Genetically Modified Corn

Adam Sammons

Genetically modified crops have caused a great debate. Some people vigorously disapprove, while others sing their praises. Genetically modified (GM) crops can also be called transgenic crops, or genetically modified organisms (GMOs). Rather than a plant acquiring genes through natural pollination, this new breed of genetically engineered crops contains genes that have been randomly spliced into them by scientists. The inserted gene sequence is called the transgene. Transgenes can come from other plants, or astoundingly they may even come from completely different organisms. For example, Bt corn contains a bacterium gene that helps it to produce its own insecticide which in turn helps out the environment by decreasing the amount of pesticide that would normally be applied to protect the crop. Transgenes can be used for many purposes such as disease resistance, pest resistance, increased tolerance to hot and/or cold temperatures and even withstanding drought conditions. In a way GM crops are undergoing the process of natural selection that crops have always endured, however, scientists are greatly accelerating the rate at which this would naturally occur. Here is a picture from the USDA that shows insect infestation in two naturally grown cotton plants (on the left), compared to genetically modified cotton (on the right).

To see a simulation of how transgenic plants are made go to http://www.colostate.edu/programs/lifesciences/TransgenicCrops/animation.html.

The United States Department of Agriculture, Environmental Protection Agency, and the Food and Drug Administration are largely responsible for overseeing GM crops. The USDA evaluates the plants to see if they will have a negative effect. Negative effects are things such as harming people, or animals, or spreading genes that could create plant viruses. The FDA evaluates if it is safe as a food or food ingredient, and the product’s nutritional information, as well as if it causes allergic reactions. The EPA oversees plants engineered to have pest resistance such as Bt corn. Bt corn contains a soil bacterium gene Bacillus thuringiensis. This soil bacterium produces spores that have a crystalline protein. When digested by insects this bacterium breaks down to produce a toxin called delta-endotoxin. Delta-endotoxin creates holes in the insects’ intestine, which breaks down the digestive system and causes the insect to die in several days. Obviously this helps the crop because the insect can no longer feed on it. Here is a picture from google of Bt corn (notice the lack of insect infestation).

Another type of GM corn is helping to wage the war against pests. This corn is resistant to corn rootworm which targets the roots of young seedlings. This causes the plant to grow a lot slower, and in some cases the corn is so damaged that it cannot grow upright. Here is a picture from the USDA of corn that has been damaged by corn rootworms.

From left to right are varying levels of damage from the corn rootworm with the worst damage on the left, and a healthy non-damaged plant on the far right. As you can see, corn rootworms are capable of severe damage to the corn plants, and GM corn helps to greatly reduce these pests. Rootworm resistant corn works in the same way that Bt corn works. Basically, any rootworm that eats this corn will be killed by an intestinally induced toxin. Another advantage of using GM corn to control corn rootworms is that either no or very little pesticide is required. This greatly helps to reduce the amount of pesticide entering our environment because previously large amounts of pesticide were sprayed on the roots (or soil), which easily leached into and contaminated our water. Since GM corn requires less pesticide application, it will help protect our water and environment.

Many people have fears that genetically modified corn is not safe. According to the USDA,

“South Dakota State scientists have fed genetically modified soybeans and corn to several generations of pregnant laboratory mice and found no ill effects. Purdue researchers evaluating milk from cows fed genetically modified corn found no difference in the milk produced. There also were no differences in milk composition, production or feed intake between the cows fed modified corn and the conventional corn-fed control group. Kentucky scientists conducting similar tests on pigs fed genetically modified soybeans found the meat did not contain either the modified genes or the proteins. Maryland researchers have found no major effects on non-target insects in a field-sized research study of modified corn” (Gene Dreams are now Reality).

In light of all of this evidence, I would have to say that GM corn is safe. GM corn has no bad effect on animal’s babies, milk, or even their meat. It also does not greatly affect non-target insects. I think that GM crops will be the future of agriculture as the worlds population continues to grow while it’s available land for agriculture declines.

There are many GM products already in the works for the future. Plants such as tomatoes will be genetically modified so that they can grow in salty soils. The nutritional content of canola oil will be improved. Grass will grow slower (so that you don’t have to mow it as much) and it will be more resistant to cold, heat, and drought conditions. Grape vines will be able to resist diseases, and trees will be unsusceptible to insects and herbicides. There are many more GM products in the works for the future. The only limit seems to be scientists so far. It is easy to see how GM plants will be greatly beneficial to us in our future.

All is not perfect in the world of transgenic crops. There are many questions and potential problems that have yet to be answered. One problem is the possible allergens that GM products might cause in certain people. Another is the butterfly. Many environmentalists are worried that butterflies will be killed by pest resistant GM crops. However, a study conducted by the USDA found that Bt corn did not affect butterflies. Yet another problem is possible crop-weed gene flow and crop-crop gene flow. Weeds could get genes of herbicide resistant plants, and thus they could become herbicide resistant. Many third world countries such as Zaire who are starving refuse GM crops because they don’t want the genes even entering their country (this is a pretty strong stand against GM crops since over half of their population is starving and they still refuse them)! “Activists in India have set fire to fields of crops suspected of being used for testing” (Mercola).

Mexico and the United States have been battling over GM corn. Mexico does not allow GM corn to be grown in their country; however scientists have found genetically modified DNA in the wild maize that Mexico so proudly loves (Mercola). This GM corn in Mexico is being naturally spread by cross-pollination (Kaufman). Genetically altered genes from crops grown in America and Canada are finding their way into Mexico’s wild maize crop. “Up to 70 percent of wild Mexican maize now carries transgenes that could only have come from genetically engineered crops” (Mercola). This is extremely unfair to Mexico since they have banned GM corn from being grown in their country, yet these genes have found their way into Mexico’s corn. Who is responsible for this gene flow? Is it the manufacturers of the GM crops, or the farmers who grow them in their fields? How would a lawsuit by Mexico likely be settled? It is basically impossible for Mexico to get rid of these unwanted genes that their corn has acquired. In Oaxaca Mexico, where corn was domesticated, corn is very diverse. Commercial growers come here each year to look for wild corn that might be beneficial to them. However, now most of this wild corn contains non-wild genetically altered genes. Who’s to blame and how can it be fixed? I don’t think anyone truly knows.

In conclusion, it is easy to see the pros and cons of genetically modified corn. This debate will likely go on for decades without being resolved. As with any issue there are both positive and negative impacts. Most of the negative impacts of GM corn remain unknown. Questions such as how will this affect other crops and weeds remain unanswered. I hope that you have learned a lot more about genetically modified crops then before you read this paper. I hope that this paper has only peaked your interest, because this is a hot topic and will surely be an interesting current event to follow. I think that further testing needs to be done on GM crops before they are allowed to be grown in the wild, because once these genes get out there, it is impossible to recall them, and no one yet knows their long term impact on other crops, weeds, and the environment.

Sources

www.usda.gov (on 4/29/05).

http://www.colostate.edu/programs/lifesciences/TransgenicCrops/what.html (on 4/29/05).

Kaufman, Marc. U.S. Genetically Modified Corn is Assailed. The Washington Post. A02. November 10, 2004.

Gene Dreams are Now Reality. <www.usda.gov> (on 4/29/05).

Mercola, Joseph. “Genetically Modified Corn Spreading to Protected Wild Corn.” Nature. V. 414. P. 541-543. November 29, 2001.

Mercola, Joseph. “Health Risks of Genetically Modified Foods.” The Lancet. V. 353. May 29, 1999.

Orue, Martin and O’Donnell, Susana and Arino, Anthony, and Netherwood, Joaquin and Gilbert, Trudy and Mathers, Harry. “Degradation of transgenic DNA from genetically modified soya and maize in human intestinal simulations.” The British Journal of Nutrition. V. 87. I. 6. P. 533-542. June 2002.