Word cloud for the thesis (excluding citations and figure legends). I like how it looks like an ear of corn.

Abstract

Maize is a high yielding crop that provides a relatively high calorie source of food and feed, but focus on yield has not improved nutritional qualities. Some nutrients that are lacking in maize are iron and essential amino acids. In this dissertation some ways that genes from maize might be used to improve nutritional quality of maize are discussed, including improvement of bioavailable iron with maize globin and exploration of maize seed storage proteins. In addition, strategies to improve maize are explored, including breeding with mutations and transgenes and investigation of the effects of selection on transgenes.

Maize globin was found to be as bioavailable as ferrous sulfate, both when used as a forticant added to maize flour and when expressed in maize with an endosperm specific promoter. These results indicate that maize globin could be used to biofortify maize with highly bioavailable iron. Assessment of seed storage proteins in maize inbreds, landraces, and teosintes found unique proteins in teosintes that may be moved into maize through biotechnology or breeding to improve amino acid balance. Investigation of the effects of ensiling on seed storage proteins in maize used as ruminant feed found that longer ensiling times degraded some seed storage proteins, which may make the starch more digestible, but inoculation with Lactobacillus did not have an effect.

A variety of breeding methods can be used to improve qualities of maize. Maize transformed with a construct encoding green fluorescent protein controlled by a maize seed storage protein promoter was subjected to recurrent selection in order to increase transgene expression. This resulted in increased expression of the native gene with the same promoter, while unrelated traits were not changed. Backcrossing can be used to bring a mutation or transgene into a specific genetic background, while forward breeding can be used to improve characteristics of a line that carries a gene of interest.

Rationale

In many parts of the world, people are unable to obtain necessary nutrients from dietary sources. There are many factors that affect hunger and malnutrition, including political and social factors. Ideally, these factors will be changed to allow more people to lead healthy lives. Unfortunately, changing political and social systems can take decades, and in the meantime, many go hungry or malnourished. Maize is an important staple crop in parts of Africa, South America, and Central America. In addition, maize is an important feed crop in the developed and developing world. In this dissertation some ways that qualities of maize might be altered to help improve human quality of life are discussed, including improvement of bioavailable iron, amino acid balance, and investigation of effects of selection on transgenes.

Dissertation organization

This dissertation is divided into seven chapters. In the introductory chapter, an overall literature review is provided. The second chapter includes research conducted on maize hemoglobin. The goal of this research was to determine the potential of maize hemoglobin as an iron bioforticant. The third chapter includes research on transgene and native gene expression in response to selection for transgene expression. The goal of this research was to investigate the effects of selection on a transgene and to determine the relationship between expression of a transgene and a native gene with the same promoter. The fourth and fifth chapters are studies of seed storage proteins. The sixth chapter is about breeding with transgenes. In the seventh chapter, overall conclusions are discussed.

Note: Chapters four through six were previously published and were reprinted in my thesis with permission from the publishers. I doubt that permission extends to blog posts, so if you wish to see them and do not otherwise have access, please contact me directly. The citations for those chapters are as follows:

Flint-Garcia SA, Bodnar AL, Scott MP. Wide variability in kernel composition, seed characteristics, and zein profiles among diverse maize inbreds, landraces, and teosinte. Theoretical and Applied Genetics. 2009 Oct;119(6):1129-42. PMID: 19701625.

Hoffman PC, Esser NM, Shaver RD, Coblentz WK, Scott MP, Bodnar AL, Schmidt RJ, Charley RC. Influence of ensiling time and inoculation on alteration of the starch-protein matrix in high moisture corn. Journal of Dairy Science. 2010; 94(5):2465-2474.

Bodnar AL, Scott MP. Using mutations in corn breeding programs. The Handbook of Plant Mutation Screening. Ed. Meksem K, Kahl G. Wiley, 2010.

Field of Dreams in Dyersville, IA by John Bollwitt.

We often talk about the science of corn (aka maize) but there’s so much more to it. I’ll be leaving corn country soon to start a new job, and I know I’ll miss being in the center of so much maize.

Consider the natural beauty of a cornfield swaying in a summer breeze, with killdeer and red-winged blackbirds calling amongst the buzzing of grasshoppers.

It’s just a cornfield, but the combination of symmetry and asymmetry from afar and up close, of being in the presence of a plant that has been touched by humans for thousands of years, somehow makes it a very interesting place to be – even when I have many hours of pollinating or harvesting behind and ahead of me.

Each time I’ve visited the post office here in Ames, I’ve noticed a beautiful mural. This time, I asked about it and was directed to the Ames Historical Society website (the mural inspired this post). ”Evolution of Corn” was painted in 1938 by Lowell Houser. It is oil on canvas, an impressive 18’2” x 5’9”. The details are stunning, a tribute to corn farmers and breeders from both ancient and modern times. If you’re ever in Ames, I highly recommend seeing it in person.

In addition to all of the art you can find around the corner in Ames, Iowa State University has the largest art collection of any university in the United States. You can view it though the eyes of a student at the Art on Campus blog. It’s not all about corn, but agriculture is a strong theme. The art of Iowa State has inspired quite a bit of poetry, much of it with strong agriculture and science themes.

I’ve lived in many places, but Ames, Iowa has stolen my heart. Ames is such a lovely place, in part because of all the corn, and all of the art, but also because of the people. It’s so nice, we need our own song:

Ames, Ames, gee whiz,
Now we will sing and tell what it is,
A swell little city of which we are proud,
Her praises we’ll sing, in melody loud,
A beautiful city as ev’ry one knows,
In the heart of the state where the tall corn grows.

1) When talking about climate change, if we ever want to accomplish real communication, we need to find the scientists that are in the pragmatic* middle. These scientists in the pragmatic middle are more likely to be able to make themselves understood and are more likely to have things in common with the public in the pragmatic middle.

Does this apply to biotechnology? In some ways, I have to say no. Karl** and I are in the pragmatic middle in that, while we generally find the process of biotechnology to be safe and potentially useful, we agree that not all applications of biotechnology are beneficial and that many changes in regulation need to be made in order for biotechnology to fit into a diverse agricultural system. Neither of us are dogmatic about biotech, which you would think, as Matt says, would allow us to better communicate with the pragmatic middle. The problem that both of us face is: where is the public in the pragmatic middle, or how can we reach the public in the pragmatic middle?

The people who are talking about biotechnology in social media are decidedly not in the middle. Biotech is such a minor issue compared to things like the economy, unemployment, and even climate change, that those who are actively talking about biotechnology are firmly entrenched on either side of the badly drawn lines. People like Karl and I in the middle are drown out by the less pragmatic loud voices. I’m not sure what to do about that.

There is the added problem of people not believing the science. In both climate change and biotechnology, it seems that some individuals are insistent in their belief that scientists are somehow compromised, or bribed. In the case of climate change, there are accusations that even public scientists are motivated by greed, although this doesn’t make much sense as there are many other careers that are far far more lucrative than science that a person concerned with money might go into. In the case of biotechnology, there are accusations that all scientists are working for big industry, including public scientists, even when there is no evidence of a connection. Scientists need to learn how to translate their science into forms that the public can understand, but what is the point if people don’t believe scientists are a reliable source?

2) Studies, such as a survey of AAAS scientists, have shown that when it comes to climate change, politics has at least some effect on one’s stance on the science. While a high percentage of AAAS scientists accept anthropogenic climate change, a high percentage of those scientists are politically liberal. When you look at the small subset of AAS scientists that are politically conservative, that subset is much less likely to accept climate change. This indicates that acceptance of climate change science is not as greatly influenced by knowledge of the subject matter or ability to understand complex scientific topics.

Biotechnology does not seem to follow this pattern. Looking at scientists who accept the science of biotechnology, one finds politically liberal and conservative individuals. With climate change, an educational approach that aims to change minds through exposure to the science has not proven successful, possibly because of the strong political associations. With biotechnology, I hope that an educational approach could be more successful. As people understand more about the science of plant breeding and biotechnology, I hope that acceptance of the science, if not of the applications, of biotechnology could occur.

Real changes in policies, regulation, agriculture in general, won’t be possible unless at least some of the public is willing to look at the science and at least some of the scientists and regulators are able to realistically understand the concerns of the public. How can we communicate when perceived bias and political leanings get in the way of one or both sides? How can the pragmatic middles find each other and work towards better policy?

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*pragmatic |pragˈmatik| adjective  - dealing with things sensibly and realistically in a way that is based on practical rather than theoretical considerations : a pragmatic approach to politics.

** I have taken the liberty of bringing Karl, my co-executive editor in this blogging project, into my discussion here because in our discussions I feel that we have similar opinions on the subject of biotechnology and many other things. If this assumption is in error, it is entirely my fault and not his.

The Center for Food Safety has a “new” document to bring to the discussion: an opinion (pdf) written by the National Marine Fisheries Service regarding a U.S. Army Corps of Engineers proposal about ocean net pens to raise finfish off the coast of Maine that was written in 2003. CFS talks about this letter in a blog post titled Newly Disclosed Government Documents Conclude GE Salmon Pose A Critical Threat To Marine Environments. Let’s just say there’s a few errors in the reasoning found in the blog post and indeed all over the GFS site about genetically engineered fish. Here, I’ll go over the blog post (I’ll let our excellent commenters take a look at the rest of the site) and discuss some of the errors.

The post opens with:

Adding a new twist to the controversy over genetically engineered (GE) salmon, the Center for Food Safety (CFS) revealed today that, in recent hearings on transgenic fish, the U.S. Food and Drug Administration (FDA) knowingly withheld a Federal Biological Opinion by the U.S. Fish and Wildlife Service (FWS) and National Oceanic and Atmospheric Administration (NOAA) prohibiting the use of transgenic salmon in open-water net pens pursuant to the U.S. Endangered Species Act (ESA).

Is this fish crying? Maybe she read the CFS blog post.

The problem is that the opinion wasn’t about genetically engineered salmon. It was about the risks of any ocean farmed salmon, with a fairly small amount of discussion of transgenic fish (less than 3 pages of a document totally 101 pages, with a full 61 pages of text). Is this opinion relevant to the application by Aqua Bounty to raise transgenic salmon in two very specific land based facilities? Perhaps. Here’s everything the report says about transgenic fish:

page 27 Transgenic salmonids are prohibited at these facilities [referring to a list of permitted ocean pen fish farms]. Transgenic salmonids are defined as species of the genera Salmo, Oncorhynchus and Salvelinus of the family Salmonidae and bearing, within their DNA, copies of novel genetic constructs introduced through, recombinant DNA technology using genetic material derived from a species different from the recipient, and including descendants of individuals so transfected. This prohibition does not apply to vaccines.

page 34-35 [at the very end of the section Disease Factors, Predators, and Competitors discussing concerns of farmed salmon] Atlantic salmon and rainbow trout produced by the aquaculture industry (including non-North American strains and potentially transgenics) that escape from hatcheries or net pens also compete with wild Atlantic salmon.

page 74-75 [under the heading Transgenics]

The potential use of transgenic salmonids in the aquaculture industry has recently been identified as a possible threat to wild Atlantic salmon populations. Transgenic salmonids include fish species of the genera Salmo, Oncorhynchus, or Salvelinus in the family Salmonidae that bear, within their DNA, copies of novel genetic constructs introduced through recombinant DNA technology using genetic material derived from a species different from the recipient, and descendants of any individuals so transfected. Escaped, reproductively viable transgenic salmon could interbreed with wild fish. Research to develop transgenic fish for aquaculture increased through the 1980s and had advanced to the extent that, by 1989, production of 14 species of transgenic fish, including Atlantic salmon, had been reported (Kapuscinski and Hallerman 1990).

Transgenic fish produced for culture in marine net pens must be selected to survive under nearly natural physical and chemical environmental conditions. If they escape, therefore, it is likely that. a portion of them will survive. In a study by Sheela et al. (1999), transgenes were inherited in many progeny from transformed fish, as determined through DNA analyses and through expression of the reporter gene. If an introduced construct can find its way onto or into a chromosome before the first cell division of a newly-fertilized egg, all the cells in the developing organism, including future germ cells, will contain copies (Lutz 2000). The transmission of novel genes to wild fish could lead to physiological and behavioral changes, and traits other than those targeted by the insert gene are likely to be affected. Ecological effects are expected to be greatest where transgenic fish exhibit substantial altered performance. Such fish could destabilize or change aquatic ecosystems (Kapuscinski and Hallerman 1990).

In a study by Cook et al. (2000), growth-enhanced transgenic Atlantic salmon exhibited a 2.62- to 2.85-fold greater rate of growth relative to non-transgenic salmon, over the body weight interval examined. This study found that the transgenic experimental subjects possessed the physiological plasticity necessary to accommodate acceleration in growth well beyond the normal range for this species, with few effects other than a greater appetite and a leaner body (Cook et al. 2000). Because aquatic ecosystems function through complex interactions involving transfers of energy, organisms, nutrients, and information, it is difficult to predict the community-level impacts of releasing transgenic fishes that exhibit one or more types of phenotypic change (Kapuscinski and Hallerman 1990). At this time, more research is needed to identify the impacts that escaped transgenic salmon would have on natural populations and their habitat before use for commercial aquaculture is considered.

Research and development efforts on transgenic forms of Atlantic salmon and rainbow trout are currently being directed toward their potential for sea pen aquaculture. Emphasis has been placed on enhancement of growth and low water temperature tolerance through the transfer of genetic material from other cold-tolerant species, such as flounder. In 2002, the Food and Drug Administration received an application for approval to sell and possibly grow transgenic salmon in the United States for use by the aquaculture industry.

The prohibition on the Use of transgenic salmonids at existing marine sites off the coast of Maine (Special Condition No. 2) will eliminate the potentially adverse disease and ecological risks posed by the use of transgenic salmonids in aquaculture. The risk posed by a transgenic salmonid to wild salmon would be greatly affected by the specific gene manipulation conducted. Anyone proposing the use of transgenic salmonids in aquaculture would need to provide information on the methods used and the potential for genetic, fish health and ecological impacts on wild stocks. This information would have to be evaluated to determine the level of risk posed to wild Atlantic salmon stocks and a decision would have to be made as to whether that level of risk was acceptable or not. The use of transgenic salmonids will be prohibited under Condition No. 2 until such time as these risks can be evaluated.

A slightly better than superficial reading of this discussion of transgenic salmon reveals that the National Marine Fisheries Service is strongly recommending a ban on transgenic salmon in ocean pens due to concerns that the transgene will make the fish more fit than non-transgenic fish and that such a transgene would spread through natural populations if the accidentally released transgenic fish were reproductively viable. Anyone wanting to use transgenic salmon in aquaculture would need to provide clear information about the specific risks they may pose to wild salmon (which is exactly what Aqua Bounty did). I’m not sure if this recommendation was codified – if anyone knows, please provide that information in the comments.

CFS concludes something a little different:

“This adds further evidence that in fact GE salmon pose a serious threat to marine environments and is another compelling reason for the FDA not to approve the fish for commercial use,” said Andrew Kimbrell, Executive Director of the Center for Food Safety.  “While the FDA applauded the company’s choice of land-based containment as responsible, it never revealed that it is illegal in the U.S. to grow genetically engineered salmon in open-water net pens.”

Is it actually illegal to raise transgenic salmon in open water pens? If it is illegal, is that relevant to a discussion of land based aquaculture? The differences between risks of ocean based compared to land based aquaculture are quite large, whether we’re discussing transgenic or non-transgenic fish. All ocean based aquaculture was determined by the same report to be quite risky to wild fish:

page 79 [Conclusion] Based on the close proximity of hundreds of fish pens to the GOM DPS [Gulf of Maine Distinct Population Segment] of Atlantic salmon, and the anticipated continued escapes, the best available scientific data and commercial information indicates that the continued operation of Maine aquaculture facilities poses a threat to individual wild salmon because escaped aquaculture salmon compete for food and habitat, disrupt redds, interbreed, thus disrupting breeding, feeding and sheltering of wild Atlantic salmon. Aquaculture facilities may also promote the transfer of disease and parasites to wild salmon, which may also adversely affect wild salmon.

The National Marine Fisheries Service thinks that the permit procedure and the special conditions the U.S. Army Corps of Engineers recommends will help mitigate the risk to wild fish. The special conditions (presumably applying to ocean pen aquaculture since that’s what the entire opinion is about) are:

(1) eliminating the use of non-North American strain Atlantic salmon; (2) developing containment management systems with loss control plans and audits; (3) marking aquaculture fish; (4) prohibiting the use of transgenic salmonids; and (5) requiring fish health certification before stocking alternative salmonids.

CFS thinks that this report means that transgenic fish are a great threat, but it’s clear that National Marine Fisheries Service thinks that all ocean pen aquaculture is a great threat. National Marine Fisheries Service seems to think that these conditions are enough to mitigate the risk, although I am skeptical. Anyway, the only thing that sets transgenic fish apart is that there are more unknowns, or at least there were at the time, when the literature indicated that fast-growing salmon would be better able to compete than salmon without a growth hormone transgene. Later studies have shown that the fast growing salmon have behavioral phenotypes that actually make them less likely to survive than non-transgenic salmon. For example, fast growing salmon are more fearless such that they are more likely to be eaten by predators.

An opinion (pdf) by the Environmental Protection Agency in 2001 on the same subject (whether there should be ocean pen fish farms allowed off the coast of Maine where there are a lot of wild salmon) says pretty much the same thing, with some of the text seemingly cut and pasted from the 2001 Environmental Protection Agency opinion to the 2003 National Marine Fisheries Service opinion.

Anyway, CFS thinks that since these two documents weren’t presented earlier, that must mean the FDA is keeping information from the public. Maybe, but it seems more like these documents weren’t relevant to the discussion of Aqua Bounty’s application for land based facilities rearing fish that are sterile 98% of the time or more (on average).

The CFS post concludes:

Conversations between NOAA and FWS staff in 2009 highlight a Swedish study that found that in simulated escapes, transgenic fish have a “considerably greater effect on the natural environment than hatchery-reared, non-transgenic fish when they escape.” The study further noted that genetically modified fish survive better when there is a shortage of food, benefit more than non-transgenic fish from increasing water temperatures, and can be more resistant to environmental toxins that may ultimately end up in consumers.

Why does’t anyone ever provide a proper citation? According to Web of Science, there were 2,044 papers about salmon published in 2009. Out of the subset of 28 papers that also included the word transgenic, I think the study they’re referring to is:

L. Fredrik Sundström, Wendy E. Tymchuk, Mare Löhmus, & Robert H. Devlin (2009). Sustained predation effects of hatchery-reared transgenic coho salmon Oncorhynchus kisutch in semi-natural environments. Journal of Applied Ecology, 46, 762-769 : 10.1111/j.1365-2664.2009.01668.x

This study didn’t mention toxins at all, or temperatures, but did find that transgenic fish with a growth enhancing gene ate more than non-transgenic fish, at least at first. After about two months, all fish were the same size (not significantly different sizes), including: non-transgenic fish, transgenic fish that were fed an amount of food that restricted them to approximately the same size as non-transgenic, and transgenic fish that were allowed to eat as much as they wanted. The reduced swimming capacity of the transgenic fish that were allowed to eat as much as they wanted led to higher ability of prey to swim away, leaving those prey for other fish. It wasn’t apparent from this study that transgenic fish would have a greater effect on the environment than non-transgenic farmed fish.

Finally, there wasn’t any mention in the Environmental Protection Agency or National Marine Fisheries Service documents about  risks of fish bred for specific traits such as fast growth to wild fish. The natural variation in salmon populations for size, growth rate, etc is pretty wide. It’s very possible that a breeding program could develop super salmon without any genetic engineering and those super salmon could potentially be a threat to wild salmon, particularly if they were farmed as reproductively viable individuals in ocean pens near by wild salmon populations. Perhaps this is covered by special condition 1: “eliminating the use of non-North American strain Atlantic salmon”? This is unlikely to have any real positive effect, since the problem of ocean farmed salmon escaping is that they spread a) disease and b) genes that are far less diverse than those in wild populations even when they are of the same strain. I stand by my previous assertion that both ocean farmed non-transgenic salmon and fishing of wild fish are a greater risk to wild salmon than transgenic salmon in land based facilities.

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Hat tip to Mark Bittman (@bittman) for creatively tweeting about the CFS blog post:

FDA hid evidence about threats posed by genetically engineered salmon. Your tax $ at work: http://bit.ly/aYJGbl

I’ve been a strong advocate of Bittman’s work. He advocates a diet that is mostly plant based  for environmental and health reasons but allows meat as an indulgence. I have a lot of respect for his stepping out with this rare practical viewpoint. I love his How to Cook Everything Vegetarian and recommend it to everyone, especially if you’re not an experienced cook. But, I don’t love uncritical tweets. Mark, if you happen to read this, please, please consider some critical thinking material such as the Skeptoid podcast where Brian Dunning takes the listener through the process of claim, evidence, evaluation of claim.

Miso glazed Atlantic salmon by ulterior epicure via Flickr.

Aqua Bounty Technologies, Inc. has recently applied for deregulation of AquAdvantage salmon — salmon that have been genetically engineered to grow faster than wild-type salmon. These salmon have the potential benefit of providing high-quality animal protein without putting additional pressure on declining wild fish stocks.

However, these salmon present some potential risks that warrant examination. First, effects on the health and welfare of the animals must be determined. Second, if genetically engineered salmon were to escape and become established in the wild, native salmon populations or other aspects of the ecosystem could be adversely affected. Third, this genetically engineered trait or some part of the development or rearing process might have health consequences for consumers. These risks must be fully addressed before deregulation can be considered.

The science behind the salmon

In 1989, the founder animal of the AquAdvantage salmon line was created by injecting an Atlantic salmon (Salmo salar) egg with a gene construct (termed opAFP-GHc2; figure 1a) that contained a promoter and termination region from the ocean pout (Zoarces americanus) antifreeze gene and a growth hormone gene from Chinook salmon (Oncorhynchus tshawytscha). The ocean pout antifreeze promoter was previously shown to be constitutive, or continually expressing, in salmon (1), in contrast to the native growth hormone promoter in salmon, which only expresses in response to certain environmental cues such as day length and temperature (2).

The Chinook and Atlantic salmon growth hormone genes are very similar. A BLAST comparison of the mRNA for each (GenBank S50867.1 and X14305.1, respectively) found 90% (1013/1126) of the nucleotides were identical and only 6% gaps (70/1126). A comparison of the protein sequences found 95% (198/210) of the amino acids were identical, 98% (205/210) of the amino acids were similar, and 0% gaps.

A single copy of the construct was integrated into the Atlantic salmon genome. The genomic sequence flanking the insert on both sides consisted of a 35 base pair repeat, and there was no evidence of mutational effects due to insertion (3). During transgene integration, a rearrangement of the construct took place (termed EO-1ɑ; figure 1b), which resulted in the integration of a small fragment of the plasmid into the salmon genome. This fragment did not contain any coding sequences. The promoter was rearranged such that part of the promoter was integrated downstream of the termination region. There is evidence that the truncated promoter has reduced expression compared to the full promoter in salmon (4), but the truncated promoter remains functional. The founder animal was backcrossed to wild-type Atlantic salmon, and the EO-1ɑ gene sequence was identical in the second and fourth generations, indicating that the insertion is stable (3).

Figure 1a. Gene construct, termed opAFP-GHc2, used to develop AquAdvantage salmon as integrated in the pUC18 plasmid. Figure 1b. Gene construct as integrated into the salmon genome, termed EO-1ɑ (3). Not to scale.

Animal growth, health, and welfare

Figure 2. Wild type Coho salmon and salmon over expressing growth hormone that have been exposed to different environments (6).

Salmon have wide variability of phenotypes that allow them to adapt to a variety of environmental conditions. This phenotypic plasticity means that even genetically similar fish may have very different phenotypes when exposed to different environments. For example, Coho salmon (Oncorhynchus kisutch) overexpressing growth hormone from sockeye salmon (Oncorhynchus nerka) (5) showed different phenotypes depending on environment. Transgenic fish fed to satiation in hatchery conditions grew almost three times longer than controls while transgenic fish in a simulated natural environment grew to be only 20% longer than controls (6), as shown in figure 2. AquAdvantage salmon are significantly larger than wild-type siblings under hatchery conditions (p<0.0001) (7), as shown in figure 3. It is not expected that AquAdvantage salmon would attain such large sizes in a non-hatchery environment.

Figure 3. Mean body size with standard deviation, maximum, and minimum body size in grams of four groups of salmon: diploid and triploid AquAdvantage salmon expressing transgenic growth hormone and diploid and triploid wild type salmon. N = 309, 369, 306, and 464 respectively (7).

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Many studies have found that overexpression of growth hormone can result in changes in a variety of traits, including behavior, swimming ability, and body structure in salmon. Body malformations found in salmon and carp overexpressing growth hormone can mean the fish might not be able to swim as fast as wild type fish (8). However, these problems may not be due to the presence of the transgene. For example, vertebral malformation in wild type salmon may result from a variety of causes, including fast growth rate (9). Malformations may also be due to the triploid induction process as described below.

The first generations of AquAdvantage salmon had body malformations at a higher incidence than in wild type controls, but later generations had rates similar to control salmon (7). Aqua Bounty Technologies, Inc. has submitted to the FDA’s Center for Veterinary Medicine (7) ten years of data indicating no difference in animal health and welfare between AquAdvantage and wild type salmon, but that information is not publically available.

Preventing escape

On 25 August 2010, Aqua Bounty Technologies, Inc. submitted an environmental assessment (7) for AquAdvantage salmon to the FDA’s Center for Veterinary Medicine as part of their request for deregulation. The request is isolated to one specific egg production facility and one specific fish production facility, not for an unconditional deregulation. Aqua Bounty plans to use many redundant systems, including biological, physical, and environmental, at these facilities to prevent release of genetically engineered salmon into the environment.

Biological containment

One of the most effective measures that will be used to prevent AquAdvantage salmon from breeding with wild salmon is the use of triploid fish. Most wild type fish are diploids, having two copies of each chromosome, while triploids have three copies. Triploid fish do not produce gametes, so are sterile. Triploidy can be induced by treating fertilized fish eggs with pressure, temperature, or chemicals. The treatment itself can have a negative effect, as shown by experiments comparing triploid and diploid fish that had the same treatment to non-treated diploids and triplods that had been produced with other methods (10). Exact treatment parameters can be adjusted to reduce negative effects and increase the incidence of triploid induction for each fish species and variety.

Pressure treatment will be used to produce triploid AquAdvantage salmon. This treatment was successful at creating 98.9% or more triploids, with 1.1% or fewer eggs remaining diploid (11). Testing of each batch of eggs will be conducted, and any batch that contains 5% or more diploids will be destroyed (7,11). Any diploid individuals are capable of reproduction, so the possibility of their escape must be controlled with other measures.

Figure 4. 2006 record grass carp weighing 59 pounds, 12 ounces caught by Mark Kronyak of Middletown, New Jersey (12).

Triploid fish of many species have been used for at least ten years in countries around the world in commercial fisheries and recreational fishing areas to prevent farmed or stocked fish from breeding with wild fish. Trout, carp, and salmon are commonly stocked as triploids and can reach very large sizes, as in Figure 4 (12). Larger body size and higher quality meat result because the animals do not undergo the stress of reproduction (10,13).

Triploids cells are larger than diploids because of the increase in the amount of DNA in the nuclei. This results in an increased cell size, although overall body size is not larger compared to pre-reproduction age diploids. Having a larger cell size means the cell surface area available for gas exchange is decreased relative to the volume of the cell, compared to wild type cells, resulting in increased oxygen demand of triploid fish compared to diploids (10).

Triploid and diploid fish in most species are indistinguishable from one another until after maturity, when diploids will divert energy to reproduction and triploids use that energy to grow in size. Triploid Chinook salmon are phenotypically indistinguishable from and have very similar gene expression as diploids except when under extreme stress conditions. Reduced immune function of triploids may be due to the pressure treatment or due to abnormal gene interactions arising from the third complement of genes (14). Triploid salmon overexpressing growth hormone have reduced size and growth rate relative to diploid salmon overexpressing growth hormone, but the growth rate of both is higher than that of wild type controls (5,7).

Triploid females have a complete loss of reproduction ability, but some triploid males retain the ability to produce sperm. To avoid the possibility of any male eggs being produced, all fish used to produce sperm for AquAdvantage salmon egg production are neomales. There is great flexibility of gender in many fish species, such that genetically male fish may develop into females and vice versa when in the presence of certain hormones. In the case of AquAdvantage salmon, genetic females that are homozygous for the EO-1ɑ gene are induced into producing male gonads with 17-methyltestosterone, a fairly common procedure in modern aquaculture and in fish reproduction research. Sperm produced by these fish are used to fertilize wild type Atlantic salmon eggs, resulting in all female fish that each have one copy of the EO-1ɑ gene (7,11). The possibility that a male fish will be produced with this method is zero, because no male sex chromosomes are involved.

Physical containment

Because a small percentage (1.1% or less) of AquAdvantage salmon could be diploids that are capable of reproduction, additional containment methods are necessary. Physical containment at the egg and fish production facilities will provide multiple layers of security. These include on-facility living quarters for security personnel, security cameras, and 8’ chain link fencing around each property, among other measures. Numerous filters, nets, and other containment devices reduce likelihood of escape to less than 1%. At the egg production facility, chlorine is used in the drainage area to kill eggs that escape filters (7). Because all farmed salmon have reduced ability to survive in the wild, and 98% or more of AquAdvantage salmon are sterile, the likelihood of escaped animals interfering with the natural ecosystem, becoming established in the environment, or breeding with sexually compatible fish nearby is extremely small. Animals that do escape the redundant means of containment will be met with environmental conditions that make survival unlikely.

Environmental containment

The land based, fresh water egg production facility is located in Prince Edwards Island, Canada. Historically, Atlantic salmon inhabited the fresh bodies of water in this area, but no wild salmon populations remain in the area due to overexploitation, barriers to migration, and acid rain. In the winter, temperatures in bodies of water near the facility are too low for salmon, although spring and summer temperatures are hospitable to salmon (7). The barriers to migration would prevent escaped animals from moving out to sea during the summer. In addition, relatively high salinity in the nearby river would further reduce likelihood of survival for animals acclimatized to fresh water.

The land-based fish production facility is located at a high altitude in Panama near a river that drains to the Pacific ocean. Much of the river water (up to 100% in the 4 – 5 month dry season) is used for power generation, and the canals that control water flow to power generation facilities are not suitable for salmon. In addition, the dams provide a physical barrier to movement downstream. If animals were able to navigate the barriers, the river closest to the facility does have conditions that are favorable to salmon, but in the lower parts of the river, water temperatures are lethal to salmon (7). While the areas near the facility could sustain young salmon for a short time, escape to the Pacific ocean is very unlikely.

Human health

General concerns with AquAdvantage salmon, or any other genetically engineered organism intended for human consumption, include increased allergenicity and unintended changes in the composition of edible tissues. Wild type salmon is a known allergen, so AquAdvantage salmon is expected to cause allergic reactions in individuals that are allergic to salmon. The amino acid sequence of Chinook growth hormone is unlike the sequence of known protein allergens (11). Nonetheless, additional analysis of allergenicity would be useful. Allergenicity studies conducted by Aqua Bounty Technologies Inc. were determined to be unsatisfactory by the Food and Drug Administration’s Center for Veterinary Medicine, due to small sample size and inappropriate statistical analysis. A reanalysis of the data by FDA CVM found that the allergenic potency of triploid salmon expressing EO-1ɑ was not significantly different from the control, although additional testing is needed to determine the allergenicity of diploid salmon expressing EO-1ɑ (11). Diploid amago salmon (Oncorhynchus rhodurus, also known as Oncorhynchus masou ishikawae) expressing growth hormone did not have increased allergenicity compared to control salmon (15).

The carbohydrate, ash, moisture, protein, total fat, vitamin, mineral, amino acid, and fatty acid composition of the edible tissue of AquAdvantage salmon was compared to control salmon by Aqua Bounty Technologies, Inc. The only tested compound that exceeded the range of values found in the controls was vitamin B6 (0.77 and 0.72 mg per g tissue in AquAdvantage and control, respectively), but the amount of vitamin B6 is less than that found in tuna (0.81 mg/g), another commonly consumed finfish (11). Consumption of normal amounts of AquAdvantage salmon is unlikely to result in daily intake of vitamin B6 that exceeds the recommended maximum amount of 100 mg/day. Omega 3 and omega 6 fatty acids are found at similar amounts in AquAdvantage and control salmon (11).

Specific concerns with AquAdvantage salmon include increased hormone content in edible tissues. The growth hormone content in AquAdvantage salmon and non-genetically engineered control salmon were both below the lower limit of quantitation (10.40 ng/g of tissue), while amounts of estradiol, testosterone, 17- ketotestosterone, T3, and T4 were not significantly different in the two groups. The only statistically different concentration was for insulin-like growth factor 1 (IGF-1), with a mean of 7.34 ng/g in the control group and 10.26 ng/g in the test group (11).

The overall amount of IGF-1 present in AquAdvantage or wild type salmon is similar to or lower than the amount found in other animal products. For example, milk from cows treated with growth hormones, milk from cows not treated with growth hormones, and organic milk were found to have 3.12, 2.04, and 2.73 ng IGF-1 per mL of milk, respectively (16). Beef cattle were found to have greater than 275 ng IGF-1 per mL of blood (17) without application of growth hormone. For comparison, adult human males that consume 60.1 g of protein daily have 168 ng of IGF-1 per mL of blood and adult human males that consume 81.7 g of protein daily have 200 ng of IGF-1 per mL of blood (18). Consumption of normal amounts of AquAdvantage salmon would result in dietary amounts of IGF-1 that are no greater than a normal diet containing other animal foods.

The sequence and structure of IGF-1 varies by species such that fish IGF-1 is unlikely to react at a biologically significant level with mammalian IGF-1 receptors. The IGF-1 protein sequences for human (NM_001111283.1) and Atlantic salmon (EF432852.2) are quite dissimilar. A BLAST comparison of the protein sequences found 64% (90/141) of amino acids were identical and 76% (106/141) were similar. Contrast this with a BLAST comparison of human and bovine (NM_001077828.1) IGF-1 protein sequences, which are 96% (129/135) identical and 96% (129/135) similar.

Comparison of binding activity of IGF-1 proteins from a variety of species to human IGF-1 receptors found that salmon IGF-1 was 2 to 3 times less effective at binding than mammalian or marsupial IGF-1; however, salmon IGF-1 was better able to bind to sheep IGF-2 receptors than human IGF-2 (19). Further testing is needed to determine the interspecies interactions of IGF-1 and IGF-2 proteins and receptors. It is worth noting that, while consumption of bovine IGF-1 does cause elevated IGF-1 levels in humans, the dietary IGF-1 is degraded, indicating that bovine IGF-1 does not directly contribute to increased human IGF-1 levels (20). Fish IGF-1 can be expected to have similar degradation. Human IGF-1 levels increase with increased dietary protein, whether that protein is from animal or vegetable sources (18).

Conclusions

The FDA considers the EO-1ɑ gene sequence in AquAdvantage salmon as an animal drug rather than considering the salmon as a novel food (21). This approach has advantages and disadvantages, but all available evidence suggests that AquAdvantage salmon are within the normal range of wild type triploid fish for all characteristics except growth rate, with few exceptions. Similar increases in body weight can be achieved with injection, oral application, or controlled release of a variety of compounds, including growth hormone and IGF- 1 (5). A major disadvantage to considering the EO-1ɑ gene sequence as an animal drug is that it has led to consumer distrust and confusion. Even triploidization itself has led to some consumer concern (10), indicating that efforts to educate consumers on the risks and benefits of technologies used in animal agriculture may be helpful. Another disadvantage of considering the EO-1ɑ gene sequence as an animal drug is that it allows AquAdvantage to keep some experimental results confidential to protect their intellectual property. Even though the FDA has access to those results, the withholding of data from the public has only served to increase distrust of AquAdvantage salmon and of the FDA itself.

Widely circulated fears about risks of AquAdvantage salmon do not seem to be based on the available research. Based on the research, animal health and welfare is not different from that of other triploid, hatchery reared fish. Animal welfare issues as well as sustainability issues related to fish farming are important and should be considered, but these issues affect all fish farming and are not unique to AquAdvantage salmon. Human health risks are no greater than that posed by other meats and animal products. Additional tests could be conducted, such as larger scale allergenicity testing of AquAdvantage salmon, but the available research does not indicate that such tests are likely to find significant differences from wild type salmon. Further research of the potential effects of dietary IGF-1 from different species on human health would be useful, but this question is not unique to AquAdvantage salmon. Long or short term feeding studies of AquAdvantage salmon to test animals are not scientifically necessary because of the lack of evidence that the edible tissue is different from that of wild type salmon, but feeding studies comparing AquAdvantage salmon to commonly eaten salmon species may be needed to assuage consumer concerns.

The available research and the containment measures proposed by Aqua Bounty indicate that the environmental risks of AquAdvantage salmon are minimal. However, despite all containment efforts, less than 1% of AquAdvantage salmon could escape from the rearing facility and, on average, 1.1% of the salmon will be diploids. The possibility that one diploid AquAdvantage salmon would escape from the facility and survive climactic, physical, and ecological barriers is extremely unlikely, amounting to less than 0.01% of all fish reared or 1 fish in 10,000. Reproductive age for Atlantic salmon depends on latitude such that reproductive age is 50 weeks at the latitude of Prince Edwards Island (22). An escaped fertilized egg may meet a favorable environment for survival, but is unlikely to survive to 50 weeks. Breeding age of Atlantic salmon at the latitude of the hatchery facility in Panama is not known because Atlantic salmon are not known to survive at low latitudes where water temperature is so high. Still, if escape were to happen and the escapee reached reproductive age, what would the result be?

The salmon reproductive process requires complex mating and nesting behavior as well as fresh running water with a gravel bed. A sexually compatible male must be present at the time of spawning (22). In the waters near the egg and fish rearing facilities, neither sexually compatible males nor gravel beds are available (7). However, even though attempts to reintroduce salmon and other species to the rivers near the egg facility and rainbow trout in the rivers near the fish rearing facility have failed in the past (7), future attempts may be successful and river bed conditions may change. Hybridization between some trout and salmon species is possible, but generally produce sterile offspring (23). Research is needed to determine the survivability and fertility of Atlantic salmon and rainbow trout hybrids. The energy investment in reproduction is so high for female Atlantic salmon that there is a 60% or higher probability of death post-spawning (22).

All AquAvantage salmon carry only one copy of the EO-1ɑ gene sequence, so if an escaped diploid AquAvantage salmon reached reproductive age and found a suitable mate, only one half of her offspring would carry the gene sequence. Those that carried the EO-1ɑ gene sequence would, according to available research, be at a disadvantage to their siblings that did not. Salmon over expressing growth hormone under wild conditions have decreased swimming speed which results in higher death rates due to the decreased ability to swim away from predators and decreased ability to catch prey (8). Any advantage that EO-1ɑ carrying progeny might have over wild type fish in size and growth rate will likely be cancelled out by negative effects and the gene will either be eliminated from the wild population by natural selection or remain at a very low gene frequency. Studies in near natural environments on the survival rates of fish over expressing growth hormone compared to wild type fish as well as on dynamics of mixed populations are needed.

The final question about AquAdvantage salmon is how additional salmon on the market will affect the wild salmon fishing industry, the farmed salmon industry, and the tax revenues to the states that support those industries. These industries and their representatives have expressed concern that AquAdvantage salmon will lead to decline of wild caught salmon due to escape of farmed salmon and increased competition in the marketplace. Neither of these issues are specific to AquAdvantage salmon, but are concerns related to all fish farming. For example, domesticated fish have less genetic diversity than wild fish so there is concern that accidental releases of large numbers of domesticated fish could cause decreased ability to adapt in wild populations (24). Because of fewer controls against escape, fish farming as it exists today could be considered more risky for wild populations than AquAdvantage salmon will be. As for increased competition, voluntary labeling such as “wild caught” and “not genetically engineered” will allow for different products to prove themselves in the marketplace.

1. Devlin, R., Yesaki, T., Donaldson, E., Du, S., & Hew, C. (1995). Production of germline transgenic Pacific salmonids with dramatically increased growth performance Canadian Journal of Fisheries and Aquatic Sciences, 52 (7), 1376-1384 DOI: 10.1139/f95-133
2. Björnsson BT (1997). The biology of salmon growth hormone: from daylight to dominance. Fish Physiology and Biochemistry 17:9-24 .
3. Yaskowiak ES, Shears MA, Agarwal-Mawal A, & Fletcher GL (2006). Characterization and multi-generational stability of the growth hormone transgene (EO-1alpha) responsible for enhanced growth rates in Atlantic Salmon. Transgenic research, 15 (4), 465-80 PMID: 16906447
4. Butler TM, & Fletcher GL (2009). Promoter analysis of a growth hormone transgene in Atlantic salmon. Theriogenology, 72 (1), 62-71 PMID: 19324402
5. Devlin, R. (2004). Growth, viability and genetic characteristics of GH transgenic coho salmon strains Aquaculture, 236 (1-4), 607-632 DOI: 10.1016/j.aquaculture.2004.02.026
6. Sundström LF, Lõhmus M, Tymchuk WE, & Devlin RH (2007). Gene-environment interactions influence ecological consequences of transgenic animals. Proceedings of the National Academy of Sciences of the United States of America, 104 (10), 3889-94 PMID: 17360448
7. Aqua Bounty Technologies, Inc (2010). Environmental assessment for AquAdvantage salmon.
8. Hu W, & Zhu Z (2010). Integration mechanisms of transgenes and population fitness of GH transgenic fish. Science China. Life sciences, 53 (4), 401-8 PMID: 20596905
9. Witten P, Gil-Martens L, Huysseune A, Takle H, & Hjelde K (2009). Towards a classification and an understanding of developmental relationships of vertebral body malformations in Atlantic salmon (Salmo salar L.) Aquaculture, 295 (1-2), 6-14 DOI: 10.1016/j.aquaculture.2009.06.037
10. Piferrer F, Beaumont A, Falguière J, Flajšhans M, Haffray P, & Colombo L (2009). Polyploid fish and shellfish: Production, biology and applications to aquaculture for performance improvement and genetic containment Aquaculture, 293 (3-4), 125-156 DOI: 10.1016/j.aquaculture.2009.04.036
11. Food and Drug Administration Center for Veterinary Medicine Veterinary Medicine Advisory Committee (2010). Briefing Packet for the Food and Drug Administration Center for Veterinary Medicine Veterinary Medicine Advisory Committee.
12. New Jersey Division of Fish and Wildlife (2006). State record grass carp caught.
13. Matthews J. Why Santa Ana River Lakes and Corona have the biggest rainbow trout. Outdoor News Service.
14. Ching B, Jamieson S, Heath JW, Heath DD, & Hubberstey A (2010). Transcriptional differences between triploid and diploid Chinook salmon (Oncorhynchus tshawytscha) during live Vibrio anguillarum challenge. Heredity, 104 (2), 224-34 PMID: 19707232
15. Nakamura R, Satoh R, Nakajima Y, Kawasaki N, Yamaguchi T, Sawada J, Nagoya H, & Teshima R (2009). Comparative study of GH-transgenic and non-transgenic amago salmon (Oncorhynchus masou ishikawae) allergenicity and proteomic analysis of amago salmon allergens. Regulatory toxicology and pharmacology : RTP, 55 (3), 300-8 PMID: 19679156
16. Vicini J, Etherton T, Kris-Etherton P, Ballam J, Denham S, Staub R, Goldstein D, Cady R, McGrath M, & Lucy M (2008). Survey of retail milk composition as affected by label claims regarding farm-management practices. Journal of the American Dietetic Association, 108 (7), 1198-203 PMID: 18589029
17. Juniper, D., Browne, E., Bryant, M., & Beever, D. (2007). Digestion, rumen fermentation and circulating concentrations of insulin, growth hormone and IGF-1 in steers given maize silages harvested at three stages of maturity Animal Science, 82 (01) DOI: 10.1079/ASC200513
18. Giovannucci E, Pollak M, Liu Y, Platz EA, Majeed N, Rimm EB, & Willett WC (2003). Nutritional predictors of insulin-like growth factor I and their relationships to cancer in men. Cancer epidemiology, 12 (2), 84-9 PMID: 12582016
19. Upton Z, Yandell CA, Degger BG, Chan SJ, Moriyama S, Francis GL, & Ballard FJ (1998). Evolution of insulin-like growth factor-I (IGF-I) action: in vitro characterization of vertebrate IGF-I proteins. Comparative biochemistry and physiology. Part B, Biochemistry & molecular biology, 121 (1), 35-41 PMID: 9972282
20. Mero A, Kähkönen J, Nykänen T, Parviainen T, Jokinen I, Takala T, Nikula T, Rasi S, & Leppäluoto J (2002). IGF-I, IgA, and IgG responses to bovine colostrum supplementation during training. Journal of applied physiology (Bethesda, Md. : 1985), 93 (2), 732-9 PMID: 12133885
21. Food and Drug Administration Center for Veterinary Medicine. Guidance for industry: Regulation of genetically engineered animals containing heritable recombinant DNA constructs. (2009).
22. Fleming, I. (1996). Reproductive strategies of Atlantic salmon: ecology and evolution Reviews in Fish Biology and Fisheries, 6 (4), 379-416 DOI: 10.1007/BF00164323
23. Bartley DM, Rana K, Immink AJ (2001). The use of inter-specific hybrids in aquaculture and fisheries. Reviews in Fish Biology and Fisheries 10:325-337.
24. Fraser DJ, Houde AL, Debes PV, O’Reilly P, Eddington JD, & Hutchings JA (2010). Consequences of farmed-wild hybridization across divergent wild populations and multiple traits in salmon. Ecological applications : a publication of the Ecological Society of America, 20 (4), 935-53 PMID: 20597281

Editor’s note

On September 19 and 20, 2010, the Veterinary Medicine Advisory Committee of the US Food and Drug Administration convened two days of meetings intended to 1) orient participants on the scientific issues and regulatory constraints, and 2) consider issues regarding the safety and effectiveness of the new animal drug application concerning AquAdvantage salmon produced by AquaBounty Technologies, Inc. At the close of the meeting, the committee chairman reported that the majority of the expert panel concluded that the AquAdvantage salmon is safe; however, they recommended further research to add weight in areas where the data is relatively sparse. Consumer protection organizations called for more research on the allergy risk of the AquAdvantage salmon.

Author’s note

You may have found it strange that Biofortified hadn’t covered genetically engineered salmon while various news sites, bloggers, and NGOs were writing about it practically constantly for a while there. All the while, an article was being written but getting down to the facts took a lot longer than those superficial stories you might have read. This was also my first time writing an article with an editor, my first time writing a solicited article, and my first time to receive payment for an article.

The article appears in a special edition of Information Systems for Biotechnology (ISB) News Report. ISB is a USDA funded project administered by the Agricultural Experiment Station at Virginia Tech.

From their website: “ISB provides information resources to support the environmentally responsible use of agricultural biotechnology products. Here you will find documents and searchable databases pertaining to the development, testing and regulatory review of genetically engineered (GE) plants, animals and microorganisms within the United States and abroad.”

It’s a great site, and the monthly newsletter contains some great articles. For example, check out September’s Newsletter for an article about cisgenics.

Many thanks to Ruth Irwin, Project Director of ISB, for her excellent editorial work which helped to produce a far better article than I would have done on my own. Ruth provided guidance without asking for any changes in content. This was a great learning experience.

This says to me that we are failing to counter misconceptions about genetic engineering and that we are failing to develop and deregulate traits that can be made available at low or no cost. What can we do to remedy the situation? Scientists can continue with research that is government funded and can continue to apply for grants to fund that research, even when the granting agencies are non-responsive. However, as the World Food Prize Laureates both pointed out, it takes more than scientists to help fight hunger. It takes individuals, and in the case of genetic engineering, it arguably takes partnerships with companies who are willing to help fund research as well.

Are we really committed to getting traits like water and nitrogen efficiency, improved nutrients, and insect protection out to the farmers who can use it, the farmers for whom even a small yield boost would make a big difference? If so, what can we do? Do we need more letter to the editor? More blog posts? More positive comments to the USDA to counter negative comments that were mobilized by anti agricultural technology organizations? More calls for companies to commit to helping small farmers? More scientist-advocates working to change public policy at the national level? What do you do, and what would you encourage others to do?

What substantial equivalence can do is give us a starting point.

We know that there is variation in amounts and types of proteins and metabolites, gene expression, and other parameters from variety to variety, from environment to environment, and from plant to plant. For example, if I use a microarray to find similarly and differently expressed genes in two genetically identical plants grown in slightly different environments, such as different temperatures, I will find some genes that have significantly different expression. Similarly, plants of different varieties grown in the same environment will have different gene expression profiles and even two identical plants in the same environment will have some differences.

The first step in a comparative assessment is to test and compare the genetically engineered variety to a genetically similar variety that doesn’t have the trans- or cis-gene. Tests can include gene expression, metabolic profiles, feeding studies, and more. If differences aren’t found in a reasonably wide panel of tests, then the genetically engineered variety can be called substantially equivalent to the genetically similar variety.

If differences are found, two questions need to be asked. First, does the change fall within the natural variation found among different varieties of the same species? For example, some varieties of corn with the Bt gene have been found to contain more lignin than genetically similar varieties without the Bt gene, but the amount of lignin falls within the normal range of lignin content for corn plants. Second, is there a scientific explanation for each change? For example, a transgene that causes higher calcium uptake from the soil is expected to result in higher amounts of calcium.

If there is a change that doesn’t fall within the natural variation for that species, especially if there isn’t an obvious scientific explanation for the change, then more testing needs to be done to determine safety with regard to environment and human health.

What substantial equivalence does not do is give license to make assumptions. The process of genetic engineering does have the potential to cause unintended changes in the resulting organism. That’s why a comparative assessment needs to be conducted before a plant, animal or microbe that has been genetically engineered can be deemed substantially equivalent to a non-genetically engineered but genetically similar organism.

One major problem with determining substantial equivalence is that it is hard to know which tests are appropriate. This problem has improved greatly as “omics” type tests have become more widely used. Tests for macronutrient content could be expected to miss small but significant changes but wide screens for changes in the transcriptome, proteome, or metabolome could be expected to find those small changes.

The metabolome seems to hold the most promise because it effectively tests the end product of gene expression and enzyme activity. Owen Hoekenga presented metabolomics in an excellent 2008 paper as a method that could be used to help determine substantial equivalence.

Hoekenga OA (2008). Using metabolomics to estimate unintended effects in transgenic crop plants: problems, promises, and opportunities. Journal of biomolecular techniques : JBT, 19 (3), 159-66 PMID: 19137102.

Abstract:  Transgenic crops are widespread in some countries and sectors of the agro-economy, but are also highly contentious. Proponents of transgenic crop improvement often cite the “substantial equivalence” of transgenic crops to the their nontransgenic parents and sibling varieties. Opponents of transgenic crop improvement dismiss the substantial equivalence standard as being without statistical basis and emphasize the possible unintended effects to food quality and composition due to genetic transformation. Systems biology approaches should help consumers, regulators, and other stakeholders make better decisions regarding transgenic crop improvement by characterizing the composition of conventional and transgenically improved crop species and products. In particular, metabolomic profiling via mass spectrometry and nuclear magnetic resonance can make broad and deep assessments of food quality and content. The metabolome observed in a transgenic variety can then be assessed relative to the consumer and regulator accepted phenotypic range observed among conventional varieties. I briefly discuss both targeted (closed architecture) and nontargeted (open architecture) metabolomics with respect to the transgenic crop debate and highlight several challenges to the field. While most experimental examples come from tomato (Solanum lycoperiscum), analytical methods from all of systems biology are discussed.

“Omics” studies that have been conducted on the substantial equivalence of genetically engineered plants to their non-genetically engineered counterparts have found that there are differences but those differences fall within the range of differences found within different varieties of the same species. Below are some such studies.

Kogel KH, Voll LM, Schäfer P, Jansen C, Wu Y, Langen G, Imani J, Hofmann J, Schmiedl A, Sonnewald S, von Wettstein D, Cook RJ, & Sonnewald U (2010). Transcriptome and metabolome profiling of field-grown transgenic barley lack induced differences but show cultivar-specific variances. PNAS, 107 (14), 6198-203 PMID: 20308540

Baker JM, Hawkins ND, Ward JL, Lovegrove A, Napier JA, Shewry PR, & Beale MH (2006). A metabolomic study of substantial equivalence of field-grown genetically modified wheat. Plant biotechnology journal, 4 (4), 381-92 PMID: 17177804

Coll A, Nadal A, Collado R, Capellades G, Messeguer J, Melé E, Palaudelmàs M, & Pla M (2009). Gene expression profiles of MON810 and comparable non-GM maize varieties cultured in the field are more similar than are those of conventional lines. Transgenic research, 18 (5), 801-8 PMID: 19396622

Lehesranta SJ, Davies HV, Shepherd LV, Nunan N, McNicol JW, Auriola S, Koistinen KM, Suomalainen S, Kokko HI, & Kärenlampi SO (2005). Comparison of tuber proteomes of potato varieties, landraces, and genetically modified lines. Plant physiology, 138 (3), 1690-9 PMID: 15951487

Gregersen PL, Brinch-Pedersen H, & Holm PB (2005). A microarray-based comparative analysis of gene expression profiles during grain development in transgenic and wild type wheat. Transgenic research, 14 (6), 887-905 PMID: 16315094

Another problem with comparative assessments is that each genetically engineered trait may require different types of testing, depending on what the trait is. For example, a drought tolerant crop may need to be tested under wet and dry conditions while a nutritional trait may not need to be tested under different environmental conditions.

An alternative view to substantial equivalence and comparative assessment is the precautionary principle. Instead of starting  by looking for differences between a genetically engineered organism and a non-genetically engineered but genetically similar organism as we find in a comparative assessment, the precautionary principle requires us to start with the assumption that there are differences and enough studies must be conducted to determine that something is completely safe before release. The precautionary principle is an important enough idea that it deserves its own post, but I will say here that it has some problems, the biggest of which is that the amount of testing that is deemed to be “enough” is rarely defined, so the amount of tests that “need” to be conducted can always be made larger, which may actually be the point.

New ways of looking at agriculture

Analytical frameworks can be helpful in putting peoples’ ideas about agriculture, and indeed many other things, into context. In “Integrating Sustainability into Agricultural Education”,  Wals and Bawden (2005, p. 30-32) describe dichotomous ways to see the world. Academics like Wals and Bawden and their predecessors and successors invent and use analytical frameworks to help describe ways of thinking. These frameworks, based on philosophical theory, are artificial divisions. No single one of them is “right” or “correct”, they’re just different ways to describe the same things. Nonetheless, it can be very helpful to categorize the ways that people frame the world around them. If we work to understand the frameworks that people use to view agricultural problems and solutions, we might be better able to communicate with people that have frameworks that differ from our own. Improved communication and collaboration between academics and activists, scientists and farmers in sustainable and conventional agriculture would be of great use to each person involved, to consumers, and to the environment.

While understanding these conceptual divisions can be very helpful, they are also holding each of us back. In order to achieve truly sustainable agriculture, we must all learn how to look past the frameworks that we impose on ourselves and look for ways that nature can guide us instead. For example, conventional farmers are often unwilling to make changes that might make their farms more sustainable. Part of the resistance is financial, because some changes require the purchase of new equipment, but part of the resistance is also emotional and tied to the mental frameworks that they have about agriculture. Similarly, organic farmers and other non-conventional farmers are more likely to take advice from non-conventional sources because their mental frameworks are often quite different from those of conventional sources such as extension agents (Eckert, 2005).

In this paper, I will examine two sets of opposing frameworks as described by Wals and Bawden (2005, p. 30-32): relativism and objectivism, and holism and reductionism. Specifically, I’ll apply these frameworks to agriculture, with the goal of showing that a better understanding of how these concepts frame our thinking and the thinking of those around us might result in a better, more sustainable, agriculture. Finally, I’ll show how better understanding of the different frameworks people might have towards a specific method can affect whether the method is considered sustainable.

Relativism and Objectivism: How do we know what we know?

Relativism and objectivism are both epistemologies, or ways of knowing knowledge. In the case of agriculture, the knowledge in question is knowledge of nature. Relativism is the idea that we understand reality only in the context of our own consciousness (Wals and Bawden, 2005). Taken a step further, relativism is a way of knowing that depends on our past or current experiences, and that depends on things that we are made aware of through our own senses. Objectivism is the idea that reality exists and can be understood separately from our own consciousness (Wals and Bawden, 2005).  In other words, knowledge in an objectivist epistemology contains universal truths that are unaffected by our personal experiences or sensory input, even though these are often the methods through which we understand reality.

Epistemology is closely related to methodology, the methods we use to gain knowledge about the world around us (Trochim, 2006a). In agriculture, there are many ways, or methods, to gain knowledge about a farm. Soil quality can be determined by feeling its texture in your hand and smelling its earthy richness. Its quality could also be determined by collecting soil samples and sending them to a lab to have various properties analyzed. The well-being of animals can be measured by how many offspring they produce. Their well-being can also be determined by how friendly they are, or by how frequently they play with their siblings. These different methods of gaining knowledge may be characterized as either qualitative or quantitative.
Qualitative methods look at a phenomenon in its greater context while quantitative methods examine distinct parts of a phenomenon (Trochim, 2006b). In many ways, qualitative methods depend on a relativist worldview; a qualitative researcher may become immersed in the phenomenon of study, examining a phenomenon through their own experiences and senses. Quantitative methods and researchers are more aligned with an objectivist worldview, in that they begin with the assumption that there is an ultimate reality that may be broken down into parts and studied. An example within agriculture might be the study of agricultural workers on different types of farms. A qualitative study might examine in depth the life histories of selected groups of workers and use this information to tell a story about their working conditions within the greater context of the workers’ lives. A quantitative study might involve a questionnaire that asked employers of farm workers to report quantitative characters, such as how many employees they have, how much the employees are paid, and so on.

Relativism, as in contextual and personal ways of knowing, and qualitative study, as in information gathering that considers the larger system, are generally associated with sustainable agriculture. Meadows explains her idea of relativism, which she calls systems thinking, as an acknowledgement of the uncertainty inherent in systems. An objectivist point of view implies that all knowledge is knowable, if we know how to measure it. Uncertainty is simply due to inaccuracy in measurement. The relativist point of view, on the other hand, implies that there is no essential knowledge to know, because reality is always changing based on the context in which we view things. This changing, or dancing, as Meadows calls it, can only be examined through flexible models that are constantly redesigned as the system changes.

Holism and Reductionism: What is the Nature of Nature?

Along with epistemology, ontology can provide useful distinctions in the way we frame the world around us (Wals and Bawden, 2005). Ontology is the study of the nature of reality, including the ways that reality might be divided or grouped. A holist perspective claims that an entity (concept, phenomenon, process, etc.) can not be divided into parts. If an entity is divided into parts, those parts do not in sum have all the properties that existed in the whole entity. Properties that are present in the entity but not in the parts are called emergent properties. A reductionist perspective claims that an entity can be divided into parts and that the properties of an entity are simply the sum of the properties of the parts.

Sustainable agriculture is generally considered to be holistic in that it considers whole entities.  Leopold (1949), one of the most well known figures in sustainable agriculture, shares his opinion of holism and reductionism in his allegory “Thinking like a Mountain”. Reductionist thinking led many states to enact programs to remove wolves from hunting ranges in an effort to encourage larger deer herds. The result was too-large herds that overgrazed the land to the point that it would no longer sustain deer. Leopold (1949, p. 132) says of the situation that man “has not learned to think like a mountain. Hence we have dustbowls, and rivers washing the future into the sea.” Instead of this reductionist thinking, sustainable agriculture would encourage holist thinking that includes the soil, foliage, deer, and wolves as part of the entity that is the mountain’s ecosystem. Any desired changes to the system must work with the system in its entirety. This holism in sustainable agriculture lends itself well to interdisciplinary study. One can not effectively consider the workings of an entire system by examining only one part of it.
Conventional agriculture is often associated with productionism, a form of reductionism. Productionist agriculture focuses exclusively on yield, and improvements in yield are achieved by manipulation of individual factors within an agricultural system. Individual changes within the system have been extremely successful in increasing agricultural production.  Increased yields were “driven by technological developments in five areas: increased use of chemical fertilizers; high-yield crop varieties with a stronger response to those fertilizers; chemical pesticides for controlling insects, weeds, and diseases that depressed yields; greater use of irrigation; and increased mechanization” (Phelan, 2009, p. 2). Reductionism in agriculture does not require interdisciplinary work except at the most shallow level. It is typical for conventional agricultural research to focus on a narrow subject area within one discipline. Phelan (2009, p. 4) states that reductionism in agriculture “is reflected in the structure of agricultural colleges of U.S. and European universities, which are almost universally divided into disciplines, if not departments, of soil science, agronomy, horticulture, weed science, entomology, and plant pathology.”

Defining Sustainability: Using frameworks to describe what we mean

Understanding the analytical frameworks of relativism and objectivism and holism and reductionism can help us to better communicate about sustainability. Keller and Brummer (2002), Leibman et. al (2008), and many others make a case for moving conventional agriculture away from objectivist and reductionist thinking and towards relativist and holist thinking. I agree, and humbly suggest that sustainable agriculture must meet conventional agriculture somewhere in the middle, if not for any other reason than the fact that an entirely relativist or entirely holist frame makes it difficult to communicate with the objectivists and reductionists that make up the majority of farmers and agricultural researchers.

We may be better able to achieve a more sustainable agriculture if we recognize that both relativist/qualitative/holist/interdisciplinary and objectivist/quantitative/reductionist/individual ways of knowing, measuring, and studying are valuable. In fact, these ideas are most useful in combination. We must at minimum work to understand views that are different from our own. Doing so will allow us to communicate with more people that have diverse viewpoints. It will allow us to understand information that is collected in ways that are different from the ones we are used to, and potentially allow us to use these different methods in our own exploration of the reality that is a farm. It will also help us to evaluate farming methods to determine if each has a role to play in sustainable agriculture.

However, we must be careful to not give too much weight to epistemological or ontological distinctions. In practice, there are few if any farmers or agricultural researchers that apply any of the frames to exclusion of the others. There is no such thing as “sustainable farming” or as “conventional farming” if we define them as “holistic farming” and “reductionist farming” respectively. In reality, there is a gradient between particularly sustainable/holistic methods and particularly conventional/reductionist farming methods, with many methods in-between. Even the most reductionist farmer uses some practices that rely on the farm as an ecological system to achieve a goal. Crop rotation and cover crops are both methods that are associated with sustainability and a holist way of thinking about agriculture, but they are used by conventional farmers to some degree, and the majority of conventional farmers are interested in adopting these methods (Singer and Nusser, 2007). Similarly, a truly holistic farmer shouldn’t make any individual responses to specific problems, instead they should modify the system as a whole. All good farmers, sustainable or otherwise, carefully observe their fields and react as needed, whether their reactions include are synthetic nitrogen and organophosphates, or blood meal and neem. All of these are reductionist responses, though the second two consider secondary effects within the system more than the first two.  A more holistic farming system can be achieved, but not a truly holistic farming system. The key to a more sustainable, if not more holistic, agriculture is to evaluate each method individually on its own merits. In short, we can use the analytical frameworks as a guide, as long as we don’t use them dogmatically.

Bringing the Concepts together: Does Biotechnology have a role in sustainable agriculture?

It has been argued that biotechnology is just one more reductionist solution in the body of reductionist solutions that make up conventional agriculture. Krimsky (2005) argues that the reductionism in biotechnology began in 1975 and has not changed since. This is true of some traits created with biotechnology, but other traits can be seen as providing a solution that works within the greater context of the system. Conventional agriculture faces its biggest problems when looking outside of systems for solutions to problems within the system. Ronald and Adamchak (2008) argue that biotechnology is inherently compatible with sustainable farming because biotechnology allows us to find biological solutions for biological problems. Synthetic pesticides and fertilizers are chemical solutions for biological problems, and many of these have significant unintended effects both inside and outside of the system. Traits like herbicide resistance do not work with biology to solve problems because they encourage chemical use, even though they may encourage farmers to use a less toxic herbicide than the ones currently in use. Upcoming traits like drought tolerance, nitrogen use efficiency, and so on are reductionist in nature, because they address individual problems like scarcity of water and nitrogen runoff. However, these traits allow a farmer to reduce other inputs into the system which is a major goal of sustainable agriculture.

In my own research, I am developing nutritionally enhanced crops through breeding and biotechnology. Some traits are best manipulated with selection while other traits are best introduced with biotechnology. Each is a tool that can be used to achieve goals that may or may not fit into the different analytical frameworks. The nutritional quality of crops is in itself a reductionist goal. Krimsky (2005, p. 322) sums up his pessimistic view of biotechnology thusly: “rather than seeing the problem of vitamin A deficiency in terms of loss of crop bio-diversity, poor access to seeds, water resources, farming machinery, and arable land, it is seen as one of nature’s failings, namely that its rice lacks beta carotene – something that can be easily fixed through biotechnology and provided through a global seed cartel.” This view is only accurate if the analytical frameworks are kept rigid. In reality, the frameworks are flexible and we may find a variety of solutions that are appropriate for a given system. Few, if any, proponents of biotechnology would embrace a solution to nutritional deficiency that includes only biotech crops. Instead, proponents would suggest nutritionally enhanced crops that fit in the current system, but only in combination with solutions that would improve the system overall, such as poverty reduction. Each solution, whether holist or reductionist, relativist or objectivist in nature, may be part of a more sustainable agriculture, if only we are able creatively view the merits and faults of each solution in the context in which it will be applied.

Works Cited

Eckert, Eileen and Alexandra Bell. (2005) Invisible force: Farmers’ mental models and how they influence learning and actions. Journal of Extension Vol. 43 No. 3.

Keller, David R. and E. Charles Brummer. (2002) Putting Food Production in Context: Toward a Postmechanistic Agricultural Ethic. BioScience Vol. 52 No. 3.

Krimsky, Sheldon. (2005) From Asilomar to industrial biotechnology: Risks, reductionism and regulation. Science as Culture Vol. 14 No. 4.

Liebman, Matt, Fred Kirschenmann, Rich Pirog, and Jerry DeWitt. (2008) Sustainable agriculture in the United States: Maturation and new directions.

Leopold, Aldo. (1949) Thinking Like a Mountain. A Sand County almanac: And sketches here and there. Oxford University Press.

Meadows, Donella. Dancing with systems.

Phelan, P. Larry. (2009) Ecology-based agriculture and the next green revolution: Is modern agriculture exempt from the laws of ecology? Agroecosystem management for ecological, social, and economic stability. CRC Press.

Ronald, Pamela and Raoul Adamchak. (2008) Tomorrow’s table: Organic farming, genetics, and the future of food. Oxford University Press.

Singer, J. W. and S. M. Nusser. Are cover crops being used in the US corn belt? Journal of Soil and Water Conservation Vol. 62 Issue 5.

Trochim, William M. K. (2006a) Positivism and post-positivism.

Trochim, William M. K. (2006b) The qualitative-quantitative debate.

Wals, Arjen E. J. and Richard Bawden. (2005) Part 1: Integrating sustainability into agricultural education; Dealing with complexity, uncertainty, and diverging worldviews. Curriculum innovations on higher education. Elsevier Overheid: The Hague, Netherlands.

Let’s take Research Shines Light on Gulf of Mexico Hypoxic Zone (full paper) as an example. This report by the National Corn Growers association was, to be blunt, biased to the point of falsehood. I explain how in Rotten Corn. The organization has an agenda to put corn farming practices in the best possible light, which means every report we see from them will have some degree of spin. We should expect some degree of spin from any of these groups, but sometimes they overstep the line.

Spin can be frustrating, particularly when we have specific evidence that contradicts what the special interest group said. What happens when the bias isn’t as obvious as in the NCG’s hypoxia report? Sometimes these reports seem 100% legitimate, especially when we agree with the agenda of the group, and especially when we don’t have the prerequisite knowledge to judge them. Even worse, there are many situations where two groups will put out directly opposing reports. Each group claims to have the “real” information, sometimes even calling out opposing reports.

The most recent example of this is the Organic Center’s Impacts of Genetically Engineered Crops on Pesticide Use: The First Thirteen Years. It directly contradicts the year old GM crops: global socio-economic and environmental impacts 1996- 2006 (pdf) by PG Economics. I covered some of the specific differences in Does using GMOs really increase pesticide use? a few days ago. In researching for the post, I made the decision to include the PG Economics report as an opposing viewpoint because the sources of the data are solid and the conclusions they make in the paper are well supported by peer-reviewed research. The Organic Center’s report leaves out a lot of data that is readily available, and doesn’t explain why – which is enough to make me question the conclusions in the report (along with glaring problems like lumping all biotech traits as “GMOs” with only a passing mention of how Bt and glyphosate resistant crops are different).

I mention these two opposing reports on GMOs and pesticide use to show that it is possible to evaluate “spun” reports when we consider them with a critical eye and a reasonable familiarity with peer-reviewed research on the subject. Why peer-reviewed? To paraphrase Winston Churchill, “Peer review is the worst form of quality control for scientific research except for all those others that have been tried.” Mistakes do, famously, get through, but don’t matter as they are either ignored (not cited by other scientists) or directly contradicted by new research.

These reports, scientifically sound or not, bypass the peer-review process. They aren’t screened by other scientists before they are published, and sometimes they are written by people who aren’t even in the field they are writing about. They can be good sources of information, but only if we take it to the next level and seek out the peer-reviewed research behind the reports as well as opposing viewpoints to help us get the big picture.

52 card pickup by mikep, via flickr.

When I say peer-reviewed research, I’m not just talking about one paper. Instead, I mean multiple papers, preferably by different authors from different institutions, and different funding agencies. The papers should use different data sets and different experimental designs that ask similar questions.

Imagine that the entire body of peer-reviewed research for a subject area is a deck of cards that we’ve placed on the table, 52 card pickup style. Each card is a paper that is related to some of the other papers. Some papers cover very similar areas, totally overlapping. Others are only slightly related, with just a tip overlapping. Any one of those cards won’t tell us that much about what’s really happening, but when we look at the whole pile, particularly the overlapping areas, we can start to understand what’s really happening.

For more on the benefits and downfalls of peer review, see Nature’s peer review debate (accessible without login!).

First, all GMOs are not created equal. The two biotech traits currently on the market are herbicide tolerance and insect resistance (Bt). These traits are obviously very different, but most of the report just lumps them together as “GE crops”, even though the report clearly states multiple times that Bt crops have reduced insecticide use. For example:

Bt corn and cotton have delivered consistent reductions in insecticide use totaling 64.2 million pounds over the 13 years. Bt corn reduced insecticide use by 32.6 million pounds, or by about 0.1 pound per acre. Bt cotton reduced insecticide use by 31.6 million pounds, or about 0.4 pounds per acre planted.

Why, then, does the report fail to distinguish between glyphosate tolerant crops and Bt crops when concluding:

For the foreseeable future, this study confirms that one direct and predictable outcome of the planting of GE corn, soybean, and cotton seed will be steady, annual increases in the pounds of herbicides applied per acre across close to one-half the nation’s cultivated cropland base. Farm production costs and environmental and health risks will rise in step with the total pounds of pesticides applied on GE crops.

What about Bt crops? What about nitrogen efficient crops? What about nutritionally enhanced crops? These don’t require additional pesticides of any kind when compared to non-biotech crops. If anything, the conclusion should read:

…this study confirms that one direct and predictable outcome of the planting of herbicide tolerant corn, soybean, and cotton seed will be steady, annual increases in the pounds of herbicides applied per acre across close to one-half the nation’s cultivated cropland base. Farm production costs and environmental and health risks will rise in step with the total pounds of herbicides applied on herbicide tolerant crops.

Second, all pesticides are not created equal. There are huge differences between pesticides in toxcicity, target organisms, amount required, etc. Use of glyphosate, the active ingredient in RoundUp herbicide, certainly does increase with glyphosate tolerant crops. The million dollar question is: does the use of glyphosate replace the use of other herbicides? And even more importantly, what is the relative impact of the herbicides used? The Organic Center’s report doesn’t actually address these questions.

The 2008 report GM crops: global socio-economic and environmental impacts 1996- 2006 (pdf) produced by PG Economics did answer these questions*. They used an index called EIQ (Environmental Impact Quotient) which was first described by Kovach et al in 1992 (to learn exactly how the EIQ is calculated, see the American Farmland Trust’s explanation). The EIQ actually factors in how toxic a pesticide is as well as how much active ingredient is used. This report found (on page 60-61) that, in soybeans, the global impact has been:

In 2006, a 6% decrease in the total volume of herbicide [active ingredient] applied (10.1 million kg) and a 23.7% reduction in the environmental impact (measured in terms of the field EIQ/ha load)

Since 1996, 4.4% less herbicide [active ingredient] has been used (62 million kg) and the environmental impact applied to the soybean crop has fallen by 20.4%.

A similar global impact was seen in maize:

In 2006, total herbicide ai use was 8.3% lower (10.9 million kg) than the level of use if the total crop had been planted to conventional non GM (HT) varieties. The EIQ load was also lower by 10.8%

Cumulatively since 1997, the volume of herbicide ai applied is 3.9% lower than its conventional equivalent (a saving of 46.7 million kg). The EIQ load has been reduced by 4.6%.

It certainly seems strange that two different reports would have such vastly different conclusions.

Third, what about non-biotech herbicide tolerant crops? Breeding for herbicide tolerance doens’t require biotechnology at all – breeders can simply rely on artificial selection (aka “natural” plant breeding). For example, consider the Clearfield trait, resistance to the herbicide imidazoline. Clearfield is available in far more crops than glyphosate resistance, likely because it is not required to undergo any of the additional testing or regualatory hoops that are required for biotech traits. Crops available with Clearfield include sunflower, canola, corn, wheat, and rice. Because this is a non-biotech (non-transgenic, non-GMO) herbicide resistance trait, Clearfield crops aren’t tracked in the same way as Roundup Ready crops.

“This report deals only with GE HT crops” even though “a market research firm recently estimated that non-GE herbicide-resistant crops were planted on roughly 6 million acres in 2007.” The thing is, if biotech herbicide tolerance was never invented, we’d just have many more acres of non-biotech herbicide tolerance. Using herbicide tolerant non-GE crops would result in all of the same effects that we see in GE herbicide tolerant crops. Additionally, improper use of herbicides of any type (in conjunction with herbicide tolerant crops or not) will result in resistant weeds. It is misleading to claim that side effects of herbicide use are due to genetic engineering.

If a person was truly interested in determining how novel traits affect herbicide use, that person would consider all types of herbicide resistance, instead of singling out just the ones created with a certain method.

In sum, these are the three main complaints I have with this report: failure to distinguish between different biotech traits, failure to distinguish between different pesticides, and failure to consider non-biotech traits that could increase pesticide use.

What are your thoughts?

*I already had a copy of the PG Economics report stored in Papers (iTunes for journal articles), but when I went to find the link for this post, I found that PG Economics has actually written their own rebuttal to the Organic Center’s report: Impact of genetically engineered crops on pesticide use: US Organic Center report evaluation by PG Economics (pdf). They cover far more specific issues than I did in this post – I recommend it and the original PG Economics report as a counterpoint to the Organic Center report. No matter our personal beliefs, it’s always good to expose ourselves to many points of view.

Another viewpoint can be found at Truth About Trade and Technology, a non-profit farmer’s advocay group, where Illinois farmer John Reifsteck wrote The Business of Farming in response to the Organic Center’s report.