The Population Genetic Structure of Diploid Medicago sativa L. Germplasm

  • Muhammet Sakiroglu
  • Jeffrey J. Doyle
  • E. Charles Brummer
Conference paper


The three subspecies Medicago sativa subsp. caerulea (syn. coerulea), M. sativa subsp. falcata, and M. sativa subsp. hemicycla are considered to form the diploid gene pool of cultivated alfalfa (M. sativa subsp. sativa). The diploid gene pool is underutilized in breeding programs despite extensive morphological variation and the simplicity of disomic inheritance. Population structure and the genetic basis of the current morphologically-based classification of diploid germplasm are not known. We analyzed the population genetic structure of wild diploid alfalfa germplasm by evaluating 374 individual genotypes from 120 accessions, representing the broad natural variation of the three subspecies, with 89 microsatellite markers. We found that the three subspecies formed distinct clusters, with evidence of further subdivision of falcata and caerulea into two subclusters each. The genetic distinction between the two falcata subclusters is more definitive than that of the two caerulea groups. Genome composition suggests extensive gene flow where subspecies and/or groups within subspecies grow sympatrically. The results will help breeders identify appropriate diploid accessions to maximize diversity in applied germplasm development.


Genetic diversity Medicago sativa Population structure SSR markers 



We would like to thank Yanling Wei for technical assistance; the Turkish Government for funding Muhammet Şakiroğlu; and the National Research Initiative (NRI) Plant Feedstock Genomics for Bioenergy Program for funding this project.


  1. Diwan, N., Bouton, J.H., Kochert, G., Cregan, P.B. 2000. Mapping of Simple Sequence Repeat (SSR) DNA Markers in Diploid and Tetraploid Alfalfa. Theor. Appl. Genet. 101:165–172.Google Scholar
  2. Doyle, J.J., Doyle, J.L. 1987. A rapid DNA isolation for small quantities of fresh leaf tissue. Phytochem. Bull. 19:11–15.Google Scholar
  3. Evanno, G., Regnaut, S., Goudet, J. 2005. Detecting the number of clusters of individuals using the software structure: A simulation study. Mol. Ecol. 14:2611–2620.PubMedCrossRefGoogle Scholar
  4. Julier, B., Flajoulot, S., Barre, P., Cardinet, G., Santoni, S., Huguet, T., Huyghe C. 2003. Construction of two genetic linkage maps in cultivated tetraploid alfalfa (Medicago sativa) using microsatellite and AFLP markers. BMC Plant Biol. 3:9.PubMedCrossRefGoogle Scholar
  5. Kaló, P., Endre, G., Zimányi, L., Csanádi, G., Kiss, G.B. 2000. Construction of an Improved Linkage Map of Diploid Alfalfa (Medicago sativa). Theor. Appl. Genet. 100:641–657.Google Scholar
  6. Lesins, K., Lesins, I. 1979. Genus Medicago (Leguminasae): A taxogenetic study. Kluwer, Dordrecht, Netherlands.CrossRefGoogle Scholar
  7. McCoy, T.J., Bingham E.T. 1988. Cytology and cytogenetics of Alfalfa (pp. 739–776). In: Hanson, A.A., et al. (eds.), Alfalfa and alfalfa improvement. ASA-CSSA-SSSA, Madison, WI, USA.Google Scholar
  8. Michaud, R., Lehman, W.F., Rumbaugh, M.D. 1988. World distribution and historical development (pp.25–91). In: Hanson, A.A., Barnes, D.K., Hill, R.R. (eds.), Alfalfa and Alfalfa Improvement. ASA-CSSA-SSSA, Madison, WI, USA.Google Scholar
  9. Pritchard, J.K., Stevens, M., Donnelly, P. 2000. Inference of population structure using multilocus genotype data. Genetics 155:945–959.PubMedGoogle Scholar
  10. Quiros, C.F., Bauchan, G.R. 1988. The genus Medicago and the origin of the Medicago sativa complex (pp. 93–124). In: Hanson, A.A., et al. (eds.), Alfalfa and alfalfa improvement. ASA-CSSA-SSSA, Madison, WI, USA.Google Scholar
  11. Robins, J.G., Luth, D., Campbell, T.A., Bauchan, G.R., He, C., Viands, D.R., Hansen, J.L., Brummer, E.C. 2007. Genetic mapping of biomass production in tetraploid alfalfa (Medicago sativa L.). Crop Sci. 47:1–10.CrossRefGoogle Scholar
  12. Şakiroğlu, M., Doyle, J.J., Brummer, E.C. 2009. Inferring population structure and genetic diversity of a broad range of wild diploid alfalfa (Medicago sativa L.) accessions using SSR markers. Theor. Appl. Genet. [in review].Google Scholar
  13. Schuelke, M. 2000. An economic method for the fluorescent labeling of PCR fragments. Nat. Biotechnol. 18:233–234.PubMedCrossRefGoogle Scholar
  14. Sledge, M.K., Ray, I.M.,. Jiang, G. 2005. An expressed sequence tag SSR map of tetraploid alfalfa (Medicago sativa L.). Theor. Appl. Genet. 111:980–992.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Muhammet Sakiroglu
    • 1
  • Jeffrey J. Doyle
    • 1
  • E. Charles Brummer
    • 1
  1. 1.Institute for Plant Breeding, Genetics, and GenomicsUniversity of GeorgiaAthensUSA

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