Root-ing for a good harvest
On June 13, 2017, the MU Drought Team had their first harvest of the summer at Bradford Research Center. A 17-person team, organized by graduate student Shannon King, helped dig up and remove hundreds of roots from the field, preserve them in liquid nitrogen, and send the samples to the lab for future experiments. King’s specialty is field biochemistry, so her role is to make sure everything runs smoothly in the field.
The first step of the process was to remove the plants from the ground. Two “diggers” spent the day carefully avoiding root tips with their shovels as they removed the corn plants from the ground. If the root tips were severed, the plant would be useless, because the tip of the root is what is removed from the plant and taken back to the lab for research. Once dug up, the “runners” sprinted across the field to take the plants – soil and all – to the cutting stations, where the roots will be cut up and placed in test tubes.
Graduate student Tyler McCubbin and post-doctoral researcher Laura Greeley removed the soil from the roots and identified the Node 2 roots of the plant, which were buried under the soil. The Node 2 roots are important because as the second level of roots up the stem, they are the only roots the MU Drought Team can look at both in the field and in the lab. The Node 1 roots break in the soil and space in the lab limits the team from looking at anything past the Node 2 roots.
Once McCubbin and Greeley identified the root tip and removed them from the plant, the “slicer” cut the root into different sections to investigate how different parts of the root grew and responded to stress. Each root tip was sliced into tiny 3mm sections, a little thicker than a nickel, and put into a tube with a label that corresponded with the part of the field it came from. Parts of the field were watered differently, so by labeling the plants by which part of the field they grew in, the team was able to compare the root growth to the amount of water it received back in the lab.
Each sample is deposited in liquid nitrogen, which freezes the plant and stops all growth in order to preserve it for the lab. Nothing can grow at 200 degrees Celsius, the temperature of liquid nitrogen, because the water expands and breaks down the cells. There were over 200 plants in the entire field, so the harvesting process was repeated for almost seven hours until all the plants had been extracted and properly stored. Even with 17 people, it was a long process to remove all the plants from such a large field.
Although the main purpose of the harvest was to gather data from the Node 2 roots, the second level of roots before the stem of the corn plant, samples were also taken from the leaves and soil to get an understanding of the whole plant. It is important for the MU Drought Team to have context to what is happening in the field and how that is affecting the rest of the plant. The water potential of each sample, or how water stressed the plant is, was measured as well, and the nutrient level of the soil was tested throughout the field. Although the amount of samples gathered should be more than enough for research purposes, the MU Drought Team replanted another batch on June 28, 2017.