|CREGAN, PERRY - Retired ARS Employee|
Submitted to: The Soybean Genome
Publication Type: Book / Chapter
Publication Acceptance Date: 2/1/2016
Publication Date: N/A
Interpretive Summary: Classical genetic maps indicate the relative positions of genes that control readily observable traits such as plant structure, maturity, flower color, disease and insect resistance and various chemical characteristics. Molecular genetic maps contain DNA markers that are used to define the positions of genes that control various traits of interest and of economic value. Classical genetic maps contain relatively few genetic markers whereas molecular genetic maps often contain many thousands of DNA markers and are therefore very useful in defining the positions of gene controlling traits including resistance to disease and insects, protein and oil quantity and quality in the seed and traits associated with productivity. In this review paper a description is given of the origins of soybean classical and molecular genetic maps and the research that combined the classical and molecular genetic maps. In the case of the molecular maps, the various types of DNA markers that were used over the years to improve the molecular maps are described. The first soybean molecular genetic map was developed in the late 1980’s and released in 1990 and contained 150 DNA markers. The current map contains more than 21,000 DNA markers that can be rapidly analyzed with high throughput technologies. This information will be of use to soybean geneticists and breeders who use or would like to use DNA markers in their genetic studies.
Technical Abstract: A brief history of classical genetic mapping in soybean [Glycine max (L.) Merr.] is described. Detailed descriptions are given of the development of molecular genetic linkage maps based upon various types of DNA markers Like many plant and animal species, the first molecular map of soybean was based on restriction fragment length polymorphism (RFLP) markers. Because of the relatively low level of sequence diversity in soybean, the first RFLP maps were constructed in populations derived from crosses of cultivated (G. max) x wild soybean [G. soja (Seib. et Zucc.)]. Random amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) loci were briefly used in map construction, but soybean was the first plant species in which simple sequence repeat (SSR) markers were employed and SSRs soon became the marker of choice in map development. During the development of RFLP and SSR genetic maps the classical genetic linkage groups were associated with the molecular marker based linkage groups. Ultimately, single nucleotide polymorphism (SNP) became the most widely used marker type. The most recent molecular genetic map of soybean incorporates more than 21,000 SNP markers positioned on the 20 pairs of soybean chromosomes. This map provides an excellent source of DNA markers data and was used to update the soybean genome sequence assembly (http://www.phytozome.org/) which was initially based on a soybean molecular genetic map with only 5,000 genetic markers.