Medicago Explained

Medicago is a genus of flowering plants, commonly known as medick or burclover, in the legume family (Fabaceae). It contains at least 87 species and is distributed mainly around the Mediterranean Basin,[1] [2] and extending across temperate Eurasia and sub-Saharan Africa. The best-known member of the genus is alfalfa (M. sativa), an important forage crop,[3] and the genus name is based on the Latin name for that plant, Latin: medica, from Greek, Modern (1453-);: μηδική (πόα) Median (grass).[4] Most members of the genus are low, creeping herbs, resembling clover, but with burs (hence the common name). However, alfalfa grows to a height of 1 meter, and tree medick (M. arborea) is a shrub. Members of the genus are known to produce bioactive compounds such as medicarpin (a flavonoid) and medicagenic acid (a triterpenoid saponin). Chromosome numbers in Medicago range from 2n = 14 to 48.[5]

The species Medicago truncatula is a model legume[6] due to its relatively small stature, small genome (450–500 Mbp), short generation time (about 3 months), and ability to reproduce both by outcrossing and selfing.

Comprehensive descriptions of the genus are Lesinš and Lesinš 1979[7] and Small and Jomphe 1989.[8] Major collections are SARDI (Australia),[9] USDA-GRIN (United States),[10] ICARDA (Syria),[11] and INRA (France).[12]

Evolution

Medicago diverged from Glycine (soybean) about 53–55 million years ago (in the early Eocene),[13] from Lotus (deervetch) 49–51 million years ago (also in the Eocene), and from Trigonella 10–22 million years ago (in the Miocene).[14]

Ecological interactions with other organisms

Symbiosis with nitrogen-fixing rhizobia

Béna et al. (2005) constructed a molecular phylogeny of 23 Sinorhizobium strains and tested the symbiotic ability of six strains with 35 Medicago species.[15] Comparison of these phylogenies indicates many transitions in the compatibility of the association over evolutionary time. Furthermore, they propose that the geographical distribution of strains limits the distribution of particular Medicago species.

Agricultural uses

Agronomic research has been conducted on species of the Medicago genus. Other than alfalfa, several of the prostrate members of the family (such as Medicago lupulina and Medicago truncatula) have been used as forage crops.[16] Select species in the Medicago genus naturally develop spiney pods during the reproductive phase of growth (such as Medicago intertexta and Medicago polymorpha). Despite having high levels of agronomic performance, these are typically viewed as undesirable in sheep based farming systems due to their ability to become lodged in wool, reducing fleece value.[17] Breeding efforts in the 1990's have yielded spineless varieties of burr medic, providing valuable production amongst farming systems in low rainfall (<300mm annual), free draining, alkaline soils.[18]

Insect herbivores

Medicago species are used as food plants by the larvae of some Lepidoptera species including the common swift, flame, latticed heath, lime-speck pug, nutmeg, setaceous Hebrew character, and turnip moths and case-bearers of the genus Coleophora, including C. frischella (recorded on M. sativa) and C. fuscociliella (feeds exclusively on Medicago spp.).

Species

This list is compiled from:[19] [20] [21] [22] [23] [24] [25] [26] [27] [28]

Section Buceras

Subsection Deflexae

Subsection Erectae

Subsection Isthmocarpae

Subsection Reflexae

Section Carstiensae

Section Dendrotelis

Section Geocarpa

Section Heynianae

Section Hymenocarpos

Section Lunatae

Section Lupularia

Section Medicago

Section Orbiculares

Section Platycarpae

Subsection Rotatae

Section Spirocarpos

Subsection Intertextae

Subsection Leptospireae

Subsection Pachyspireae

Species names with uncertain taxonomic status

The status of the following species is unresolved:

Recent molecular phylogenic analyses of Medicago indicate that the sections and subsections defined by Small & Jomphe, as outlined above, are generally polyphyletic.[30] [31] [32] [33] [34] However, with minor revisions sections and subsections could be rendered monophyletic.

Notes and References

  1. Steele KP, Ickert-Bond SM, Zarre S, Wojciechowski MF . Phylogeny and character evolution in Medicago (Leguminosae): Evidence from analyses of plastid trnK/matK and nuclear GA3ox1 sequences . . 97 . 7 . 1142–1155 . 2010 . 21616866 . 10.3732/ajb.1000009 . free .
  2. Gholami A, De Geyter N, Pollier J, Goormachtig S, Goossens A . Natural product biosynthesis in Medicago species . Natural Product Reports . 2014 . 31 . 3 . 356–380 . 24481477 . 10.1039/C3NP70104B .
  3. Web site: Alfalfa Crop Germplasm Committee Report, 2000 . 2009-11-04 . https://web.archive.org/web/20090505235641/http://www.ars-grin.gov/npgs/cgc_reports/alfalfa/alfalfacgc2000.htm . 2009-05-05 . dead .
  4. New Oxford American Dictionary (2nd ed., 2005), p. 1054, s.v. medick.
  5. Rosato M, Galián JA, Rosselló JA . Amplification, contraction and genomic spread of a satellite DNA family (E180) in Medicago (Fabaceae) and allied genera . . 109 . 4 . 773–82 . 2012 . 10.1093/aob/mcr309 . 22186276 . 3286279 .
  6. Web site: Medicago truncatula . 21 November 2008 . https://web.archive.org/web/20081229224731/http://www.medicago.org/ . 29 December 2008 . dead .
  7. Book: Lesinš KA, Lesinš I . Genus Medicago (Leguminosae): A Taxogenetic Study . Dr. W. Junk B. V. Publishers . 1979 . The Hague, The Netherlands . 132 . 978-90-6193-598-8 .
  8. Small E, Jomphe M . A Synopsis of the Genus Medicago (Leguminosae) . . 67 . 11 . 3260–94 . 1989 . 10.1139/b89-405 .
  9. Web site: SARDI . 21 November 2008 . https://web.archive.org/web/20081026034951/http://www.sardi.sa.gov.au/ . 26 October 2008 . dead .
  10. Web site: GRIN National Genetic Resources Program . 21 November 2008 . 14 August 2009 . https://web.archive.org/web/20090814093722/http://www.ars-grin.gov/sitemapgrin.html . dead .
  11. Web site: ICARDA Sustainable Agriculture for the Dry Areas . 21 November 2008 . https://web.archive.org/web/20081211213141/http://www.icarda.org/ . 11 December 2008 . dead .
  12. Web site: INRA . 21 November 2008 . https://web.archive.org/web/20100731172517/http://www1.montpellier.inra.fr/BRC-MTR/ . 31 July 2010 . dead .
  13. Book: Cannon S. . Stacey G . Genetics and Genomics of Soybean . Plant Genetics and Genomics: Crops and Models . II . 2008 . Springer . New York, NY . 978-0-387-72298-6 . 38 . 3. Legume Comparative Genomics . http://ddr.nal.usda.gov/bitstream/10113/17513/1/IND44083204.pdf .
  14. Maureira Butler IJ, Pfeil BE, Muangprom A, Osborn TC, Doyle JJ . The reticulate history of Medicago (Fabaceae) . . 57 . 6 . 466–482 . 2008 . 18570039 . 10.1080/10635150802172168 . free .
  15. Béna G, Lyet A, Huguet T, Olivier I . Medicago–Sinorhizobium symbiotic specificity evolution and the geographic expansion of Medicago . J. Evol. Biol. . 18 . 6 . 1547–58 . 2005 . 16313467 . 10.1111/j.1420-9101.2005.00952.x . 24813001 . free .
  16. http://extension.msstate.edu/content/black-medic-medicago-lupulina
  17. https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0009/176688/Naturalised-pasture-legumes.pdf
  18. https://keys.lucidcentral.org/keys/v3/pastures/Html/Spineless_burr_medic.htm
  19. Web site: ILDIS LegumeWeb. 2008-11-18. dead. https://web.archive.org/web/19991007023041/http://www.ildis.org/LegumeWeb/. 1999-10-07.
  20. Web site: Genera Containing Currently Accepted Names: Medicago . 2008-11-18 . dead . https://web.archive.org/web/20080930231937/http://www.ildis.org/LegumeWeb/6.00/names/npall/npall_445.shtml . September 30, 2008 .
  21. Web site: Species Nomenclature in GRIN . https://web.archive.org/web/19990501235849/http://www.ars-grin.gov/cgi-bin/npgs/html/genform.pl . dead . 1999-05-01 . 2008-11-18 .
  22. Web site: IPNI Plant Name Query Results. 2008-11-22.
  23. Web site: AgroAtlas - Relatives. 2008-11-22. https://web.archive.org/web/20081225182412/http://www.agroatlas.spb.ru/en/content/related/#M. 2008-12-25. dead.
  24. Web site: ITIS . 2009-09-16 . dead . https://web.archive.org/web/20160606043808/http://www.itis.gov/index.html . 2016-06-06 . (enter Medicago as the search term)
  25. Web site: Discover Life. 2010-05-11. https://web.archive.org/web/20110612032141/http://www.discoverlife.org/mp/20q?search=Medicago. 2011-06-12. dead.
  26. http://www.efloras.org/browse.aspx?flora_id=1&name_str=Medicago&btnSearch=Search&chkAllFloras=on eFloras
  27. http://www.bonap.org/dist%20maps%202009/Medicago.html The Biota of North America Program
  28. Web site: The Plant List . 2011-06-27 . 2019-03-26 . https://web.archive.org/web/20190326042049/http://www.theplantlist.org/tpl/search?q=Medicago . dead .
  29. Gillespie DJ, McComb JA . Morphology and distribution of species in the Medicago murex complex . . 69 . 12 . 2655–2662 . 1991 . 10.1139/b91-333 .
  30. Béna G, Lejeune B, Prosperi JM, Olivieri I . Molecular phylogenetic approach for studying life-history evolution: the ambiguous example of the genus Medicago L. . . 265 . 1401 . 1141–1151 . 1998 . 9684377 . 1689169 . 10.1098/rspb.1998.0410 .
  31. Downie SR, Katz-Downie DS, Rogers EJ, Zujewski HL, Small E . Multiple independent losses of the plastid rpoC1 intron in Medicago (Fabaceae) as inferred from phylogenetic analyses of nuclear ribosomal DNA internal transcribed spacer sequences . . 76 . 5 . 791–803 . 1998 . 10.1139/b98-047 .
  32. Béna G, Prosperi JM, Lejeune B, Olivieri I . Evolution of annual species of the genus Medicago: a molecular phylogenetic approach . . 9 . 3 . 552–559 . 1998 . 10.1006/mpev.1998.0493 . 9668004 . 1998MolPE...9..552B .
  33. Béna G. . Molecular phylogeny supports the morphologically based taxonomic transfer of the "medicagoid" Trigonella species to the genus Medicago L. . . 229 . 3–4 . 217–236 . 2001 . 10.1007/s006060170012 . 2001PSyEv.229..217B . 42887106 .
  34. Yoder JB, Briskine R, Mudge J, Farmer A, Paape T, Steele K, Weiblen GD, Bharti AK, Zhou P, May GD, Young ND, Tiffin P . Phylogenetic signal variation in the genomes of Medicago (Fabaceae) . . 62 . 3 . 424–38 . 2013 . 10.1093/sysbio/syt009 . 23417680 . free .

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