Wednesday, November 23, 2016

Ancient Corn Cob, DNA Analyzed

It appears that researchers have sequenced the genome of a corn cob, but not just any corn cob, a 5,310 year old cob. This led to the discovery that maize grown in central Mexico was genetically more similar to maize that is being grown now, rather than it's wild ancestor. They found that the old maize had genetic variants that were in control of making kernels soft which is found as a feature in modern corn. Corn is one of the world's most produced crops, the 5,310 year old cob, also called Tehuacan162, was found in a cave in the Tehuacan Valleys in the 1960's and continues to be one of the oldest known ancient maize specimen in the world.
Nathan Wales who is apart of the Natural History Museum of Denmark said that the DNA within the maize was well preserved even though these old species usually have high levels of bacterial DNA from decomposition. When the genetic testing was done, seventy percent of the DNA of the cob was from the plant. In comparison, there is usually less than 10% of plant DNA found in ancient samples. Paleogenomic techniques were used. DNA was extracted, recovering ultra-short DNA so that they could make the most out of the small maize samples as well as determine the precise age using radiocarbon dating.

There were some similarities and differences between the ancient cob and the maize that is grown today. Although it did not have hard seed coats like its wild ancestor, it was also less than a tenth of the size of the maize grown today. There was also a decrease in the amount of kernels produced
This study can help understand and improve commercially important lines of modern maize. In the future, Wales would like to know how humans dispersed maize, what routes were used and how the maize adapted to diverse environments. I think this research is really awesome, because so much plant DNA was found in the samples and that is very rare. It is also cool to see how maize genetics has changed since the ancient times since it is still a very popular crop that people eat and use daily.

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