|Specht James E|
|Bhagwat Arvind A|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/6/1995
Publication Date: N/A
Citation: Interpretive Summary: Genetic markers are used to create "road maps" of the chromosomes of plant and animal species. The positions of genes controlling important traits such as disease resistance or seed protein and oil quantity or quality in soybean can then be established in reference to the genetic markers or "milestones" on the genetic map. When a marker is situated near a gene controlling a trait of interest, the plant breeder can use the marker to select for the trait of interest and thereby avoid the cost and time required to assess the level of resistance or the level of the protein or oil in the seed. The purpose of this work was to create a genetic map of soybean using Simple Sequence Repeat (SSR) DNA markers that we have recently shown to be very useful in soybean genetic studies. A total of 40 SSR markers were identified and genetically mapped along with a group of about 120 other DNA markers as well as genes controlling a number of morphological and pigmentation traits in soybean. The SSR markers appeared to be evenly distributed throughout the soybean genome and situated very near a number of genes controlling important morphological and pigmentation traits in soybean. This new type of DNA marker should provide an excellent complement to currently available DNA markers and will be useful in soybean improvement and for more basic research in soybean molecular biology including gene isolation.
Technical Abstract: A total of 40 simple sequence repeat (SSR) or microsatellite DNA markers were mapped in a soybean mapping population that consisted of 60 F2 plants from a cross between near isogenic lines of the cultivars Clark and Harosoy. The first objective of study was to determine the map location of SSR loci in relation to 13 classical loci controlling pigmentation and morphological traits, seven isozyme loci, and a total of 118 RFLP and RAPD markers. The second objective was to determine if the microsatellite loci were randomly distributed in the soybean genome. Linkage analysis using MAPMAKER 3.0b yielded 29 linkage groups with a total map length of 1486 centimorgans. This compares to a map length of 1056 cM if the SSR markers were removed from the data set. Thirty-four of the microsatellite loci were placed in linkage groups. SSR loci were linked to loci controlling 9 of the 13 classical traits, and two of seven isozyme loci. Eighteen of the 29 linkage groups contained at least one SSR locus. While this result suggested that the microsatellite loci were randomly distributed throughout the soybean genome, two clusters of five and four SSR loci, spanning 23.4 cM and 33.6 cM, respectively, were detected. These results indicated a relatively limited amount of clustering of soybean SSR loci, and demonstrated that microsatellite genetic markers should provide an excellent complement to RFLP and RAPD markers for use in soybean molecular biology, genetics, and breeding research. Because SSR markers detect only single genetic loci and are highly polymorphic, they can be extremely informative in pedigree tracing studies, in the analysis of progeny from multiparent matings, in a wide range of mapping applications, and in genotype identification.