed for the annual medics. There is an extremely large germplasm collection of 23,000 accessions located in Adelaide, South Australia. If additional accessions are needed of a particular species they can be easily obtained from this collection. Rhizobium Collection A comprehensive collection of R. meliloti isolates has been developed at St. Paul, Minnesota. It consists of a domestic collection (U. S. and Canadian) that was initiated by W. R. Ellis in 1979. That collection was formed by requesting alfalfa scientists in nearly all states and provinces to send nodules collected from up to four of the best adapted cultivars. We requested that whenever possible nodules from Saranac and Saranac AR be included in each locations' collection. An international collection was initiated by S. E. Viteri in 1987 using the same procedures of contacting alfalfa scientists. In addition, collections from Western Australia (Howieson), Napal and Pakistan (Rumbaugh), Turkey (Elgin), and the USDA (Beltsville, VanBerkum) were also included in the Minnesota collection. Each isolate was isolated from an individual nodule, increased in culture, inoculated onto plants from a broadbased Medicago sativa gene pool (BIC-7), and then reisolated from an effective nodule. All isolates were further tested to insure that they were R. meliloti. The entire collection was evaluated for reaction to 13 antibiotic and 14 bacteriophages. By considering these evaluations it was possible to eliminate similar isolates from each original collection location. For example, seventeen isolates from two Georgia fields were tested for bacteriophage reaction. Only two isolates had a similar profile of reactions. Similarly the two isolates were reconfirmed with the antibiotic evaluation. After all duplicate isolates were discarded the collection consisted of 641 isolates. All of these isolates were deposited in 1990 in the World Rhizobium Culture Collection in the Soybean and Alfalfa Research Lab., Beltsville, Maryland, Peter VanBerkum, curator. All of the isolates have been assigned a USDA accession number and have been placed in cold storage for long-term preservation. Recommendations: 1. A core subset needs to be developed using the data available in the GRIN system utilizing cluster analysis to identify subgroups. The final core subset should consist of between 65 to 75 isolates. 2. Once the core subset is established, the core should be evaluated for tolerance to low pH conditions. The isolates should be evaluated for both free living tolerance and symbiotic tolerance to low soil pH conditions. 3. Once the core subset is established, a determination of the symbiotic effectiveness of the core collection on the Medicago species core subsets should be conducted. 4. Any additional Rhizobium isolates should be sent to Dr. VanBerkum. Once a significant number of isolates has been added to the collection they should be evaluated in comparison to the core subset. 5. Evaluate the collection for Rhizobium strains by plant genotype interaction. There is a reasonable amount of information from other Rhizobia that there can be a substantial strain by cultivar origin. Since we recently identified strains of Rhizobia that will infect both alfalfa and soybean in China it seams likely that we could expect some significant interactions between genotypes from diverse locations. In a study that Don Barnes and I reported on we noticed some marked difference in the Rhizobia obtained from the same genotypes in different locations. Assessing the collection for current gaps The technical advances of molecular genetics, and interest in developing more sustainable agricultural systems, coupled with the continued rise in loss of biodiversity, have prompt us to closely examine the current contents of the collection to determine if it meets the needs of a broad array of users and conservation objectives. The Convention on Biological Diversity necessitates that this examination occur within the context that nations have sovereign rights over the genetic resources that originate within their boundaries. Recommendations:
Species Related to Alfalfa Primary Gene Pool
Modern and obsolete cultivars Landraces Ecotypes
Secondary Gene Pool
Tertiary Gene Pool
Primary Gene Pool (Medicago sativa subsp. sativa) Obsolete and current cultivars The following table indicates the number of alfalfa cultivars maintained in the NPGS collection. Although the collection contains more cultivars, these accessions have been verified as registered cultivars that were directly donated by the country that released them. Table 5. Number of accessions in the primary gene pool and their country of origin.
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