Author
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Cregan, Perry |
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Submitted to: Soybean Research World Conference Proceedings
Publication Type: Proceedings Publication Acceptance Date: 8/2/1999 Publication Date: N/A Citation: N/A Interpretive Summary: DNA markers serve as genetic landmarks and are interspersed among the 50,000 or more genes of the soybean genome. If a marker is located near a gene, the marker can be used to select for the desired form of the gene. For example, the soybean breeder can use a DNA marker to identify plants that carry the form of the gene that gives resistance to a disease rather than the form that leads to susceptibility. This paper describes the history of the development of DNA markers in soybean and in particular the development of more that 600 simple sequence repeat DNA markers in the Soybean and Alfalfa Research Laboratory at Beltsville, MD. Human geneticists are now heavily involved in the development of the next generation of DNA markers called single nucleotide polymorphisms (SNPs). SNPs are single changes in the DNA "alphabet" from one individual to another. Rapid and inexpensive technologies are being developed to assay for the presence of SNPs. These technologies can readily be adapted for the high throughput screening of SNPs in soybean breeding programs. The creation of a set of SNP markers in soybean will provide a tool that can be used by soybean breeders to identify and select for genes that will produce soybean varieties with improved disease resistance, seed quality, and productivity. Technical Abstract: The objective of this report is to describe the history and current status of DNA marker based genetic linkage maps of soybean and to suggest a direction for future soybean linkage map development. The original maps of soybean were based on RFLP markers. Subsequent maps have included SSR, RAPD, and AFLP markers. The most recent soybean linkage map is based upon n a framework of 600+ SSR markers and contains 20 consensus linkage groups with a total of about 1400 DNA markers. These include RFLP, SSR, RAPD, and AFLP markers along with a number of isozyme and classical loci. In the early 1980's, human linkage map development began with RFLPs and moved to microsatellite or SSR markers. Human geneticists are now heavily involved in the development of single nucleotide polymorphisms (SNPs) to create the "third generation" human linkage map. If soybean and other plant geneticists continue to follow the paradigm of the human genetics community, SNPs will be the next marker technology to pursue. A diversit of technologies have, and are being developed for the parallel discovery and analysis of thousands of SNPs. These technologies are directly applicable to soybean genetics and breeding and specifically to QTL analysis, germplasm characterization, and association analysis. Molecular beacons are suggested as a genetic tool for use in high throughput marker assisted selection based upon SNPs at a relatively small number of loci. |
