Look Out for Killer Tomatoes! Similarities Between Genetically Engineered and Traditionally Bred Plants

Andrew Cunningham

“Attack of the Killer Tomatoes!” …That’s what opponents to genetically modified organisms (GMOs) think when they hear about genetic manipulation of food crops. GMO food crops are highly controversial because people generally think that they will negatively impact the environment and human health even though no data has been produced to support this claim (Daunert, Deo, and Morin 327). As Botelho and Kurtz explain, this attitude is prevalent because the public gets most of its information on GMO crops from the general media and news outlets that focus primarily on reporting on negative events when covering GMOs. Furthermore, the stranglehold large corporations such as Monsanto have over GMO seeds and Monsanto’s use of aggressive sales strategies does not help the situation as they further degrade the public’s confidence in GMO crops. However, GMO crops are no different than plants that have evolved from the primordial soup or the incredibly colored tulips bred in Holland with which we decorate our houses.

Information on GMO crops abounds and much of it is difficult to understand because it is generally written in a sterile scientific style that reads like a foreign language. However, with a basic understanding of some biological concepts, everyone is capable of analyzing the issue objectively. As Campbell, Reece, and Urry explain, plants and in fact all organisms grow by replicating their cells, and DNA is the recipe used, like a soup recipe that lists its ingredients and how to mix them together to make a certain type of soup. To make tomato soup, the recipe may say to add tomatoes, stock, and spices to a pan and simmer. DNA works similarly. It lists everything needed to create and sustain a cell. In DNA, however, the ingredients and instructions for usage are called genes. A cell reads its DNA recipe and uses the genes needed to produce the cell’s intended function. In scientific lingo, this is called gene expression. For example, the cells in a tomato’s skin will express the gene needed to produce a red pigment, thus making the skin red, while the cells in the stem express the gene that produces a green pigment. Both of these examples are specific traits of a tomato plant just as the skin color of a green tomato is a trait. DNA would of course never define a simmer method such as the one used in cooking. DNA describes more complex processes like enzymes that cause a chemical reaction to produce a certain compound that the plant needs. DNA is similar to a super soup recipe that tells a cook how to produce many different kinds of soups by selecting only certain ingredients and using different cooking techniques to put them all together (Campbell, Reece, and Urry 311).

If a soup recipe is changed, some characteristic of the soup will also change. Say you’re a chef who hates tomatoes and you change the soup recipe to substitute grapes for tomatoes. The resulting soup from this fundamental change will be grape soup. In the same way, DNA can also be changed. A change to a section of DNA is referred to as a gene mutation. Gene mutations can have little effect on cell function or can completely change it (Campbell, Reece, and Urry 344). A mutation in a tomato skin’s gene that causes the cells to produce yellow pigment instead of red does not change the tomato in a deleterious way. On the other hand, a change in the DNA that causes the skin to turn to liquid would be disastrous. The soup would be easier to make as it would not require blending, but harvesting the tomatoes would be a nightmare. Tomato paste would cover everything in sight.

When plants reproduce, they pass on their genes to their progeny as do most living organisms. Half of the genes from the male parent are mixed with half of the genes from a female parent and thus a mixed set are passed down. Scientifically, this is called vertical gene transfer, which is like getting which is like getting two soup recipes, ripping them in half, and then taping one half to each other recipe. Doing this with a soup recipe could easily result in a soup that is not fit for human consumption. Luckily, nature is much more precise when it does its mixing of DNA. Well, nature is precise most of the time. Sometimes it gets the mixing part wrong and fails to split or mix in equal proportions. When this occurs—an event that scientists call disjunction—people manifest diseases like Down’s syndrome (Campbell, Reece, and Urry 258).

This mixing of genes introduces gene variations across a plant population, and this variation is critical to a plant’s survival. It gives future generations new traits which allow them to adapt to slow changes in their environment and to develop resistance to disease. Variation can also be introduced to plants using what is termed “horizontal gene transfer.” Organisms in this case acquire new genes from unrelated species, and then pass them onto their progeny, reminiscent of our beloved tomatoes receiving a gene from a corn plant that alters a tomato’s taste (Campbell, Reece, and Urry 248). (Although if this were to happen, ketchup might need to be renamed “cornup!”)

As P. Gepts describes in the Crop Science journal, plant breeders take advantage of vertical gene transfer mechanisms to introduce gene variation that will enhance their crops (1780). For example, people cross-bred plants to produce pink flowering plants where only plants with red or white flowers previously existed, and breeders can even breed tomatoes that taste better (Giovannoni 2). As Gepts explains, breeders manipulate plants’ genes using their reproduction process to move desirable genes from one plant to another. If a tomato farmer has tomatoes that are continually eaten by pests, the farmer may cross a tomato plant with some type of native tomato plant that the pests dislike in the hope that the domesticated plant picks up the gene for the smell. If it does, he or she can produce seeds from this new hybrid organism and sow his or her fields with pest-resistant tomatoes. This process is called domestication, as the farmer is altering plants to better suit his or her needs (Gepts 1780).

As Mendel found, however, when he experimented with peas in 1890, sometimes the gene intended for transfer doesn’t transfer or it transfers in an unexpected manner (Campbell, Reece, and Urry 294). This problem is termed “gene linkage” and occurs when a gene adjacent to the gene that the farmer desires also transfers to the hybrid plant. In one case, during a cross of a domesticated lima bean plant with a wild lima bean plant, an additional gene transferred from the wild plant to the domestic one. This uninvited gene had been bred out of domesticated lima bean plants because it produces a toxic compound. The cross-breeding exercise reintroduced this undesirable gene (Gepts 1787). Another problem plant breeders face is that many traits are not encoded in a single gene of these linked genes may produce unpredictable results. No data exists to show that this problem has occurred, but hard facts don’t seem to be needed by opponents of GMO crops before they promote panic and misinformation over GMO crops.

Mendel and plant breeders in effect genetically manipulate plants in much the same way that scientists do when they create GMO crops (Daunert, Deo, and Morin 1780). However, rather than cross-breeding two plants and then hoping for the best, scientists use sophisticated methods to extract the exact gene they want and then insert it into a plant cell. Sometimes they extract and inject the gene using a syringe and in other cases they use bacteria to insert the gene into the target cell. The cell then develops into a plant, which, just like in traditional plant breeding, can be used to create seeds so that large crops of identical hybrid plants that have the desirable trait can be produced (Campbell, Reece, and Urry 418). One key difference between plant breeding and GMO techniques is that GMO techniques can add genes to a plant while plant breeders cannot. Plant breeders can only remove or change an existing gene. This is because traditional plant breeders can only transfer genes vertically, while GMO scientists can also horizontally transfer genes (Gepts 1781).

Some people may argue that genes could be changed in a plant through plant breeding to achieve the same result that GMO does by adding a gene. However, doing so would be extremely difficult. For example, if a plant population doe not have a resistance to a particular pest, and a plant breeder wants to change a gene to give the plant resistance, he or she will need to find a plant that has the resistant gene and that can be cross-bred with the domesticated plant. Assuming that a plant can even be found that contains the needed gene, getting that gene to transfer to the domestic population and to produce the required resistance trait is extremely problematic and very imprecise (Gepts 1781). Traditional plant breeding has made amazing advances but still remains a very inefficient method (Giovannoni 2).

If genes can transfer so easily between plants, then why can’t genes from GMO crops transfer to plants in the world, possibly causing deleterious results? As John Burke of the Department of Biological Sciences at Vanderbilt University writes, “Even though no conclusive data has been produced which shows genes have escaped from domesticated crops into the wild, they could” (Burke 1637). This is termed “pollen mediated gene flow,” but no cases have ever been recorded of it occurring between crops red using traditional methods or between GMO crops and wild plants (Gepts 1785). So why haven’t genes escaped and run rampant as a result of plant breeding? Many of the same risks which concern people today with GMO crops probably existed in the early days of crop domestication, but due to the slow pace of plant evolution, detrimental effects either went unnoticed or early plant breeders identified harmful effects and made prudent changes. For example, there is evidence that plant breeding introduced soil erosion problems in pre-Hispanic times. One key lesson from the plant domestication process that occurred over hundreds and possibly thousands of years is that we must monitor and assess every agricultural change on a case-by-case basis no matter what technique is used to introduce it.

The risk of allergic reactions, environmental impact, reduced biodiversity, and transfer of antibiotic-resistant genes to humans are regularly cited by opponents of GMO crops. However, Daunert et al. wrote in a 2008 article that “based on our knowledge of biological mechanisms, there is no known situation where this [accidental gene transfer] to occur or that even if it were to occur, it would have detrimental impacts” (Daunert, Deo, and Morin 327). Thus, most concerns over GMOs are unsupported by scientific evidence and are pure speculation.

The potential of GMO crops is boundless. Agriculture has already become far more efficient as a result of GMO techniques. They have reduced the need for chemical insecticides and fertilizers which have a major negative impact on the environment. Crop production costs have been dramatically reduced due to GMO techniques which help poor countries and rich ones alike to feed growing populations. Statisticians estimate that two billion people will be added to the world’s population by 2050, so to avoid straining our food supply, we will need to embrace technologies like GMOs (Daunert, Deo, and Morin 327).

One challenge to achieving GMO’s full potential is that the seed industry is dominated by a few major biotechnology corporations. Monsanto, for example, produces 90 percent of the world’s GMO seeds. However, even though Monsanto continues to see skyrocketing profits and net sales growth of 30 percent since 2007 to over $11 billion per year, they refuse to adjust seed prices to assist poor companies (Marie-Monique 310). In some cases, this has resulted in extreme hardship such as farmer suicides in India because farmers must place themselves into heavy debt to purchase GMO seeds (Heeter). Control of GMO research and production must become more distributed if everyone is to benefit from its potential (Daunert, Deo, and Morin 328). We need to slice up the GMO tomato and make sure that many responsible corporations and organizations all get a piece.

If we refer to genetic modification in a lab as enhanced breeding, then we may be able to calm down the masses that fear killer tomatoes. However, no one can or should dismiss the risks of genetically modifying food crops in a lab; we just need to learn from the evolution of plant-breeding and ensure that no killer tomato genes are given an opportunity to escape from a lab. Through GMOs, we may be able to create a tomato plant plentiful enough to feed an entire town that costs pennies to grow and that is distributed fairly.

Works Cited

Botelho, David, and Hilda Kurtz. “The Introduction of Genetically Modified Food in the United States and the United Kingdom : A News Analysis.” Social Science Journal (2008): 13-27. Print.

Burke, John M. “When Good Plants Go Bad.” Evolution (2004): 1637-1638. Print.

Campbell, Neil A, Jane B Reece, and Lisa A Urry. Biology, Eighth Ed. San Francisco: Benjamin Cummings, 2008. Print.

Daunert, Sylvia, et al. “The Genetically Modified Foods Debate: Demystifying the Controversy Through Analytical Chemistry.” Analytical & Bioanalytical Chemistry (2008): 327-331. Print.

Gepts, P. “A Comparison between Crop Domestication, Classical Plant Breeding, and Genetic Engineering.” Crop Science (2002): 1780-1788. Print.

Giovannoni, James. “Breeding New Life Into Plant Metabolisms.” Nature Biotechnology (2006): 2. Print.

Marie-Monique, Robin. The World According to Monsanto. New York: The New Press, 2010. Print.

Seeds of Suicide. Dir. Chad Heeter. Perf. Chad Heeter. Frontline: World Rough Cut. WGBH Educational Foundation, 26 July 2005. Web. 22 Nov. 2010.

Instructor’s Memo

My fall freshman composition class had as its theme food and our relationship to it—emotionally, physically, and culturally. Each sequence confronted this topic from a different angle and examined and challenged how we think about food and how we confront topics related to it through writing, investigation, and research. For the critical project, many of my students chose to discuss various contemporary and often heated topics surrounding food, such as pesticides, the rise of the organic market, eating disorders, and—as is the case with Andrew—genetically modified crops. While several students chose this same topic, Andrew was the only student bold enough to take the unpopular position of supporting genetically modified plants, and in his essay, “Look Out for Killer Tomatoes!: Similarities Between Genetically Engineered and Traditionally Bred Plants,” Andrew defends his stance deftly. He tackles this very controversial topic by first addressing and confronting the mental image of genetically modified food and then breaking down these preconceived notions through logical reasoning, scientific data, and expert rhetoric. What I admire most about this essay is how much of his own voice Andrew is able to retain within the critical sphere and how his sense of humor breaks through in an oftentimes humorless genre. In this vein, Andrew uses the recurring image of “killer tomatoes” throughout this essay, expertly weaving the various facets and avenues his paper takes into a cohesive whole. Another aspect of Andrew’s paper that I find impressive is the way he taps into the language of scientists, acquainting us with their terminology and processes. He breaks down the complexities of cross-breeding to make it not only readable but enjoyable to read as well.

— Jacques Rancourt

Writer’s Memo

I chose to research genetically modified organisms (GMO) because I feel this technology has the potential to help address hunger in developing countries and that the majority of people distrust GMOs purely because they misunderstand the technology. As I researched the subject I found both of these assumptions to be true, but at the same time I learned that the technology is not completely risk-free. This discovery caused me to rethink how I evaluate an issue and taught me to always research a subject in depth using objective sources before making any judgments.

When writing papers I always try to insert some humor as I feel including it makes the paper more enjoyable to read and thus, is more likely to be read. Furthermore, using humor helps me to enjoy the writing process and I feel as a result improves the quality of my writing. This approach does mean that corny lines sneak into my initial drafts and are removed along the way when I work out that they are really only humorous to me. I hope that my use of the movie “attack of the killer tomatoes” to insert humor enhances my paper and does not distract people from the points which I was trying to make.

— Andrew Cunningham

Student Writing Award: Critical/Analytical Essay