Genetically Engineered Crops and Their Environmental Impact

Nathan Griffith

Genetically engineered crops began showing up about a decade ago when biotech companies began commercializing them. The crops, mainly corn, cotton, and soybeans, were altered mainly to lower their susceptibility to weeds and pests. Recently, a new generation of genetically altered crops were developed. These plants, primarily corn, were specifically engineered to produce chemicals for industrial and research use and pharmaceuticals.

With all of this engineering and modifying going on with these crops, there are concerns over the effects of these new technologies. One of the main concerns is over their potential effects to the environment. This concern comes in several different areas, including concerns over weeds, concerns over pesticides, and concerns over viruses introduced into the genomes of the crops.

One of the areas of concern of this technology in regards to the environment is that of the genetically modified plants becoming weeds, the term weed referring to any type of plant growing in an area where humans don’t want them. Weeds are responsible for affecting the crop yield in the agriculture for a particular area. If left unchecked in an unmanaged environment, these weeds can upset the ecosystem.

One concern in this area is that these genetically engineered plants may be able to grow in places they aren’t otherwise able to grow in, thus becoming a nuisance in those areas. One example of this would be genetically altered rice plants engineered to be salt-tolerant taking over nearby marine estuaries after escaping cultivation.

Another concern in this area deals with whether or not genes introduced in genetically altered crops that might transfer to nearby relatives of the crop via their pollen. This might enable weedy relatives of the engineered plant to grow in areas it wouldn’t normally be supported.

Another area of concern with this new technology deals with pesticides. Insects contain genes that make them susceptible to certain types of chemicals for example Bacillus thuringiensis, or the Bt toxin. Crops are being engineered to naturally produce these chemicals in their tissue to make them less susceptible to these pests. However, the concern with this is that through having these pesticides to naturally occur in this plant, you are effectively weeding out those insects that are susceptible to chemicals like the Bt toxin. If you have a mutation in the insect population that allows a immunity to any of these chemicals, the chemicals will become effectively useless.

The last area of concern discussed here deals with viruses that are introduced into a certain crop’s genome. One of the more ubiquitous uses of genetic modifications of these crops is creating new crops that are resistant to viruses. These are created by engineering parts of the crop’s genome with viral parts. It is unclear why, but this allows plants to be immune to these viruses. The risk here is that these plants may be able to create new viruses that are worse than their predecessors. This can happen through two processes, transcapsidation and recombination.

Involved in the process of transcapsidation is the encasing of genetic material of one virus by the plant-produced viral proteins. This, in effect, creates hybrid viruses that could transfer viral genetic information to a new host of plants it couldn’t originally infect. Rarely do these viruses ever make it past the first generation of hybrid, seeing as how the viral genetic material contains no genes for the foreign proteins it gained from the plant.

Recombination is a process that occurs between the viral genes the plant produces and closely related genes of incoming viruses. This may result in the creation of new viruses that are worse than the parent generation in that they are able to affect a wider spectrum of hosts or are more virulent than the viruses that came before them.

These three areas of concern are taken into account whenever these modifications are made to these crops. However, when letting these crops loose into a system as complex like our environment, it’s hard to say what exactly will happen. In some cases, everything will work out perfectly. In others, one small factor, one small change in the genetic makeup of these crops may have the potential to prove harmful to our environment.

As a student pursuing a degree in Civil Engineering, and as my interests are wandering more toward the environmental side of Civil Engineering, I realize that these concerns over how genetically engineered crops affect the environment may in the future provide challenges in a job situation in which I am working as an Environmental Engineer.

Sources:
“Risks of Genetic Engineering.” Union of Concerned Scientists. 2002. 2 December 2004. This is a very informative website from the Union of Concerned Scientists. It provides a very good overview on the different risks genetic engineering poses to our environment.