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Genetic modification has made its way into most people’s lives, whether it be through trying to find non-GMO foods at the grocery store or through news of complex, potentially life-saving methods such as CRISPR. Researchers at NC State would like to further this impact by improving one of the United States’ major exports: cotton.
Vasu Kuraparthy, a crop science professor, and Ryan Andres, a former grad student studying crop science, have developed a line of cotton plants that are more disease resistant and sustainable than regular lines. The secret to this lies in the leaves of the cotton plant, which greatly impact the plant’s susceptibility to disease. According to the study, the “okra” leaf shape, which is spread out and slender compared to the normal cotton leaf shape, creates a less humid environment for the cotton, which leads to a lower susceptibility to boll rot. Since the leaf shape has a lower surface area, it also requires less pesticides to grow.
“If you have varieties [of cotton] with the okra leaf shape, it is open, the lobing is less, it allows more aeration to pass through, and whatever light is available, it will let the light pass through,” Kuraparthy said. “Thereby, it creates a microclimate that is less humid and more dry.”
In order to successfully replace the normal gene for leaf shape in cotton with an okra leaf shape, Kuraparthy and Andres first mapped the area of the cotton genome that coded for leaf shape. Kuraparthy described this process as being similar to finding a city through a highway system.
“On Highway 70, if you look at exit 252, you can see that Highway 70 goes through Missouri, and near exit number so and so is Joplin, Missouri,” Kuraparthy said. “Exit numbers are like DNA markers. Using DNA markers, [Andres] mapped where in between these two markers —‘two exits,’ this ‘gene’ is located, or Joplin.”
Andres proceeded to use more complex methods to figure out which genes coded for which proteins. This would later assist the team in a method called virus-induced gene silencing, which uses a virus with the desired genes implanted in it to trick the plant into silencing its own gene, along with the gene that is in the virus.
“Basically, we just amplified and sequenced only the specific region, based off the markers,” Andres said. “They’re kind of like gel electrophoresis — it’s called capillary gel electrophoresis.”
Although the okra leaf has many benefits, one of its drawbacks includes a lower rate of photosynthesis due to its lower surface area. Another issue with these findings is that the okra leaf genetic modification is not heritable. Kuraparthy is continuing his research and trying to develop a spray that triggers okra leaf genes activation. An alternate solution would be to produce a plant that has normal leaves while it is growing, which then changes to an okra leaf shape.
“What we want is a variety that has this leaf shape in the beginning,” Kuraparthy said, referring to the normal cotton leaf shape. “For at least two months, when the flowering happens in cotton, and then changes the leaf shape to okra, so you have both leaf shapes in a single plant.
Kuraparthy hopes that the modified cotton plant will give the Southeast a competitive edge in exports over other major cotton producers. Along with its economic benefits, the plant will also help reduce pesticide and chemical usage and lead to a larger harvest, leading to more sustainable farming practices. As for now, Kuraparthy continues his research to put this discovery into practice.
“Ultimately, our aim is to make cotton more efficient, have higher productivity and be good for the environment; the cotton cultivation will have less of a negative impact on the environment, and also keep our U.S. cotton growers more economically viable,” Kuraparthy said. “So that’s our aim of this project in the long term.”