Last updated on May 6th, 2015 at 01:32 pm
Scientific American blared a headline that “Genetically Modified Crops Pass Benefits to Weeds,” which claimed that the results of a study of GMO rice indicated that the rice might pass certain genetic information to “weeds,” which will then get an unintended biological fitness increase. They stated that the GMO rice could pass bioengineered genes from the GMO rice to the weeds.
The underlying peer-reviewed article, trumpeted by Scientific American, may not say what they think it says. In fact, in my review (below), I’m not sure it was very well done.
The paper
It’s time to look at the actual underlying paper, instead of a journalist’s interpretation of what was written, which is often clouded by their own biases. The Scientific American story is based on an article published in a very respectable journal of plant sciences, called New Phytologist. The article was written by Wang et al., and they concluded the following:
- They determined that physiological traits and field performance of rice crop/rice weed hybrids had a fitness (increased ability to produce a next generation) because of the over-expression EPSPS gene, which was developed to confer glyphosate (Monsanto’s Roundup) resistance in rice. The reason to place this EPSPS gene into rice is to allow it to be resistant to glyphosate, so that farmers can control non-rice crop weeds (including wild forms of rice which have no agricultural benefit).
- They found that transgenic crop–weed hybrids produced 48–125% more seeds per plant than nontransgenic controls in monoculture- and mixed-planting designs without glyphosate application.
- They also determined that transgenic plants also had greater EPSPS protein levels, tryptophan concentrations, photosynthetic rates, and per cent seed germination compared with nontransgenic controls.
If there results are accurate, it would be case of gene transfer from the target plant (crop rice) to the weed plant (non-crop rice or grains) would give the weeds a theoretical advantage over the crops. In other words, the farmer could use all of the Roundup they wanted, and the weeds would be the ones that survived. This would be a case where GMO crops could lower yield.
Except, maybe not.
In a review of the Wang et al. paper, one researcher was less than impressed. And I’m not impressed either. Here are a few points that matter in judging the quality of this study:
- Primary research. It’s a primary paper, which means it’s the first to make this claim about GMO rice transferring a fitness advantage. In fact, it appears to be the first article to discuss this type of advantage for any crop. As I’ve stated before, it is best to avoid primary sources (ones in which the authors directly participated in the research or documented their personal experiences) but instead, utilize secondary sources (which summarizes one or more primary or secondary sources, usually to provide an overview of the current understanding of a medical topic, to make recommendations, or to combine the results of several studies). The reason secondary sources are so valuable is that they combine the works of several authors (and presumably locations), eliminating biases of one laboratory or one study. This doesn’t mean this study, just because it is a primary one, is worthless, but it lacks confirmation from other laboratories.
- Repetition of experiments. In my review of the article*, along with other reviews, it was established that there was no repeat of any of the experiments by the original researcher. They did the research at one location, under one set of conditions, with one type of soil. Would this observation be the same in Alabama? Or Japan? Or anywhere? Most journals that publish articles on environmental effects want longer time periods, results from experiments done over a large number of areas, and significant repetition of the data under different variables. I’m surprised that New Phytologist, a moderately high impact journal, would have such weak requirements for repeatability, but I would speculate that the journal wanted a big news story article. They got one.
- Inconclusive results. Though the authors make the claim of increased fitness of the transgenic weed plants (which of course has been broadly disseminated), the results were less than satisfying. It appears that the weed/rice hybrid arose from a different strain of GM rice, but the authors chose to compare the hybrid to a strain that is not associated with the hybrid. So, they’re making a claim of increased fitness when the measurements of fitness appear to be cherry-picked out of data that actually shows that there isn’t a fitness increase. In fact, the fitness level of most of the GM + weedy rice hybrids was below that of non-GM rice. Three out of four of the groups of hybrid rices showed no change in fitness!
- Development of weed-rice hybrids. Here’s the biggest problem. Weedy rice may have some inherent fitness advantages because of genetic diversity. And because the second and third generations of the weedy hybrids self-pollinated, it’s possible they derived the minor fitness advantage that they exhibited not from the EPSPS glyphosate resistance gene, but because of some other, unknown or poorly understood, genetic advantage in the weedy rice that has nothing to do with the transgenic gene. In other words, without properly controlling all of the millions of genetic combinations that could confer an advantage to the hybrid, we don’t know if the transgene had anything to do with it. This would be like forcing humans with blue eyes to keep cross breeding, then concluding that humans with blue eyes are smarter. Maybe it was hair color that made them smarter. Or larger brain volume. Or anything.
- Controlling for genes close to the EPSPS gene. The authors determined that hybrids that had EPSPS gene were glyphosate resistant, and those that didn’t, weren’t. That makes sense, but for the fact that genes sometimes are closely linked to other genes. In other words, there may have been a half dozen other genes linked to the EPSPS that conferred an advantage to the hybrid. The authors “assumed” that it didn’t. But that’s not even a reasonable assumption, that’s again ignoring other possibilities to confirm your hypothesis. Again, why was this article published?
Even though I don’t think that this study showed what everyone is claiming it showed, there’s another issue. In fact, if this really works, it gives a way to create a better GM hybrid rice that increases yield, substantially. All we have to do is determine what genes, that help express higher fitness, are linked to the EPSPS gene, patent it, sell this new hybrid seed, and we’re good to go. We have a higher yielding rice crop. And maybe we could find a similar gene combination in other grains.
So why is the article such a big deal?
It is well accepted observation that when the pseudoscience or anti-science crowd runs out of supporting evidence (usually when it’s thoroughly debunked by scientific skeptics), it has to rely upon a whole range of logical fallacies, errors in reasoning to support a position in an argument or debate. Because scientific skeptics (or if we’re talking about medicine, science based medicine) always demand high quality evidence to support claims, the anti-science and pseudoscience pushing troupes are frequently cherry picking “peer-reviewed” research to use as their “proof” for their claims.
Worse yet, because they are afflicted by confirmation bias, always looking for evidence to support their beliefs rather than seeing what the evidence supports, these pseudoscience types ignore the vast majority of evidence or tend to misinterpret the evidence. So, when you read some blog post or pseudo-news article about a published scientific article that says GMO’s are dangerous, you need to dig beyond the headlines, and head right to the scientific source to determine what is really being said. And that happened this week.
So, here we go. The experiments were fairly poorly designed (again what was the journal thinking when they accepted the study). And the results, even if true, may not lead to where the anti-GMO forces think it leads. It may just lead to better, more productive, GMO rice!
TL;DR version
- Glyphosate resistant GMO rice may pass its genes to weed rice.
- This research has not been repeated anywhere.
- The weedy rice may gain some fitness advantage.
- The weedy rice/GMO rice hybrid may actually be useful for developing future strains of rice.
- Even if the above were all shown to be accurate, it does not provide any evidence of any issue with GMO rice, given the hundreds of other scientific articles that support GMO crops.
* The original article is hidden behind a paywall. I cannot stand paywalls for scientific and medical articles, because too many people read only the abstract, and try to conclude that they understand it, just from a few words. Good critical thinking skills requires us to read the whole article.
Editor’s note: This article was originally published in August 2013. It has been completely revised and updated to include more comprehensive information, to improve readability and to add current research.
Key citations:
- Wang W, Xia H, Yang X, Xu T, Si HJ, Cai XX, Wang F, Su J, Snow AA, Lu BR. A novel 5-enolpyruvoylshikimate-3-phosphate (EPSP) synthase transgene for glyphosate resistance stimulates growth and fecundity in weedy rice (Oryza sativa) without herbicide. New Phytol. 2013 Aug 1. doi: 10.1111/nph.12428. [Epub ahead of print] PubMed PMID: 23905647. Impact factor: 6.736.
