Syntenic relationships between Medicago truncatula and Arabidopsis reveal extensive divergence of genome organization

Hongyan Zhu, Dong Jin Kim, Jong Min Baek, Hong Kyu Choi, Leland C. Ellis, Helge Küester, W. Richard McCombie, Hui Mei Peng, Douglas R. Cook

Research output: Contribution to journalArticlepeer-review

62 Scopus citations


Arabidopsis and Medicago truncatula represent sister clades within the dicot subclass Rosidae. We used genetic map-based and bacterial artificial chromosome sequence-based approaches to estimate the level of synteny between the genomes of these model plant species. Mapping of 82 tentative orthologous gene pairs reveals a lack of extended macrosynteny between the two genomes, although marker collinearity is frequently observed over small genetic intervals. Divergence estimates based on non-synonymous nucleotide substitutions suggest that a majority of the genes under analysis have experienced duplication in Arabidopsis subsequent to divergence of the two genomes, potentially confounding synteny analysis. Moreover, in cases of localized synteny, genetically linked loci in M. truncatula often share multiple points of synteny with Arabidopsis; this latter observation is consistent with the large number of segmental duplications that compose the Arabidopsis genome. More detailed analysis, based on complete sequencing and annotation of three M. truncatula bacterial artificial chromosome contigs suggests that the two genomes are related by networks of microsynteny that are often highly degenerate. In some cases, the erosion of microsynteny could be ascribed to the selective gene loss from duplicated loci, whereas in other cases, it is due to the absence of close homologs of M. truncatula genes in Arabidopsis.

Original languageEnglish
Pages (from-to)1018-1026
Number of pages9
JournalPlant Physiology
Issue number3
StatePublished - Mar 1 2003

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science


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