Tuesday, November 19, 2013

The Gun(n)s That Transformed Corn

Part II

Our story continues with the development of technology used in corn breeding. Weather conditions and insects continue to challenge farmers as they seek ways to increase corn yield. Researchers are continually looking for ways to grow healthy corn in increased quantities in order to feed a growing world population.


During the 1970s, developments in biotechnology allowed researchers to work directly with genetic material. The gene gun, invented from a collaboration of Cornell University and DuPont between 1983 and 1986, provided a delivery system for DNA into plant cells. The corn plant began to be examined in new ways.

The gene gun uses the method of microprojectile bombardment to add new genetic material to a plant. The process begins by identifying a trait to be added to the corn plant. One trait is the Bt gene to add resistance to the European Corn Borer. The genetic material is isolated from the source and coated onto tungsten particles.

The tungsten particles are placed on one end of a plastic "bullet" (in center dish of picture at left). This "bullet" is then placed in a firing chamber at the top of the machine. When fired, it slams into a stopping plate (in bottom dish in picture) with the tungsten particles going through a hole in the center of the plate and into a petri dish holding receptive corn plant cells.   
The impact from the firing blast causes a doughnut like devastation in the petri dish with the cells in the center being obliterated surrounded by a ring of transformed cells  and little change among the cells at the outermost edge of the petri dish.
The corn plant cells are encouraged to grow on a new medium and are eventually moved to a greenhouse. Use of the gene gun resulted in fertile transgenic plants. During the late 1990s, the gene gun showed a higher success rate over other available gene insertion technologies, making the gene gun the method of choice for many researchers.