Political Ecology of GMOs

A Middlebury blog

The Problems with Gene Flow in Genetically Modified Organisms

Jessie Ralph

 Positionality Statement:

I am a first year undergraduate student at Middlebury College majoring in Environmental Studies with a focus in Economics. While I attempt to provide a more scientific view of gene flow by looking at case studies and facts, I am concerned with the environmental nature of gene flow out of genetically modified crops. My interests in the environment as well as my upbringing in a community that was relatively conscious of food safety and health has definitely impacted the way that I view genetically modified organisms. From an early age I have been exposed to documentaries about the benefits of organic food and some of the downsides of large commercial farming. My upbringing in this environment has definitely encouraged me to focus more on the downsides of biotechnology in this paper. However, my courses at Middlebury have encouraged me to view these issues that I address through various lenses. My positionality may be reflected in my writing.


The introduction of new technologies in communications, transportation, and biotechnology among others over the past few decades has transformed the lives of nearly all of Earth’s inhabitants whether directly or indirectly. One of these innovations, the genetic modification of organisms, has revolutionized the way the world looks at agriculture and has redefined the relationships between global economies, environments, and politics. A genetically modified organism (GMO) is an organism whose “genetic material has been changed in such a way that does not occur under natural conditions through cross-breeding or natural recombination” (“Genetically Modified Organism (GMO),” n.d.). Gene flow permits the movement of genetic material between individuals and when incorporated to the larger debate surrounding the safety of genetically modified organisms, gene flow leads to increased complexity. Through this paper, I illustrate the relationship between the effects of gene flow of genes from GMOs on the environment and the social and political factors that allow this genetic drift to occur.

The Basics of Gene Flow:

Gene flow, according to Bao-Rong Lu, is “a natural process that contributes to species evolution” (Lu, 2008, p. 73). It is important to keep in mind that gene flow is a crucial natural process that allows for the proliferation of beneficial traits in plants. However, as Lu also points out, gene flow out of genetically modified (GM) crops “could have adverse environmental, socio-economic, or ethical impacts” (Lu, 2008, p. 73). Understanding the process of gene flow assists in comprehending the concerns for potential adverse outcomes. In gene flow, genetic material, such as genes, are transferred between individuals (Lu, 2008, p. 74). Two types of gene flow exist: horizontal gene flow, when genes are transferred by processes other than reproduction between unrelated species, and vertical gene flow, which is the transfer of genetic materials between different populations of a species through reproductive processes (Lu, 2008, p. 74). While the focus on the dangers of gene flow in this paper relies on the process of vertical gene flow, it is also important to note that horizontal gene flow has allowed for the production of GMOs in the first place (Kameswara Rao, 2008). Bao-Rong Lu also describes some of the processes through which gene flow occurs in plants: pollen-mediated gene flow, seed-mediated gene flow, vegetative-propagule-mediated gene flow (Lu, 2008, p. 75). Pollen-mediated gene flow is the transfer of genes from one plant to another through traveling pollen, allowing these genes to infiltrate either the same population from where the pollen originated or different populations (Lu, 2008, p. 75-6). Seed-mediated gene flow allows for the spread of genes through plant seeds carried away by the elements and animals (Lu, 2008, p. 76). Finally, in vegetative-propagule-mediated gene flow, genetic material is transported through “vegetative organs” of plants by various elements and animals (Lu, 2008, p. 76). Figure 1 provides a diagram of gene flow.

Figure 1. Basics of gene flow (Lu, 2008).


Gene Flow in Genetically Modified Plants:

In addition to the basics of gene flow, GM crops add new ways through which the transfer of genetic material can occur. Lu describes the three different types of gene flow out of GM crops: crop-to-crop transgene flow, crop-to-weedy transgene flow, and crop-to-wild transgene flow (Lu, 2008, p. 78). Crop-to-crop transgene flow is the transfer of genetic material from GM crops to the same type of crop that has not been genetically modified (Lu, 2008, p. 78). Crop-to-weedy transgene flow is the movement of GM genes to weeds. Lastly, crop-to-wild transgene flow is the flow of gene from a GM crop to a wild species (Lu, 2008, p. 78). However, only pollen-mediated gene flow allows for hybridization between GM crops and other plants (Lu, 2008, 78). While gene flow is a crucial biological process and can be very helpful to propagate beneficial genes and traits to a species, it also poses a threat to plants species for the same reasons. As Lu demonstrates through the examples of various kinds of gene flow related to transgenic species, it is easy for genes to move from population to population of closely related species. This could also pose a threat to biodiversity of crop and wild species in the future as I will go into further detail about later in the paper (Lu, 2008, p. 86). Figure 2 provides a diagram of gene flow in GMOs.

Figure 2. Gene flow in a GMO (Lu, 2008).


Gene Flow and Politics:

As genetically modified organisms have come to play a larger role in global agriculture, gene flow has become highly politicized because of the intellectual property as well as socio-economic value that these seeds now contain. According to Glenn Davis Stone, prior to the 1980 Chakrabarty Supreme Court decision, no life forms had been patented (Stone, 2010, p. 5). This Supreme Court case extended the limitations of patent laws to include a bacterium as it had been genetically modified, transforming the organism into a person’s or corporation’s intellectual property (Stone, 2010, p. 5). Eventually, these laws applied to include plants. Stone continues to include the Bayh-Dole legislation of 1980 as well, which permitted the sale of the results of publicly funded research to private buyers (Stone, 2010, p. 5). Now, private seed companies such as Monsanto can apply for the rights to organisms that have been genetically modified. Patent laws and intellectual property rights have led to a multitude of legal battles between farmers and seed companies regarding the rights to use genetically modified seeds. Monsanto addresses the issues of patent infringement on its website (“Saved Seed and Farmer,” n.d.). The website states that seed saving, when farmers do not buy new seeds from Monsanto each year and use seeds from their harvests, qualifies as patent infringement (“Saved Seed and Farmer,” n.d.). These accusations of seed saving, or the growing of patented plants without a license, have become far more complex as a result of gene flow. On the International Property Watch website, one article discusses organic farmers suing Monsanto because of “contamination” of crops by genetically modified organisms (Saez, 2011). The lawsuit addresses whether or not organic farmers can be accused of patent infringement when gene flow occurs (Saez, 2011). As Bao-Rong Lu described in his paper, gene flow from genetically modified crops to conventional crops is a possibility, and now this natural process could be problematic for farmers, conventional crops, and wild plants alike.

Gene Flow and Agriculture:

As a result of the extension of patent laws to living organisms, gene flow now plays an increasingly significiant role in the agricultural industry as a result of the introduction of GM genes. I am not trying to demonstrate through this paper that gene flow or patent laws are inherently negative, but I aim to exhibit through case studies the complications that can result from a combination of human technology and natural biological processes.

In Mexico, the production of maize has played an important part in the history of the native peoples where growing maize has cultural significance (McAfee, 2008, p. 149). In her journal article, McAfee addresses the concerns that farmers and geneticists have for the local varieties of maize incorporated in these farming traditions if gene flow occurs from GM maize (McAfee, 2008, p. 151). McAfee states in her paper “plant geneticists worry that transgene constructs transferred to local maize varieties or teosinte might confer survival advantages to the resulting hybrids, enabling them to out-compete other maize strains and thus accelerate the loss of useful traits” (McAfee, 2008, p. 151). Gene flow also leads to legal concerns and expensive lawsuits for farmers because of patent laws. In the 2008 documentary “Food, Inc.” one farmer explains he can be held accountable if pollen or seeds of GM crops infiltrate his fields. This puts his livelihood in danger as his neighbors grow GM crops (Kenner, 2008, 7). While the makers of this film may be positioned against large agricultural firms such as seed corporations like Monsanto, the interview with this particular farmer provides insight to the threat gene flow poses to conventional farmers. As these instances demonstrate, this natural process of gene flow becomes largely complicated with GM crops involved.

Gene Flow and the Environment:

For many the largest threats that gene flow poses are to conventional and wild varieties of certain plant species. According to the website “GMO Compass” some research constantly analyzes if interbreeding between cultivated genetically modified plants and wild plants could be detrimental to the environment (“Out-crossing and Gene Flow,” 2006). This site explains that environmental damage could result if the modified genes put some plants at an advantage (“Out-crossing and Gene Flow,” 2006). The potential dangers posed by certain genetically engineered varieties are also listed. However, this site provides a limited perspective as it focuses on GM crop threats in Europe. Crops like maize have no wild relatives in Europe, but plants like rapeseed have potential to hybridize with native plant species as well as create herbicide tolerant weeds (“Which Crops Could Spread,” 2006). An article by Yann Devos et al. further displays concerns over gene flow of herbicide tolerant oilseed rape or rapeseed in Europe, and discusses that “the incorporation of a HT trait(s) may increase the fitness of recipient plants, making them more abundant and persistent, and may result in weeds that are difficult to control by the herbicides to which they are tolerant” (Devos et al., 2004, 135). Scientists studying the Hawaiian Islands also fear hybridization between GM plants and native, wild plant species, many of which are rare. If anything, these concerns are much greater because “insular species are more prone to interbreeding because they tend to be less genetically divergent and to have weaker crossing barriers than their continental counterparts” (Münster & Wieczorek, 2007, p. 2). The authors here emphasize, as I have, that gene flow is a completely natural process and occurs regardless of whether GM genetic material is involved (Münster & Wieczorek, 2007, p. 2). Although a natural process, gene flow poses certain threats when involving transgenic and wild varieties of plants. As the case studies and evidence suggest, it is crucial that the potential environmental impacts of transgenic gene flow are understood prior to the cultivation of a GM crop variety.


Through this paper, I tried to address some of the ways through which a natural process, gene flow, and human generated varieties of plants could create such a complex social, political, economical, and environmental dynamic when interacting with each other. The evidence demonstrates that there are many different ways to look at one specific issue involving the genetic modification of plant seeds, but that the issue lies in nature’s application of a crucial biological process to a manmade organism. The variety of perspectives in further research done on the subject highlights the complexity of gene flow out of genetically modified organisms.


References Cited:

Devos, Y., Reheul, D., Schrijver, A. D., Cors, F., & Moens, W. (2004). Management of herbicide-tolerant oilseed rape in Europe: a case study on minimizing vertical gene flow. Environmental Biosafety Research, 3(3), 135-148. Retrieved from http://search.proquest.com/docview/896419029/fulltextPDF/13DDC94BB802EC3A6BF/1?accountid=12447

Genetically Modified Organism (GMO). (n.d.). Retrieved April 30, 2013, from GMO Compass website: http://www.gmo-compass.org/eng/glossary/115.genetically_modified_organism_gmo.html

Kameswara Rao, C. (2008, February 22). Gene Flow. Retrieved April 30, 2013, from http://www.plantbiotechnology.org.in/issue5.html

Kenner, R. (Director). (2008). Food, Inc. [Motion picture].

Lu, B.-R. (n.d.). Transgene Escape from GM Crops and Potential Biosafety Consequences: An Environmental Perspective. Retrieved from http://www.icgeb.org/~bsafesrv/pdffiles/Bao-Rong.pdf

McAfee, K. (2008). Beyond techno-science: Transgenic maize in the fight over Mexico’s future. Geoforum, 39, 148-160.

Münster, P., & Wieczorek, A. M. (2007). Potential gene flow from agricultural crops to native plant relatives in the Hawaiian Islands. Agriculture, Ecosystems & Environment, 119(1-2), 1-10. Retrieved from http://ac.els-cdn.com/S0167880906002593/1-s2.0S0167880906002593-main.pdf?_tid=6593fade-b5de-11e2-aa3b-00000aab0f6c&acdnat=1367797936_53b062f4b0d63cc328a892e34ffd56d6

Out-crossing and Gene Flow. (2006, December 12). Retrieved April 30, 2013, from GMO Compass website: http://www.gmo-compass.org/eng/safety/environmental_safety/170.genetically_modified_plants_out_crossing_gene_flow.html

Saez, C. (2011, March 30). US Farmers Sue Monsanto Over GMO Patents, Demand Right to Conventional Crops [Newsgroup post]. Retrieved from Intellectual Property Watch website: http://www.ip-watch.org/2011/03/30/us-farmers-sue-monsanto-over-gmo-patents-demand-right-to-conventional-crops/

Saved Seed and Farmer Lawsuits. (n.d.). Retrieved April 30, 2013, from Monsanto website: http://www.monsanto.com/newsviews/Pages/saved-seed-farmer-lawsuits.aspx

Which Crops Could Spread Their Genes? (2006, December 12). Retrieved April 30, 2013, from GMO Compass website: http://www.gmo-compass.org/eng/safety/environmental_safety/171.environmental_safety_which_crops_could_spread_genes.html


Annotated Sources:

Lu, B.-R. (n.d.). Transgene Escape from GM Crops and Potential Biosafety Consequences: An Environmental Perspective. Retrieved from http://www.icgeb.org/~bsafesrv/pdffiles/Bao-Rong.pdf

This report by Bao-Rong Lu came in very helpful for my research. Lu’s paper laid out much of the basic information that I required to provide a straightforward explanation of gene flow for the readers of the website. Lu’s clear format really helped me understand everything I was reading and contributed to my visuals as well. Lu’s credentials as well as his work with biodiversity and biosafety are evident in his writing and provided me with exactly the information that I needed.


McAfee, K. (2008). Beyond techno-science: Transgenic maize in the fight over Mexico’s future. Geoforum, 39, 148-160.

Kathleen McAfee’s article on maize in Mexico provided my paper with an important case study that highlighted both the cultural importance of crops in certain cultures and also the threat that faces organic farmers. Although I wasn’t able to take too much information from this article, it still gave good information and offered a great example for my paper.


Out-crossing and Gene Flow. (2006, December 12). Retrieved April 30, 2013, from GMO Compass website: http://www.gmo-compass.org/eng/safety/environmental_safety/170.genetically_modified_plants_out_crossing_gene_flow.html

This page of on the GMO Compass site was brief but provided me with further information about gene flow in GM crops. The page also listed some environmental concerns about the spread of transgenes that research on the subject aimed to address. We had used this site itself in class and I used other pages at other points of my paper, but I found that it contained useful facts for certain sections of my paper.


Saved Seed and Farmer Lawsuits. (n.d.). Retrieved April 30, 2013, from Monsanto website: http://www.monsanto.com/newsviews/Pages/saved-seed-farmer-lawsuits.aspx

Monsanto’s website also provided me with really interesting information. I really wanted to get their point of view incorporated into the parts of my paper regarding labeling because certain types of GM seeds legally are their intellectual property. Although I didn’t get to expand on this point further, the website provided a good counterargument.


Which Crops Could Spread Their Genes? (2006, December 12). Retrieved April 30,2013, from GMO Compass website: http://www.gmo-compass.org/eng/safety/environmental_safety/171.environmental_safety_which_crops_could_spread_genes.html

This source was another page on the GMO Compass site that listed a variety of crops as well as whether or not they posed a threat to biodiversity by spreading their genes. Many of the different plants didn’t have wild relatives to spread their genes to, which would make them relatively safe in terms of transgene flow. However, these plants were all studied in terms of their effects in Europe, so it provided only one perspective of the potential damage that could be done by each type of plant. While there was not enough room in my paper to analyze each crop, this page still provided useful information in terms of potential places where gene flow could occur.



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