Editorial Summary of the National Academy of Science’s Consensus Report on Genetically Engineered Foods

This morning, the National Academy of Sciences (NAS) released a consensus report titled “Genetically Engineered (GE) Crops: Experiences & Prospects”. You can download the full 400 page report which includes a four page summary here. The public release of the report was accompanied by a webcast including a presentation of the report followed by a question and answer session. My notes on the webcast including screen shots of many of the slides are synthesized below. I apologize for any missing slides or points. None were omitted intentionally. As a scientist, I tended to focus my notes more on human health and the environment and less on social/economic points.

The NAS is a private, non-profit organization that “is charged with providing independent, objective advice to the nation on matters related to science and technology. Scientists are elected by their peers to membership in the NAS for outstanding contributions to research. “

Volunteers for the NAS committee to assemble the consensus report were vetted for potential conflicts of interest. The committee was composed of a very diverse range of scientists and experts from a variety of different topic areas ranging from entomology to science communication. The committee was initially divided, as there were many different views on the prospects and progress of genetically engineered crops. However, all members were required to back their claims with evidence as the discussion progressed, and they ultimately came to a consensus that best reflects the available data.


In analyzing the issue, the committee looked to two decades of scientific literature including nearly 1000 articles. They also listened to input from 80 diverse speakers, and reviewed over 700 public comments. These videos and other materials have all been archived and are publicly available. The study was sponsored by the New Venture Fund, the Gordon and Betty Moore Foundation, the Burroughs Wellcome Fund, the U.S. Department of Agriculture, and the National Academy of Sciences. The report had 26 diverse reviewers. The committee had to respond to each of their comments and defend their conclusions with evidence.

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The first key message from the committee emphasized the increasing difficulty of differentiating crop improvement technologies that qualify as GE from those that do not (you can read my personal explanation of this issue here). The chair of the committee Dr. Fred Gould likened this to the invention of cell-phones, cameras, and lap-tops which were once all distinct technologies that now have overlapping functions.


For this reason, the committee contends that it is impossible to “make sweeping generalizations about the benefits and risks of GE crops”. For the report, they mainly focused on three of the most widely grown GE crops: corn, cotton, and soybeans. The report also focused on the two most commonly utilized traits: insect (BT crops) and herbicide (RoundUp-Ready crops) resistance.

The committee generally concluded that insect resistant crops result in increased yields due to fewer losses from pests. Planting of insect resistant crops also correlates with a decrease in the application of synthetic pesticides and an increase in biodiversity. However, improper management of insect-resistant crops can and has resulted in the evolution of resistant insects.

insect resistance

They also concluded that the planting of herbicide-resistant crops can lead to an increase in yield. Beyond yield, the technology is substantially useful to farmers for several reasons. Herbicide-resistant crops allow farmers to apply a single herbicide where they might before have used many at a time when it is optimally convenient, safe, and physiologically advantageous for their crops.


My screenshot of this slide did not turn out, so I looked it up in the archives

The committee also notes that weeds (like the insects) have evolved resistance to this herbicide creating a huge challenge for farmers who will need to change their management strategies. The committee also made a point to emphasize that comparisons of kilograms of herbicide use before and after herbicide-resistant crops were widely adopted is not meaningful unless the health and environmental impacts of those herbicides are also compared.

herbicides 2

The committee’s analysis of the environmental impact of GMOs, revealed some evidence of gene flow from GE crops into wild ecotypes, but only under experimental conditions. The committee in general found that there was no evidence of environmental problems caused by growing GE crops. There was also no direct connection between the use of herbicide-resistance crops and no-till practices as farmers had already begun to move away from tilling prior to the advent of GE crops.


In response to the question of whether or not GMO crops are contributing to yield increases, the committee contends that they are. They acknowledge that what’s good for one farmer is not good for another, but farmers in general are gaining from the technology.

yield rate

That said, as these graphs show, there is not a spike in yield increase following the advent of GE crops (indicated by the vertical purple line). This likely demonstrates that changes in management practices and genetics through conventional breeding and other crop genetic improvement methods are equally as important for increasing crop yield. New types of GE crops could potentially contribute to the rate of increase depending on the traits introduced and the socioeconomic/cultural/legal factors that influence the adoption of new GE crops.

yield 2

To assess the impacts of GE crops on human health, the committee analyzed over 200 existing studies, looked for changes in patterns of human health before and after the adoption of GE foods, and compared the overall health of people in the United States and Canada (where GE crops are widely grown) with the health of people in Europe (where they are not). The committee reported that many of the existing animal studies were not optimally designed.

human health 1

Reports of long-term health of livestock fed GE diets and studies comparing nutrient and chemical compositions of GE food were more reliable. From these, they did not find any reliable evidence linking GE foods to health concerns. They also did not find any differences in human health that correlated with the adoption of GE crops.

human health 2

Given the lack of legitimate health concerns associated with GE foods in general, the NAS proposed a new system for regulating future GE foods. The proposed regulatory approach would compare the “omics” (levels of various compounds including nucleic acids, proteins, and metabolites) of new crops with the same levels in existing varieties.

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New crops would then be categorized as Tier 1 if there are no differences or Tier 2 if there are differences that have no expected health or environmental effects. Tier 1 or 2 crops would not require any further testing. If the new crops have differences with potential for health or environmental effects or differences that cannot be interpreted, they would be classified as Tier 3 or Tier 4 respectively and would require further testing. Under this system, most new varieties would fall under the category of Tier 1 or Tier 2.


On the issue of labeling, the committee concluded that because there are no health effects associated with GE food, there is no justification for labeling them on the basis of food safety. There are, however, policy reasons for which labels might be instituted such as consumer autonomy. It is outside of the legal authority of the FDA to institute a label for policy/cultural reasons, so labels would need to be mandated at the congressional level.

Read what a handful of other academic scientists had to say about the report here.


What’s everyone’s beef with beef?

I grew up on a cattle ranch, which means I ate beef for every meal. My plates included parts of a cow that would make most readers blush. Chicken might as well have been a vegetable.

When I left rural eastern Colorado, I was surprised to meet people who considered my family’s beef dependance not only unusual but also unethical. My college roommate, who also moved to Boulder from a cattle ranch, actually had tofu thrown at her because she wasn’t a vegetarian. Even the meat-eaters  insisted on purchasing only grass-fed, organic beef. Talk about a culture shock.

The reasons for animosity towards omnivores range from trendiness to animal welfare, but often included an argument that meat-consumption is less environmentally friendly. There are at least two reasons cited for this. For one, the calorie conversion by animals, particularly cows, is not very efficient. That is, we get more calories out of eating the corn that a cow would eat than by eating the cow. Additionally, cows and other ruminants literally burp greenhouse gases (GHGs).

As I read an NPR article about cow belches, I found myself wondering whether adjusting the cow’s diet would reduce emissions. If rumination leads to GHG emissions, might strictly grass-fed cows be less environmentally friendly since they ruminate more? To find out, I took to twitter, and asked Amy Young, a staff research associate in a beef cattle genomics and biotechnology lab at UC Davis.

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Amy responded with an extensive review of research comparing the carbon footprint of different protein sources, as well as a reader-friendly synthesis of these and other data into a consumer info handout by the primary investigator in Amy’s lab, Dr. Alison Van Eenennaam.

The simple answer to my question provided by these data is yes, cows on a strictly grass-fed diet produce more GHGs; however, the reasons behind my prediction might not be correct. Grass-fed beef, when compared with intensively raised, corn-fattened beef, have a higher emission to protein ratio because they spend more of their life out walking around burning off calories. Strictly range-fed beef take longer to get to market weight, which means more time spent burping methane.

But the issue gets more complicated. For cows fed corn, the environmental impact of growing the corn has to be taken account. If the cows are pasture grazed, then what type of pasture? If the cows feed on dry grasslands not useful for farming, and only eat forage, then there is no loss in terms of land use or wasted calories. But for cows fed on irrigated pasture as many of the happy cows in California are, water use has to be considered. And cows that live in colder states have to be fed bailed hay during the winter to qualify as grass-fed, which means farmland that could be used to grow food is growing feed.

Confused yet? Me too, but the major take home message is simple. There’s a huge range of environmental impact for beef depending on where/when/what/and how they’re fed. The same is true of every single prospective protein source, flora or fauna. Dr. Van Eenennaam summarizes this concept beautifully:

There is no one sustainable source of protein, and depending upon the question that is being asked (e.g. carbon emissions/water use/land use/energy use per calorie/unit weight/unit protein), different food products will look like the “most sustainable” choice. There are also ethical and religious concerns around animal welfare and/or consuming meat and/or animal products (e.g. eggs, milk). Often there are direct conflicts between what is perceived as the most sustainable production system. Is it the one that best protects animal health/welfare, the one with the lowest environmental footprint per unit of product, or the most efficient? As with all dietary decisions there are tradeoffs among the various pillars of sustainability, and consumers will need to make the choices they consider to be best for their particular family values, budget, and circumstances.”

When it comes to making environmentally conscious dietary decisions in the United States, possibly the most important point to remember is that, regardless of our specific diets, most American’s consume way more protein than they actually need. Perhaps instead of focusing so much on which particular food sources are the most environmentally friendly, we should try to remember that everything we eat has some impact on the environment. Restricting total calorie and protein intake to not surpass what is essential is probably the single clearest dietary step the average westerner can take to decrease their environmental footprint.

So you heard GMOs are banned in Europe…

The lowdown: The European Union has approved the cultivation of one GMO and importation of many (with more on the horizon). The European Commission and European Academies Science Advisory Council, like other government and scientific associations around the world, supports the evidence-based conclusion that GMOs currently on the market are not any less safe than  their conventionally bred counterparts. Nonetheless, certain member states within the EU have elected to ban cultivation of EU-approved GMOs on political/cultural grounds.

The details: Headlines claiming that GMOs are banned in Europe abound. These are often accompanied by an assertion that the United States should follow suit. Does the EU know something the US does not? Where are these claims coming from?

In response to the question “why are GMOs banned in other countries,” Dr. Robert Paarlberg, Professor of Political Science at Wellesley College and Adjunct Professor of Public Policy at the Harvard Kennedy School, clarified:

Very few countries explicitly ‘ban’ GMOs. In most cases, governments have simply not yet ‘approved’ various GMO crops for cultivation, or for import, or for human consumption. The presumption that each separate GMO should require case-by-case and use-by-use approval, by national government regulatory committees, has greatly slowed down the uptake of the technology. In effect, GMO foods and crops are being regulated as strictly as medical drugs, even though there is no evidence that they carry more risks than conventional foods and crops (in the official opinion of the EU Research Directorate, for example). Critics of GMO crops have promoted highly precautionary regulatory systems as one way to slow down the spread of the technology, and in large parts of the developing world governments have not yet given any cultivation approvals at all

As has been previously noted, Europe is not a unified country, but a continent made up of separate countries, many of which participate as member states in the coalitional European Union. The  EU as a whole has established directives regarding the import and cultivation of GMOs, and, like the US, requires pre-market safety testing and post-market environmental monitoring of GMOs. The EU has only authorized one crop for cultivation, pest-resistant Bt corn (Mon-810), however 58 GMOs have been approved for import as food and feed, and 58 more are awaiting regulatory approval. 17 of these have received a positive European Food Safety Authority (EFSA) assessment, and one is inconclusive. Applications for cultivation of 8 additional GMOs (including one renewal of Mon-810) are pending, and 4 have received a positive EFSA opinion.  Furthermore, the EU relies heavily on external sources for soymeal, and imports more than 60% of plant protein needs. 90% of these imports originate from countries where GE soybeans cover 90% of total soybean acreage.

Within the EU, member states can choose to ban the cultivation of GMOs that have been approved by the European Commission. Previously, a member state could elect to ban cultivation of approved GMOs only “if they had new evidence that the organism concerned constitutes a risk to human health or the environment or in the case of an emergency”. No such evidence has ever been presented. In response to a series of legal battles, the EU revised its guidelines to grant member states more freedom over decisions to ban GMO cultivation. Under the new (2015) directive:

a Member State may prohibit or restrict the cultivation of the crop based on grounds related amongst others to environmental or agricultural policy objectives, or other compelling grounds such as town and country-planning, land use, socio-economic impacts, co-existence and public policy.

Reluctance of some European countries to cultivate GMOs is often cited as evidence that European scientists and authorities are uncertain of their safety:

Washington wants Europe to ease restrictions on imports of these foods, commonly known as GMOs for genetically modified organisms, but the EU is skeptical they are safe.

However, according to an extensive European Commission Report on EU-funded GMO research:

The main conclusion to be drawn from the efforts of more than 130 research projects, covering a period of more than 25 years of research, and involving more than 500 independent research groups, is that biotechnology, and in particular GMOs, are not per se more risky than e.g. conventional plant breeding technologies.

Within the report, Marc Van Montague Chairman of the Institute of Plant Biotechnology for Developing Countries (IPBO) at Ghent University in Belgium goes on to say:

Now, after 25 years of field trials without evidence of harm, fears continue to trigger the Precautionary Principle. But Europeans need to abandon this knowingly one-sided stance and strike a balance between the advantages

Further, the European Academies Science Advisory Council has stated:

The scientific literature shows no compelling evidence to associate such crops, now cultivated worldwide for more than 15 years, with risks to the environment or with safety hazards for food and animal feed greater than might be expected from conventionally bred varieties of the same crop.

Despite approval of GMOs, much of the food in EU member-state grocery stores is GMO-free, because, according to the European Commission:

Many food business operators have made the choice of not placing GM food on the shelves. This may be linked to the labelling obligations of the GMO legal framework, as well as the availability of non-GM alternatives.


Here are a few other helpful resources on GMO regulation in the EU:

GMOs: EU decision-making process explained

Fact Sheet: Questions and Answers on EU’s policies on GMOs. April 22, 2015

A decade of EU-funded GMO research

European Academies Science Advisory Council: Planting the Future

A look at GMO policies in different nations. Layla Katiraee, July 6, 2015

Where are GMOs grown and banned? Genetic Literacy Project, Accessed April 27th, 2016


It’s the plants. They’re learning. They…remember


Sorry Mark Wahlberg, this is not a prequel to the 2008 sci-fi thriller “The Happening,” but maybe M. Night Shyamalan was onto something. Could plants learn that large groups of people are threatening, then kill them with an aerosol neurotoxin? Probably not. But they do learn, remember, forget, and even make decisions in some capacity.

If you’ve ever touched a mimosa pudica, the so-called sensitive plant, you know that plants can freak out. They sense a disturbance and react, possibly to protect themselves from hungry insects. Could they learn to tell the difference between threatening and non-threatening stimuli?

To find out, Dr. Monica Gangliano, associate professor in the school of animal sciences at the University of Western Australia, stimulated mimosa plants repeatedly with water droplets. After several showers, the plants stopped responding. Remarkably, months later, the same plants still didn’t recoil from a water droplet. The plants seemingly learned the water was not a threat, and remembered, even in the absence of stimuli.

These results are striking, but discoveries of learning and memory in plants are not new. Plants are exposed to a variety of stresses. Some are enduring like the cold of winter. Others are transient like heat stress in the late afternoon. Responding to stress requires energy, and often stalls growth. Thus it is beneficial for plants to remember and respond quickly to some stresses while learning to ignore others.

Plants have several strategies for recording memories and passing them on to future generations. In response to stress, plants can reorganize their DNA to activate or inactivate certain genes in a semi-permanent and heritable way. Plants can also store molecules of RNA, which act like molecular messages to enable a rapid response to future threats. A recent discovery by Dr. Susan Lindquist’s group at Massachusetts Institute of Technology suggests that plants may also store and transmit memories using proteins called prions

Prions are best known as the causal agent for mad cow disease (scrapies in sheep and Creutxfeldt-Jakob Disease in humans), but they are also associated with long-term memory storage in animals. Prions are able to adopt unique folding patterns. These patterns can be inherited and transmitted to neighboring proteins like a molecular switch that causes cascading and permanent changes.

Lindquist’s group used computational methods to look for genes in plants that resembled those encoding prion proteins in yeast. They then expressed the functional domain of what appeared to be a plant prion in yeast. The plant domain was able to functionally replace an analogous domain in a yeast prion protein. This strongly suggests that plants have prions or prion-like proteins.

Does this mean plants have brains, or plant neurobiology is the next big field of study? Doubtful. What some have called plant neurobiology is remarkably similar to what has always been recognized as stress response. To say that plants are making decisions probably gives them a bit too much credit. Decision-making is a more-or-less voluntary response. Plant reflexes might be a more appropriate term to describe the changes that occur in a plant in response to stress.

Nonetheless, similarities between plants and animals should not be ignored. Gangliano and Lindquist’s studies demonstrate the value of breaking down organism barriers in science. In the current structure, plant scientists go to plant science meetings, veterinary/livestock researchers go to animal meetings, and everyone else goes to meetings focused primarily on human health. Plants, humans, and other animals coexist in an interdependent web, so should our approaches to studying them.


S Chakrabortee, C Kayatekin, GA Newby, ML Mendillo, A Lancaster, S Lindquist. Luminidependens (LD) is an Arabidopsis protein with prion behavior..Proc Natl Acad Sci U S A , (2016).

PA Crisp, D Ganguly, SR Eichten, JO Borevitz, BJ Pogson. Reconsidering plant memory: Intersections between stress recovery, RNA turnover, and epigenetics.. Sci Adv 2, e1501340 (2016).

S Berry, C Dean. Environmental perception and epigenetic memory: mechanistic insight through FLC.. Plant J 83, 133-48 (2015).

M Gagliano, M Renton, M Depczynski, S Mancuso. Experience teaches plants to learn faster and forget slower in environments where it matters..Oecologia 175, 63-72 (2014).

So you heard GMOs cause “superweeds”….

The low down: Superweed is a misleading term used to describe weeds that are resistant to an herbicide. It is conceptually possible that certain, herbicide-resistant GMOs could contribute to an increase in herbicide-resistant weeds; however, such concerns are not limited to GMOs, but are relevant for any crops used in conjunction with herbicides.

The details:  First of all, what is a superweed? According to the Weed Science Society of America (WSAA), there is “no science-based definition for superweed,” but the term is often used to describe herbicide-resistant weeds.  Just as overuse of one particular antibiotic promotes the spread of bacteria resistant to that antibiotic, overuse of an herbicide can result in herbicide-resistant weeds. According to Rick Boydston of the USDA-ARS:

Resistance is a natural phenomenon which occurs spontaneously in weed populations, but is only noticed when a selection pressure is applied to the weeds via herbicide application

Boydston further explains that herbicide resistant plants within a given population of weeds are rare:  “1 in 100,000 to 1 in 1,000,000”. Treating this population with an herbicide provides selective pressure, so that only the few resistant plants naturally present in the population go on to produce the next generation, thus passing on the resistance trait.

Weed scientists like Dr. Andrew Kniss find use of the term superweed to describe herbicide-resistance “exceptionally frustrating” because it “indicates that the weed is super in some way”. However, despite claims that “Some runaway weeds in the southern U.S. are said to be big enough to stop combines dead in their tracks,” herbicide-resistant weeds are not any bigger or nastier than their non-resistant counterparts.

Anti-GMO activist groups like Food Integrity Now call herbicide-resistance “a direct result of growing GM crops”. Where do these claims come from?

There are two ways that specifically herbicide-tolerant GMOs could hypothetically contribute to a rise in herbicide-resistant weeds. It is important to note that not all GMOs are herbicide tolerant. The following points apply only to crops that have been genetically modified to tolerate the herbicide glyphosate. It has been proposed that herbicide-tolerant GMOs could contribute directly to the rise in herbicide-resistant weeds through cross-pollination with closely related weed species. This explanation is embodied in the oxford dictionary definition of a “superweed”:

A weed which is extremely resistant to herbicides, especially one created by the transfer of genes from genetically modified crops into wild plants

However, According to the WSAA, “The transfer of resistance traits from genetically modified crops to weeds growing in the field is rare.” And according to Dr. Brad Hanson, Cooperative extension specialist at UC Davis, “to date no herbicide-resistant weeds in corn, cotton, or soybean production regions appear to have become resistant due to traits moving from the crop.”

If GMOs did cross with weeds and pass on herbicide-tolerant traits, this problem would not be unique to GMOs, but could also result from crops that have been conventionally bred for herbicide resistance. For example, it is documented that imidazolinone-resistant jointed goat-grass arose from a cross-pollination event with wheat bred to tolerate imidazolinone.

Herbicide-tolerant GMOs could also contribute to the rise in herbicide-tolerant weeds indirectly by encouraging an increase in the use of glyphosate. Glyphosate use has increased with the planting of GE crops, and numbers of glyphosate resistant species are highest for crops for which an herbicide-tolerant GE variety exists.

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Source: Part of the International Survey of Herbicide Resistant Weeds at weedscience.org


However, not all cases of glyphosate resistance have been identified in fields where herbicide tolerant GMOs are grown. To determine if glyphosate-resistant weed species identified for crops that are not genetically engineered for herbicide tolerance arose first in fields where herbicide resistant GE crops were planted, Dr. Andrew Kniss compiled data from weedscience.org and plotted new cases of glyphosate-resistant weeds that initiated in GM-crop sites versus those that originated in non-GM crop sites.

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Source: Data from weedscience.org compiled by Dr. AndrewKniss

Remarkably, cases of glyphosate resistant weeds are no more likely to be documented in association with GM fields than non-GM fields. This is likely because glyphosate is also used in conjunction with crops that are not genetically modified for herbicide tolerance. For example, glyphosate is used to control weeds between rows in orchards and to encourage mature wheat to dessicate so it is ready to be harvested more quickly. If GMOs drastically contribute to the rise of herbicide tolerant weeds, we would expect to see a spike in herbicide tolerance corresponding with the introduction of GMOs; however, this is not the case.

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Source: Data from weedscience.org compiled by Dr. Andrew Kniss



In conclusion, herbicide-tolerance can arise from many sources. Current data do not seem to definitively point to GMOs as a significant cause for the rise in herbicide-tolerance. As Dr. Andrew Kniss puts it:

GM crops don’t select for herbicide resistant weeds; herbicides do. Herbicide resistant weed development is not a GMO problem, it is a herbicide problem.

The European Academies Science Advisory Council agrees:

Cultivating a GM crop variety with increased herbicide resistance, for example, may prove detrimental to the environment if the farmer over-uses that herbicide. But the same would be true of herbicide resistance introduced by conventional breeding.

Despite a lack of clear evidence that GMOs contribute to the rise in herbicide-resistance, many critics cite the development of “superweeds” as a reason for advocating a moratorium on GMOs. Chipotle cites as one of their reasons for removing GMOs from their menu that “GMOs engineered to…withstand powerful chemical herbicides…create herbicide resistant super-weeds.”  Chipotle’s solution to the “super-weed” problem is to switch from using oil from soybeans genetically modified for herbicide resistance, to  oil from sunflowers that are “naturally” resistant to the herbicide atrazine.  As Dan Charles of NPR points out, use of herbicides in this system has led to far more resistance problems. This graph compares numbers of species resistant to the herbicide glyphosate (ESPS Synthase Inhibitors shown in light blue) with species resistant to herbicides used on sunflowers (ALS inhibitors shown in red).

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Source: Graph from weedscience.org, comments added by Dr. Andrew Kniss

Thus, prohibiting the use of herbicide-tolerant GMOs does not eliminate problems of herbicide resistance. Furthermore, according to the USDA, planting herbicide-tolerant crops “makes it easier to manage weeds using less tillage, which can help reduce soil erosion as well as improve soil quality and water conservation”

So if banning GMOs will not prevent the development of more herbicide-resistant weeds, what will? According to the USDA:

Mitigating the evolution of herbicide resistance depends on reducing selection through diversification of weed control techniques, minimizing the spread of resistance genes and genotypes via pollen or propagule dispersal, and eliminating additions of weed seed to the soil seedbank.

The list of best management practices for managing herbicide-resistance includes “cultural practices that suppress weeds by using crop competitiveness,” following herbicide label instructions, and stacking herbicides with multiple mechanisms of action (MOA).  Dr. Stephen Weller, professor of horticulture at Purdue, compares multiple modes of action for weed control with putting more than one lock on the same door: “The thief, in this case the weed, might manage to get by one of the locks, but if you have several, as in several modes of action, it is much harder. If you can control a weed with two or three mechanisms of action, the likelihood of resistance occurring to all the mechanisms used is greatly reduced.”

The USDA has also noted that “Economic Incentives May Encourage Grower Cooperation in Managing Resistance”.

Here are a few other helpful resources on GMOs and superweeds:

Where the Superpowers of Superweeds Comes From. James Schnable, May 14, 2010

WSSA FACT SHEET: Dispelling Common Misconceptions about Superweeds

USDA APHIS Recommendations for Best Management Practices for Authorized Field Trials of Regulated Herbicide-Resistant Crops

USDA: Managing Glyphosate Resistance May Sustain Its Efficacy and Increase Long-Term Returns to Corn and Soybean Production. Jorge Fernandez-Cornejo and Craig Osteen, May 4, 2015

What does Chipotle’s switch to non-GMO ingredients mean for pesticide use? Andrew Kniss, May 18, 2015

Where are the super weeds? Andrew Kniss, May 1, 2013

What are superweeds? & Do GMOs cause superweeds? Genetic Literacy Project, Accessed April 27, 2016


The birds and the bees and the flowers? The not-so-secret sex life of plants

It’s springtime, so those of us with allergies might have noticed plants getting all animal planet with our sinuses. Seems most plants are pretty lose with their pollen, but when it comes to procreation, they’re very particular. So how do plants swipe right on a match? (For my married friends, that’s a tinder reference. For my mom, tinder is an app people use to meet people. For my dad, an app is a phone capability)

First base is geography. Plant breeders can take related plants from different regions, play some Barry Manilow, and cross them in a green house yielding new varieties. But under normal conditions, plants have to live and thrive in the same environments to cross.

Second base is timing. To our dismay allergy season is a season not a day. That’s because different plants flower at different times. They respond to environmental cues like day length and temperature and flower at the time that will yield the maximum chance of survival and success for their offspring. The timing differs depending on the plant and the method of seed dispersal/germination. So even in plants, equivalent levels of maturity are necessary for a fruitful relationship.

Third base is anatomy. For some plant species, male and female reproductive parts are found on different plants (sound familiar). I’ll spare you the analogy, but for many species, both genitalia appear on the same plant. In some cases they’re right up next to each other within the same flower. The location of plant privates determines whether plants are more likely to breed with their neighbors or themselves.

Plants are actually pretty content with pollinating themselves, and some almost exclusively self-fertilize. These loners like rice can be a real pain for breeders hoping to cross different varieties. On the other hand, corn man parts, called tassels, stick right out of the top of the plant. Wind blows the pollen from the tassels and it lands on the silky hairs that stick out of the ears of neighboring plants as much as 200 feet away

Home runs require chemistry. Assuming our gentle-pollen and lady-ovule live in the same zip code, are age-appropriate, and are serendipitously brought together (totally not by online dating), there’s still got to be chemistry. And I’m not being cute here, I’m talking about literal chemistry. In order for fertilization to occur, pollen has to produce a straw-like appendage called the pollen tube which delivers the sperm to the egg. Pollen tube growth is guided by chemicals called chemoattractants which are produced by the ovule.

Aw scent of a woman! The molecules that ovules use to lure pollen tubes had been previously identified. Just last month, two studies published in the prestigious journal Nature uncovered the male receptors that recognize their female partners. Why are these breakthroughs important? If we can figure out what prevents different species from crossing, we might be able to create inter-species mixes (like an actual “grapple” or the blue raspberries my brother keeps pushing for).

Happily ever after. So that’s what happens when two plants love each other very much. For a real R-rated experience, check out these absolutely incredible videos of plant and insect mé·nage à trois encounters.

  1. Flowers trick male wasps into thinking they are female wasps. A BBC production.

2. Flower requires bee “vibrations” to release pollen. Also a BBC production.

For scientist readers, here are the less fun but fascinating nature papers:

From Pitchforks to Personal Protective Equipment: Who is Growing Our Food?

Picture a farmer-you might conjure the popular image of Grant Wood’s “American Gothic”- a weathered old man with a pitchfork propped next to his thin-lipped apron-clad daughter. While Wood claims to have painted in appreciation of Midwestern culture, writers such as Gertrude Stein saw satire, and Iowans were outraged at their depiction as pinched, grim-faced, puritanical Bible-thumpers.”

I can’t help but wonder, if Wood were alive today, what would his Instagram look like? Would he plaster his feed with Paul Harvey quotes–God looked down on his planned paradise and said, ‘I need a caretaker.’ So God made a farmer”–or satirize his own painting, costuming his subjects in hazmat suits? Grant Wood’s depiction of a farmer may have been accurate when he painted it, but it is now a caricature. So who is really growing our food?

Farmers make up less than 1% of the US population, and a quick Google search shows that their image is complicated by labels like “organic,” “conventional,” and “GMO”. Are these images accurate? Both of the farmers themselves and of the techniques and tools they use?


These images were taken from a screen shot of the top row of results returned from a Google image search for “organic farmer”, “conventional farmer”, and “GMO farmer” respectively on April 11, 2016. These images reflect common stereotypes of different farm production systems.

When I think about farmers, I remember my friend Kyle Martinez timidly reciting Macbeth in a Shakespeare class at the University of Colorado. Despite his degree in political science, Kyle’s heartstrings pulled him back to tiny Olathe, Colorado. Now, he’s farming 200 acres, serving on the board of directors for the local energy co-op, and studying for his master’s in healthcare administration, all while working full-time for his family’s home care business. When I congratulated him on his engagement he laughed,

“it takes a strong woman to stand behind the idiots who farm”.


Kyle and Kat grow conventional and GMO corn, onions, and a variety of cover crops in Olathe, CO. Photo provided by Kyle Martinez

Kyle and Kat Martinez are first generation farmers, so they’ve had to borrow just shy of a million dollars for land, equipment, and yearly inputs just to get their crops in the ground. So far, Kyle fits Harvey’s romantic description of a farmer: “Somebody willing to get up before dawn…work all day in the fields…and stay past midnight at a meeting of the school board.” I wanted to see where he fits in the stock photo world of farmers, so I questioned his pest control methods.

We do crop rotations, and I’ve started doing cover crops in front of my sweet corn,” he tells me. “I grow a minimum-till cover crop that has 8 or 9 different crops like radishes, winter peas, turnips, winter rye grass…That’s just us trying to take better care of our soil.”

Crop rotations and cover crops are often billed as organic farming methods, so I pry, “Is any of your corn genetically modified?”

“All of what I call field corn (corn for animal feed) is Roundup Ready (RR).”

RR corn is genetically modified for resistance to glyphosate, the active ingredient in the household herbicide Roundup. So here is a farmer using not only crop rotations and cover cropping, which are often associated with organic farming, but also GMOs and glyphosate for weed control? I try searching “organic and GMO farming” and find I’ve confused Google. All of the images seem to imply the two are polar opposites firmly at odds. Yet Kyle, a conventional farmer by definition, uses the same techniques that benefit soil health in organic systems. I ask how the herbicides are applied and if he is concerned about toxicity.

“We take it upon ourselves to wear gloves and masks while we’re mixing,” he explains. “From the consumer standpoint, it’s not really a concern. With the sweet corn, the ear is not exposed and we spray the top of the onions, not the onion that’s developing underground. We do our part to make it safe for everybody else, but I’ll eat onions or an ear of sweet corn right out of the field.”

With his array of methods, Kyle doesn’t seem to fit any pigeonholed farmer images. Wondering if his hodgepodge system is unique, I interview several more farmers beginning with Doug Wilson, a classmate of Kyle’s who also lives in Olathe. Doug is also much younger than your typical farmer (averaging 58 at the last census) and has an endearing way of emphasizing the long E in “sweet corn”as he proudly gushes over his conventional crops:

“We have ‘Olathe sweet’ sweet corn, the sweetest corn in the US. The quality of our sweet corn is of the utmost importance. We do residue testing for quality assurance for our customers and we’ve never had a problem with pesticide residues.”

Doug Kylynn and Avery-27

Doug and Kylynn (with their daughter Avery) grow GMO corn, conventional sweet corn, beans, and onions on small plots in Olathe, CO. Photo provided by Doug Wilson.

Each of Doug’s fields averages 20-30 acres, not the large “industrial-type” farm we typically picture for conventional systems. I ask Doug if his family eats the crops they grow:

“We have a feedlot down the road that we sell (genetically modified field) corn to that we buy our beef from–that’s a local farmer– and we buy pork from them as well. We eat our own sweet corn, we eat our own onions, and we always keep our own beans to make chili and refried beans”

Olathe is not the only place where farmers have diversified their practices. Allen Williams, a farmer in Carro Gordo, Illinois, grows certified organic crops as well as “genetically modified soybeans for a seed company called Syngenta, and…non-GMO beans for food grain.”


Allen Williams or Carro Gordo, IL grows GMO, conventional, and certified organic crops. Photo taken and originally published by Dan Charles/NPR

Allen describes using crop rotations in his various systems as well as hand weeding and herbicides in his organic and conventional fields respectively. He explains that the yields are less in his organic systems, but the revenue per acre is double, because some people prefer to buy organic food:

“I grow varied types of crops to spread my risks. We grow organic because it’s more profitable.

John Callis, a conventional pear farmer in the Sacramento River Delta uses chemicals to control pests in his 700 acre orchard, but not the kind you might expect. The synthetic chemicals he sprays are not insecticides but moth sex hormones called pheromones. He uses an “integrated pest management (IPM) system” to “balance the good guys against the bad guys”. The moth pheromones don’t kill insects, but attract and confuse male moths, so they can’t find females during mating season. As a result, the pear-munching codling moth larvae are not produced during the part of the year when the fruit is developing. John directs me to a University of California-Davis webpage outlining similar IPM systems for dozens of crops. Many of these systems include the use of synthetic chemicals, but reflect a major goal of organic agriculture, to “optimize the health and productivity of interdependent communities of soil life, plants, animals and people”.


John, Jill, and their sons Jay & Will (from R to L) use an IPM system to grow conventional pears in the Sacramento River Delta. Photo provided by John Callis

As I reflect on my interactions with these farmers and the inaccurate representations in simplistic caricatures floating around the Internet, I consider Wood’s motivation in painting “American Gothic”. According to his biographer Darrell Garwood, Wood passed the house in the painting and “thought it a form of borrowed pretentiousness, a structural absurdity, to put a Gothic-style window in such a flimsy frame house.

The house still stands today. Perhaps Wood misunderstood the structure and the people who lived there as many of us misjudge the motivations and practices of modern farmers.  Given the rising popularity of the food movement, I hope this post inspires the reader to get to know the challenges facing real farmers rather than relying on internet stereotypes or romanticized idealizations.      


Activity: Breeding Vs. Genetic Engineering

Plant breeding and genetic engineering are incredibly useful tools. Like most tools, they serve distinct purposes. Plant breeding randomly combines the genes of two closely related plants. This is useful when both parents have several useful traits. Genetic engineering allows scientists to move specific genes between species. I used the following scenario to demonstrate the precision of genetic engineering as compared to plant breeding to freshmen at San Marin High School:


Two volunteers were selected to be “genetic engineers” and the remaining 15-20 students were “plant breeders”. Each student was given two solo cups, one representing maize (corn) and one representing its wild ancestor teosinte. Each cup contained six Popsicle sticks each representing a gene. The bottoms of the Popsicle sticks were colored green, yellow, or red. The colors represented useful genes, neutral genes (conserved between corn and teosinte), and undesirable genes respectively. Corn had three useful genes and three neutral genes. Teosinte had one useful gene (the disease-resistant trait), two neutral genes, and three undesirable genes.


Students were instructed to “make a cross” between these two species by selecting three Popsicle sticks from each cup. “Genetic engineers” had clear cups and could pick the genes they wanted. “Breeders” had red cups and had to randomly select their genes. The goal was to maximize the number of useful traits and avoid any undesirable traits.

Each of the genetic engineers selected four useful genes and two neutral genes. Breeders ended up with a variety of different combinations. Only one breeder successfully avoided picking any red Popsicle sticks; however, this student still ended up with less total positive/green traits than the genetic engineers.

The students asked what a breeder would do to generate the same optimized crop as the genetic engineers. The “breeder” whose new crop had no undesirable traits put his Popsicle sticks into a new cup and then “back-crossed” it with maize (again randomly selecting three popsicle sticks from each). After two rounds, he still had not managed to generate a variety with as many good traits as the genetic engineers. I then went on to explain that this scenario assumes there are only six genes in corn and that each of those genes acts independently. In fact there are over 30,000 genes and neighboring genes tend to be inherited together.

Creative Commons License
Hands-on Activity: Breeding Vs Genetic Engineering by Jenna E Gallegos is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.
Based on a work at https://escapingthebench.wordpress.com/2016/03/20/hands-on-activity-central-dogma-of-biology/.

Whatcha gonna do with all that junk-all that junk inside them genes?

Imagine if all the music on itunes was interrupted by blocks of white noise that you had to manually edit out every time you downloaded a song. Makes no sense right? Why would songs be recorded that way? Why not just remove the junk at the source, so you don’t have to waste time and energy?

That’s exactly what scientists wondered when they discovered genetic material known as introns. Genes are regions of DNA that are used as templates to make molecular messages called RNA. RNA provides instructions to make the proteins that determine an organism’s traits. This process, called “gene expression” is the “central dogma” of molecular biology. Before RNA is used to make proteins, large sections called introns are removed. The remaining sections, which actually contain the genetic information, are spliced back together.

Central Dogma

GENE EXPRESSION: In a process called transcription, DNA is used as a template to make an RNA message. Regions of the RNA known as “introns” are cut out, and the remaining pieces are spliced back together to yield mature RNA. The mature RNA message is then used as instructions to build a protein in a process called translation.

Introns, originally called “junk DNA“, are not present in the mature RNA and do not influence the final protein product. So why do cells waste energy, copying introns just to remove them immediately afterwards?

Returning to the music analogy, imagine itunes gives in to complaints and removes the white noise. Customers are surprised to find that suddenly some songs are not downloading as efficiently. Some can only be downloaded a few times per day, others will not download at all, and the most popular songs are hit the hardest

That’s what happens when scientists try to express genes without introns. For many genes, the intronless version does not yield as many copies of RNA. Further, some genes are completely dependent on this “intron-mediated enhancement” or “IME”. Only certain introns exhibit IME, and they tend to be found in the most fundamental genes, those that are expressed all the time.


Certain introns can increase expression of some genes to varying degrees. This figure shows three plant seedlings that all contain a gene that encodes a protein that makes a blue dye. The blue dye gene in the plant in the middle does not contain an intron. In each of the other plants, the blue dye gene contains a different intron. This work was completed by a previous student in our lab and is published in Plant Biotechnology Journal.

IME can increase the expression of genes anywhere from 2 to 20 fold in plants, animals, and fungi. In my lab, we study IME in plants, because introns are routinely used to increase expression of genes in crops from herbicide-tolerant soybeans to nutritionally enhanced rice. Better understanding IME could enable us to design synthetic introns that maximize gene expression potential.

Despite the obvious utility of IME, little is known about the mechanism. What we do know doesn’t fit conventional models of gene expression. For example, in order to exhibit IME, the intron must be very close to the start of the gene. Remarkably, if an IME intron is inserted into a gene that is usually only expressed in certain tissue, it can cause that gene to be expressed everywhere. New data shows that IME can even influence the length of an RNA message and act independent of DNA regions normally thought to be essential for expression.

If you want to dig deeper, my advisor Dr. Alan Rose and I published a review on the topic aptly titled “the enduring mystery of intron-mediated enhancement”. You can access the full-length PDF and a video summary on my publications page.

If we’re going to label GMOs, let’s do it sensibly

In my last “Let’s talk biotechpost, I discussed how challenging it is to define whether a genetically improved plant is technically a “GMO”. Determining if a given food item contains genetically modified ingredients is even more difficult.

There has been a lot of recent discussion about GMO labeling. On one side, you’ll hear that consumers have the right to know whether or not food has been genetically modified. On the other hand, many argue that labeling GMOs is unnecessary and would stigmatize a perfectly safe crop improvement technology. Missing from much of this dialogue is an explanation of what would actually be labeled.

There are only a few GMO crops currently on the market in the United States: alfalfa, canola, corn, cotton, papayas, soybeans, squash, and sugarbeets. The majority of GMO crops grown do not show up in the produce aisle directly, but are used to feed animals (alfalfa, corn, soybeans), or for oils (cotton, canola, corn, soybeans) and sugars (sugarbeets, corn) in processed foods.

So where exactly might you find a GMO label if it existed?

1.GMOs or foods containing GMOS

This is obvious. Actual whole GMO produce such as pest-resistant sweet corn, or disease-resistant squash would be labeled. Processed foods obviously containing these ingredients such as salsa with GM corn or trail mix with dried GM papayas would also be labeled.

2.Meat/Dairy from animals fed GMOs

This is a bit trickier, and still up in the air. As Ben and Jerry’s points out on their website, eating a GMO does not make YOU a GMO. For this reason, they have advertised that their ice-cream is “GMO free” for years, even though it is made from the milk of cows fed genetically modified feed. This logic seems fair enough. After all, the gene that makes alfalfa a GMO cannot be found in a pint of Cherry Garcia.

3.Processed foods made with oil/sugar extracted from GMOs

As with meat/dairy, this is a toughy. Just as the genes unique to GMOs don’t make it through a cow’s gut, they also don’t show up in high-fructose corn syrup or soybean oil. These processed ingredients are 100% identical to organic alternatives.

4.Foods produced by (or with ingredients produced by) GM microorganisms

The production pipeline of some foods and food additives relies on genetically modified fungi or bacteria. Cheese is pretty much universally made using enzymes produced by genetically modified microorganisms. Genetically modified microorganisms can also produce vitamins, which can then be used to fortify cereals. This might explain why several vitamins went missing when Grape Nuts and Cheerios went GMO-free. The GM microorganisms themselves are not present in the final product, so the only difference is a decrease in vitamin A, B12, D and Riboflavin in the GMO-free version.

So which of these foods SHOULD sport the GMO label? It’s only physically possible to differentiate those in the first category, raw GMOs or foods containing whole GMOs, from their non-GMO counterparts. Those foods in categories 2-4 are completely indistinguishable from alternatives, so it doesn’t make a whole lot of sense to label them. Nonetheless, you could argue that if you wish to avoid GMOs for religious, economic, social, or environmental reasons, you might want to know if GMOs were used in any step of the production pipeline. In that case, all foods dependent on GM technology should be labeled as such, with no exceptions. Anything in between does not make any logical sense. Unless, of course, you’re Vermont and exempting milk and cheese happens to support your own economic interests…

All of the state-specific labeling initiatives thus far (failed in California, Colorado, and Washington, passed in Vermont) have proposed a patchwork mess with illogical exceptions. Any GMO labeling law upheld in the United States should be national and consistent with no exceptions. That’s my opinion. I’d be happy to hear yours in the comments section.