Medicago truncatula

Common NameMedicago

Medicago truncatula (Barrel Medic or Barrel Medick or Barrel Clover) is a small annual legume native to the Mediterranean region that is used in genomic research. It is a low-growing, clover-like plant 10–60 cm tall with trifoliate leaves. Each leaflet is rounded, 1–2 cm long, often with a dark spot in the center. The flowers are yellow, produced singly or in a small inflorescence of 2-5 together; the fruit is a small spiny pod.

This species has been chosen as a model organism for legume biology because it has a small diploid genome, is self-fertile, has a rapid generation time and prolific seed production, and is amenable to genetic transformation.

It forms symbioses with nitrogen-fixing rhizobia (Sinorhizobium meliloti and Sinorhizobium medicae) and arbuscular mycorrhizal fungi. The model plant Arabidopsis thaliana does not form either symbiosis, making M. truncatula an important tool for studying these processes.

Property NameValue
Modal Chromosome Number2n = 8
Taxonomycellular organisms; Eukaryota; Viridiplantae; Streptophyta; Streptophytina; Embryophyta; Tracheophyta; Euphyllophyta; Spermatophyta; Magnoliophyta; Mesangiospermae; eudicotyledons; Gunneridae; Pentapetalae; rosids; fabids; Fabales; Fabaceae; Papilionoideae; Trifolieae; Medicago
Sequence & Variant Data
The following sequence and variant data are currently present:
Feature TypeCount
<ul><li>Preparation of EST data: Sequences were extracted from dbEST and were subjected to quality control screening (vector, E. coli, polyA, T, or CT removal, minimum length = 100 bp, &lt; 3% N).</li><li>Preparation of transcript (ET) database: All sequences from the appropriate divisions of GenBank (including RefSeq) were extracted. Non-coding sequences were discarded and cDNAs and coding sequences from genomic entries were saved. Sequences and related information (e.g. PubMed links) are stored in the qcGene database (qcGene).</li><li>Assembly: Cleaned EST sequences and non-redundant transcript (ET) sequences were combined. Using the Paracel Transcript Assembler Program, sequences were assembled into contigs. TCs are consensus sequences based on two or more ESTs (and possibly an ET) that overlap for at least 40 bases with at least 94% sequence identity. These strict criteria help minimize the creation of chimeric contigs. These contigs are assigned a TC (Tentative Consensus) number. TCs may comprise ESTs derived from different tissues. The best hits for TC's were assigned by searching the TC set against a non-redundant amino acid database(nraa) using BLAT. The top five hits based on score were selected and displayed for each TC.</li><li>Caveats: TCs are only as good as the ESTs underlying them; there may be unspliced or chimeric ESTs and thus TCs. There is still redundancy in the TC set because sequences must match end to end and at a certain percent identity to be combined. Directionality of the TCs should not be assumed. Not all TCs contain protein-coding regions.</li></ul>
The Medicago truncatula sequencing project was initiated with a generous grant from Samuel Roberts Noble Foundation to the University of Oklahoma. Beginning in 2003 (and renewed in 2006), the National Science Foundation and the European Union's Sixth Framework Programme provided funding to complete sequencing of the remaining euchromatic genespace. Among the eight chromosomes in Medicago, six are being sequenced by NSF project "Sequencing the Gene Space of the Model Legume, Medicago Truncatula," and two are being sequenced by partners in Europe. Nevin Young (University of Minnesota), Bruce Roe (ACGT, University of Oklahoma; chromosomes 1, 4, 6, 8), and Chris Town (TIGR; chromosomes 2, 7) are principal investigators of the U.S. project. In Europe, collaborators include Giles Oldroyd (John Innes Center) coordinating sequencing of chromosome 3 at the Sanger Center, and Frederic Deballe (INRA-CNRS) coordinating sequencing of chromosome 5 at Genoscope. The genome annotation was carried out by the International Medicago Genome Annotation Group (IMGAG), which involves participants from TIGR, INRA-CNRS, MIPS, UMN, Ghent University and NCGR.