Submitted to: Genetics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/6/2006
Publication Date: 3/1/2006
Citation: Walling, J., Shoemaker, R.C., Young, N., Mudge, J., Jackson, S. 2006. Chromosome levelhomeology in paleopolyploid soybean (Glycine max) revealed through integration of genetic and chromosome maps. Genetics. 172:1893-1900. Interpretive Summary: Recent advances in technology has made it possible to obtain the entire genetic code of some crop plants. Understanding how chromosomes are organized is important to planning strategies for obtaining this genetic code. In this research the authors translated information from the genetic roadmap of one soybean chromosome to the chromosome itself. They overlaid the roadmap onto a picture of the chromosome. This confirmed that much of the important DNA on this chromosome is limited to the region defined by the roadmap. Understanding how this chromosome is organized and being able to relate its structure to a genetic map will make it possible to design experiments to decode its genes. This information is critical to scientists wishing to advance our knowledge of gene function in this major legume crop.
Technical Abstract: Soybean has 20 chromosome pairs that are derived from at least two rounds of genome-wide duplication or polyploidy events; although, cytogenetically, soybean behaves like a diploid and has disomic inheritance for most loci. Genetically-anchored genomic clones were used as probes for fluorescence in situ hybridization (FISH) to determine the level of post-polyploid chromosomal re-arrangements and to integrate the genetic and physical maps in order to 1) assign linkage groups to specific chromosomes, 2) assess chromosomal structure, and 3) determine the distribution of recombination along the length of a chromosome. FISH mapping of seven putatively gene-rich BACs from linkage group L (chromosome 19) revealed that most of the genetic map correlates to the long, highly euchromatic long arm and that there is extensive homeology with another chromosome pair, although, colinearity of loci does appear to be disrupted. Moreover, mapping of BACs containing high-copy sequences revealed sequestration of high-copy repeats to the pericentromeric regions of this chromosome. Taken together these data present a model of chromosome structure in a highly duplicated but diploidized eukaryote, soybean.