Scientific Advance – Sequencing of the Soybean Genome

The sequence and analysis of the soybean genome appear in the January 14 edition of the British journal Nature.  This study makes soybean the first legume species to have a complete draft genome sequence published. The research team involved  are linked to 18 institutions, including Purdue University, the US Department of Energy and the US Department of Agriculture. The US Department of Energy – DOE, the National Science Foundation – NSF, the United State Department of Agriculture – USDA and the United Soybean Board supported the research. The researchers used a Sanger approach to generate sequence covering about 85 percent of the soybeans’s 1.1 billion base genome.  The study opens the doors for further improvements of a crop that has become one of the most important global sources of protein and oil.

Production of a physical map was the first step in sequencing the genome, an intricate task considering the complexities of this legumes´ genetic makeup. These include duplicate copies of genes that account for 70 to 80 percent of the genome’s 46,000 genes, as well as large numbers of transposable elements, which are mobile DNA pieces that may impact gene expression, but are difficult to distinguish from genes. 

A common reality to all important crop species is that their most important production traits, as well as those traits that impact human health, animal nutrition and energy production are quantitatively inherited, or controlled by a large number of genes. The availability of the genomic sequence has the potential to accelerate the study and the understanding of the complex traits in this important crop specie.  Having access to the sequence or using comparative approaches across different genomes may allow cloning and identification of genes as well as development of strategies for the modulation of complex pathways and biological functions.

Therefore, the determination of the soybean genetic code opens to the research community the access to information on thousands of legume genes as well as new possibilities to understand processes that are essential for improvement of soybeans complex agronomic traits like protein and oil content, resistance to pests and diseases, digestibility by animals and humans, among others.  The authors of this study note that “a unique feature of legumes is their ability to establish nitrogen-fixing symbioses with soil bacteria of the family Rhizobiaceae. Information on the nodulation functions of the soybean genome is of particular interest.”  Also, “mining the soybean genome for genes governing metabolic steps in triacylglycerol biosynthesis could prove beneficial in efforts to modify soybean oil composition or content” an area of growing importance considering the interest to increase the use of soybean oil for biodiesel production.

Also, the genome information will allow scientists to compare the large numbers of accessions of soybean in the germoplasm banks to determine which genes are responsible for important traits.  During domestication and selection, many interesting genes and functions may have been discarded.  Now, the new information available and the increasing capacity to screen and study large amounts of genetic resources may lead to discovery of genes of great importance to solve current and future problems in this tremendously important crop.

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