Soybean Genome Sequenced

Researchers have sequenced the soybean genome providing them an unprecedented look into how this plant converts four key ingredients - sunlight, water, carbon dioxide and nitrogen - into protein and oil. The research team included 18 federal, state, public and private organizations and they published their findings last week in the journal Nature.

The sequencing is the culmination of more than 15 years of collaborative research. The team used a so-called "whole-genome shotgun" approach to sequence 85% of the 1.1 billion nucleotide base pairs that spell out the plant's entire DNA code. The sequence has value to more than just soybean research too - the data will be a reference in deciphering the genetics of more than 20,000 other legume species.

According to USDA, integrating the new sequence with existing physical and genetic maps of soy will bring researchers closer to linking observable physical traits of the plant to their associated genes and alleles (alternate versions of the genes). The aim is to eventually speed development of new soybean cultivars with higher seed yields, increased protein and oil contents and improved environmental adaptability. They're even working on resistance to such yield-robbers as Asian soybean rust.

This gene sequence is a high quality roadmap. USDA reports that researchers have mapped about 90 important traits affecting soybean growth and development, seed yield, seed protein and oil and disease resistance. The researchers also have access to candidate genes they've never had before. Of course it'll be awhile before the fruits of this work hits the seedbag for your farm, but it's coming.

Evolution of the Soybean. Researchers learn a lot about a plant when they explore its genetic sequence. The recent news of the genome sequence for soybeans has scientists all abuzz, including researchers at the University of North Carolina looking at the evolutionary history of this important oilseed.

Researchers have found evidence of two separate instances, one about 59 million years ago and the other about 13 million years ago when the plant's ancestors doubled their genes by adding an extra copy of the organism's original set of chromosomes - a genetic condition called polyploidy.

Most higher animals and plants (including humans) have two copies of their genetic code in most of their cells through most of their life cycle (they are “diploid”), but polyploid organisms have a extra copies, usually in multiples of two so the material can be evenly divided during sexual reproduction. In each of the polyploid events in the soybean’s evolutionary history, the plant’s ancestor changed from having two copies of its genes to four. After the polyploidy occurred, the new copies either slowly evolved and diverged from the original genes to become new pairs of genes, or the duplicate copy disappeared because it was unnecessary, and the plant eventually became diploid again.

The more recent gene-copying event in the soybean lineage was almost certainly an event known as “allopolyploidy,” where the duplicated set of genes came from a separate organism that was genetically similar, but probably a distinct species from the other genetic donor. In this condition, the new set of genes are essentially still duplicates, but may be somewhat varied in their specific code.

All this adds up to the fact that soybeans are unique. In fact, researchers say that the soybean genome has a unique structural characteristic not seen in a sequenced plant before. The plant doesn't dump duplicated genes like other species do. That first polyploidy event 59 million years ago might be related to the legume's ability to create nodules and fix nitrogen from the air - a big advantage for these plants.

Add it up, and the researchers have plenty more to look at. And as a soybean seed buyer, look for significant trait improvements in the next decade.