Friday, January 29, 2016

Species Spotlight: Soybean

Until I started studying soybean for my PhD, I only ever associated them with the fields lining the highways of the Midwest and delicious edamame.

But soybean is important for a lot more than just food. Today let's take a closer look at the species I'm currently studying.

Soybean's scientific name is Glycine max. It originates from China and has been a successful agricultural crop in many countries. In the United States in 2012, soybean was the second most valuable crop right behind corn! There are dozens and dozens of cultivars and these are sorted into maturity groups. Maturity groups are based on the changes in day length required to produce flowering in soybean and thus are related to the latitude in which the soybeans are best suited to grow.

Beyond its uses for food, soybean is incredibly important in many other industries, including biofuel, crayons, paint, wax, clothing, elevator oil, the list goes on. In fact the average soybean acre produces 44 bushels which can be used to create 8gal oil, 2500gal soymilk, 320,000oz tofu (640,000g protein), 66gal biodiesel or 82,368 crayons!
Indiana State Fair homage to soybean. Personal photograph
Another reason soybean is a popular crop is nodulation. Nodulation is the process by which specific bacteria colonizes the roots. During this colonization process, a nodule (they look like bubble protrusions) is grown from the roots which becomes bacteria new home. These bacteria fix nitrogen that is biologically unusable into biologically useable versions of nitrogen. This available nitrogen is used by the soybean and also replenishes the soil. Because soybean replaces nitrogen into the ground, it is very useful for renovating a field after a nitrogen consumer crop, such as corn. This is why when you drive down the road in the Midwest you often see a field of corn one season and a field of soybean the next.


Another type of soybean I work with is Glycine soja, which is thought to be the closest non-domesticated ancestor of the current soybean we all know and love. The importance of non-domesticated ancestors in research cannot be understated. Domestication drastically changes the species genotype and phenotype, often limiting them to very narrow results. As you can see in the image below, soybean has been bred to produce thicker stems and more vegetative tissue which leads to greater yield. While all of these are good traits, during this process other traits may have been lost. For example, non-domesticated soybean (G. soja) has been shown to be more tolerant to dehydration stress than domesticated soybean (G. max Chen et al, 2006). That is why we are studying both domesticated (G. max) and non-domesticated (G. soja) soybean side by side. Maybe we can isolate a trait to potentially breed back into domesticated soybean!

Glycine max (left) and Glycine soja (right). Personal photograph.


There we have a brief rundown on the value and awesomness of the soybean! For more information about the agricultural side of soybean, I highly recommend this book: Coolbean the Soybean. It is full of facts and geared for a grade school-middle school level. Their webpage also has some fun activities for kids.

References:
http://genezoo.missouri.edu/soybean.cfm
http://corn.agronomy.wisc.edu/Crops/Soybean/L004.aspx
http://ncsoy.org/media-resources/uses-of-soybeans/
http://agron-www.agron.iastate.edu/Courses/agron212/Readings/Soy_history.htm
http://www.agcensus.usda.gov/Publications/2012/
Chen Y, Chen P, de los Reyes BG (2006) Differential response of the cultivated and wild species of soybean to dehydration stress. Crop Science 46 (5):2041-2046 doi:10.2135/cropsci2005.12.0466 

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