Submitted to: Genome
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/2003
Publication Date: 2/1/2004
Citation: Yan, H., Mudge, J., Kim, D., Shoemaker, R.C., Cook, D., Young, N.D. 2004. Comparative physical mapping reveals features of microsynteny between the genomes of glycine max and medicago truncatula. Genome. v. 47. p.141-155. Interpretive Summary: The ability to make inferences about the hereditary mechanisms of one species, based on what we learn in another species would save millions of research dollars. In this paper the authors report that the organization of the hereditary material in two different legumes may be only moderately similar to the organization of the hereditary material in the model plant, Arabidopsis. Thus, the genetic information obtained from the millions of research dollars spent on Arabidopsis may not be easily related to soybean or to the other legume, a relative of alfalfa. The authors also report that the evolutionary history of one of the legumes, an economically important crop, soybean, may be more complex than previously thought. The results of this study will be very important to scientists interested in studying the organization of the chromosomes in legumes and in many other plants not closely related to the plant model, Arabidopsis.
Technical Abstract: A hybridization-based approach was used to estimate genome-wide microsynteny between genomes of Medicago truncatula, Glycine max and Arabidopsis thaliana. A total of 187 soybean BAC subclones and RFLP probes, plus 106 whole BAC clones from genetically mapped contigs were used. Restriction fragment analysis and Southern blot hybridization experiments confirmed that these probes did not contain repetitive DNA. Limited conserved microsynteny was inferred when at least two probes from a soybean contig hybridized to a common Medicago BAC. Extensive conserved microsynteny was inferred when a whole soybean BAC clone hybridized to five or more fragments from a Medicago BAC. Of the 50 soybean contig groups examined, 54% showed conserved microsynteny to the Medicago genome, including 38% with extensive and 16% with limited conserved microsynteny. In a similar strategy, the degree of conservation among soybean homoeologues was also investigated. The results indicated substantial conservation among soybean homoeologues, with 67.6% showing extensive and 29.7% showing limited conserved microsynteny. To best explain the extent of conserved microsynteny among duplicated soybean contigs as well as the number of BAC contigs identified by each RFLP probe we suggest that at least two rounds of large-scale duplications have occurred in the soybean lineage. A sequence-based homology search was also performed between 50 soybean contig groups and the Arabidopsis genome. Depending upon the stringency level, between 6% and 12% of the soybean contig groups exhibited conserved microsynteny with Arabidopsis.