Medicago truncatula Gaertn. Germplasm Collection
The USDA-ARS National Plant Germplasm System (NPGS) temperate forage legume collection hosts the Medicago truncatula Gaertn. collection. Limited quantities of seed are freely available to requestors in order to support research and breeding objectives around the world.
The first NPGS M. truncatula accession was received in 1950, when a commercial strain and 9 unimproved samples were received from J.R.A. McMillan from the University of Sydney, New South Wales, Australia. Currently, the collection includes 387 available ecotypes of M. truncatula, originating from 22 countries. Over 50% of the accessions were collected in Algeria, Morocco and Tunisia. A collaborative collection effort was carried out in 1973 in Morocco by I. Forbes, of the United States Department of Agriculture and J.S. Gladstones of the Australian Department of Agriculture. W. Graves, of the University of California also made extensive contributions from collections in Morocco and Tunisia in the early 1980s. Approximately 55% of the collection was received in the late 1980’s, when the NPGS inherited the germplasm collection of the late Canadian taxonomist, Dr. Karl A. Lesins. Most of the accessions (80% of collection total) in the M. truncatula collection are unimproved or wild germplasm. Another 15-20% of the collection is either cultivars or breeding materials. A large portion of the cultivated germplasm has been obtained from ex situ germplasm collection in Australia. The collection is being strategically and actively expanded to include important genetic stocks that are being developed by the genomics community. To find additional information regarding the accessions in the M. truncatula collection the Germplasm Resources Information Network (GRIN-Global) database can be queried.
Storage and Regeneration
The collection is housed and distributed from the Western Regional Plant Introduction Station located in Pullman, Washington. The project’s mission is to maintain the genetic diversity inherent in the collected germplasm. Although most of the annual medic species are self-pollinated, they are surprisingly heterogeneous, and are treated as populations. Distribution seed lots are stored at 4°C and 30% relative humidity. Original and regeneration seed lots are stored at 4°C and are gradually being relocated to a -20°C freezer. All regeneration, characterization and evaluation efforts are carried out at the worksite in Prosser, WA, collocated with WSU’s Irrigated Agriculture Research and Extension Center. Seed is sown in greenhouses each spring and transplanted to the field. To minimize genetic erosion during seed increase, approximately 100 individual plants are used. Although M. truncatula is a self-pollinated species, individual accessions are isolated in cages since a small but genetically significant level of cross pollination has been reported for this species.
Characterization and evaluation are an important part of the project’s objectives. In 2003, extensive morphological evaluation of the entire M. truncatula collection was carried out. Objectives were to characterize the length of growth stages, as well as the morphological features of leaves, branches, flowers and fruit for each accession. Data can be downloaded and examined by accessing the GRIN-Global database.
Interested in obtaining germplasm seed? Request germplasm online registering and selection germplasm at GRIN-Global (https://npgsweb.ars-grin.gov) or contact temperate forage legume Curator, Dr. Brian M. Irish.