U.S. Medicago Germplasm Collection:
Celebrating a Century of Plant Collecting, Introduction and Conservation
Stephanie L. Greene
USDA, National Plant Germplasm System, Washington State University, Prosser, WA 99350.
The year 1998 marks the centennial for many USDA germplasm collections in the United States. In 1898,
the USDA Division of Botany, Section of Seed and Plant Introduction began assigning Plant Introduction
(PI) numbers to seed and plants brought into the United States. The first alfalfa PIs were collected in
Russia and Central Asia in 1897 by the plant explorer, N.E. Hansen, a horticulturalist at the South Dakota
Agricultural Experiment Station. The source of much of the M. sativa ssp. falcata and M. sativa nothossp.
varia germplasm used in the United States can be traced back to these specific seed lots. In fact, most of
the nine germplasm sources that contributed to the development of alfalfa in the United States, can be
traced back to specific seed lots brought into the country through the Plant Introduction program. Today,
the Medicago germplasm collection contains more than 7,100 accessions, representing 72 of the 85 species
in the genus. Reflecting a historic mandate of introduction, 90 % of the collection represents the
cultivated gene pool of either alfalfa or the annual species. The U.S. collection plays a limited role in the ex
situ conservation of the non-cultivated primary and secondary genepool. The table below compares the
number of accessions that represent the primary and secondary alfalfa (Medicago sativa ssp. sativa) gene
pool.
| Category | ssp.
sativa | ssp.
falcata | nothossp.
varia | nothossp.
polychroa | M.
prostrata | ssp.
glomerata | nothossp.
tunetana | ssp.
caerulea | M.
papillosa |
| Breeding | 358 | 11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Cultivar | 787 | 21 | 106 | 0 | 0 | 0 | 0 | 0 | 0 |
| Cultivated | 288 | 50 | 14 | 0 | 0 | 2 | 1 | 16 | 0 |
| Landrace | 614 | 20 | 63 | 0 | 0 | 0 | 0 | 0 | 0 |
| Uncertain | 386 | 18 | 17 | 0 | 0 | 0 | 0 | 16 | 0 |
| Wild | 366 | 276 | 76 | 0 | 13 | 5 | 5 | 45 | 9 |
| 2799 | 396 | 276 | 0 | 13 | 7 | 6 | 77 | 9 |
(GRIN, June 1998. Taxonomy based on Wiersma et al. 1990)
Annual species in the tertiary gene pool are well represented, largely due to the inclusion of the K.A. Lesin's collection in the
1980's. However, only 13 perennial species are represented in the tertiary gene pool. An extensive revision of the NPGS
Medicago database has been recently completed and is available to the public at the GRIN website (http://www.ars
grin.gov/npgs). Seed requests can also be made at the website. The extensive upgrade of the passport information will provide
the collection curator and CGC members the opportunity to examine the contents of the collection at a level of detail not
previously possible. As the century draws to a close, it seems appropriate to carry out such an examination to ensure the U.S.
Medicago germplasm collection effectively serves the dual role of conserving and encouraging the use of diverse Medicago
genetic resources in the 21st. Century.
- Wiersma, J.H., J.H. Kirkbride Jr., C. R. Gunn. 1990. Legume Nomenclature in the USDA Germplasm System. USDA
Technical Bulletin No. 1757, 572 pp.
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