Environmental factors cause disruptions and distortions in GM plants
Comment: This is a very important paper. We knew already that when GM varieties are bred, the best non-GM lines are used, and that the "apparent" yield increases that are flagged up by the GM corporations have little to do with the GM insert and much to do with the strength of the parent lines. We also know that yields often drop after the first few years, and that weed resistance to glyphosate (for example) rapidly develops. So does insect resistance to BT crops. This careful peer-reviewed paper shows what happens when GM varieties are moved from the greenhouse out into the field. In effect, the result is pretty chaotic -- with reduced yields, increased susceptibility to disease, increased vulnerability to environmental stress -- and an overall reduction in "fitness". There are also changes in plant morphology, and unintended and variable disruptions in the native plant genes brought about by the genetic inserts. One conclusion is that breeding for success in a particular environment (replicated in a greenhouse) does not mean that the GM plants will be capable of coping with a range of environments, predators and pathogens when they are out in the real world. That is a point made over and again by independent GM researchers but blithely ignored by regulators and governments.
What are the implications for global food security? Well, any Government Minister who thinks that GM crops are going to increase yields, feed the starving, and enhance UK and global food security is living in cloud cuckoo land. This is simply a matter of biology -- before we even start to think about social, economic, political and ethical matters.
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"Transgene x Environment Interactions in Genetically Modified Wheat"
by Simon L. Zeller, Olena Kalinina, Susanne Brunner, Beat Keller, Bernhard Schmid PLoS ONE | www.plosone.org 8 July 2010 | Volume 5 | Issue 7 | e11405
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011405
Abstract
Background: The introduction of transgenes into plants may cause unintended phenotypic effects which could have an impact on the plant itself and the environment. Little is published in the scientific literature about the interrelation of environmental factors and possible unintended effects in genetically modified (GM) plants.
Methods and Findings: We studied transgenic bread wheat Triticum aestivum lines expressing the wheat Pm3b gene against the fungus powdery mildew Blumeria graminis f.sp. tritici. Four independent offspring pairs, each consisting of a GM line and its corresponding non-GM control line, were grown under different soil nutrient conditions and with and without fungicide treatment in the glasshouse. Furthermore, we performed a field experiment with a similar design to validate our glasshouse results. The transgene increased the resistance to powdery mildew in all environments. However, GM plants reacted sensitive to fungicide spraying in the glasshouse. Without fungicide treatment, in the glasshouse GM lines had increased vegetative biomass and seed number and a twofold yield compared with control lines. In the field these results were reversed. Fertilization generally increased GM/ control differences in the glasshouse but not in the field. Two of four GM lines showed up to 56% yield reduction and a 40-fold increase of infection with ergot disease Claviceps purpurea compared with their control lines in the field experiment; one GM line was very similar to its control.
Conclusions: Our results demonstrate that, depending on the insertion event, a particular transgene can have large effects on the entire phenotype of a plant and that these effects can sometimes be reversed when plants are moved from the glasshouse to the field. However, it remains unclear which mechanisms underlie these effects and how they may affect concepts in molecular plant breeding and plant evolutionary ecology.
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Conclusions
Our study demonstrates that inserting a single transgene into the hexaploid wheat genome, along with the desired target effect such as mildew resistance in the present case, can significantly affect other phenotypic traits and thus, as in our case, change the ecological behaviour of the species (hypothesis (i) in Introduction). Such unintended effects of single genes to our knowledge are always smaller in experiments using naturally occurring genetic variation and wild plants [45], [46]. Even when we included crop plants, we could not find any publications where single genes reduced quantitative fitness traits in a plant as strongly as in the present case, yet only in the field and not in the glasshouse [47]. Commercial glyphosate-resistant soybean cultivars were found to suffer from a 5% yield depression that might be caused by the transgene or its insertion process [48]. One study tested wheat varieties with introduced resistance genes against leaf and stripe rust and reported a 12% reduction of yield [49], which was considered to be a very large effect [50]. Compared with these, the yield reductions of 48 and 56% observed in our two GM lines of wheat expressing the Pm3b transgene are much larger (Figure 3B).
We found that the level of mildew resistance as well as the magnitude of other phenotypic effects varied significantly between different GM lines (hypothesis (ii) in Introduction). We hypoth- esize that this variation in phenotypic effects may be due to different expression levels of the Pm3b transgene which in turn might have been caused by different insertion positions of the transgene in the genome. Some plant breeders suggest not selecting for plant lines with complete pathogen resistance because costs of such a resistance often outweigh benefits [47]. In our case this would speak for selecting GM lines with relatively low expression levels yet still increased mildew resistance, i.e. line Pm3b#1 [51]. However, to test the hypothetical correlation between expression level and phenotypic effects would require specific experiments with a larger number of GM lines as used here. With regard to risk assessment our findings are in agreement with the view that a each GM line should be tested in a case-by- case approach [52].
Finally, our results show that even if desired phenotypic effects of a transgene are found across a range of environments in a glasshouse experiment, some of these effects can be reversed if GM lines are exposed to natural environmental variation in the field (hypothesis (iii) in Introduction). Although it is likely that commercial plant breeders know of the presence of transgene 6 environment interactions, it seems that such observations so far have not found their way into the scientific literature. Breeding trials to select lines for further investigation do not need full replication and randomization, yet for an assessment of the ecological behaviour of such lines, replicated and randomized ecological experiments would be required. Our study may serve as an example of potential results that can be obtained in such experiments. We believe that such experiments can help us to gain a deeper understanding of single-gene effects in plant ecology and evolution.
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Expert Comment:
An Experiment in Scientific Truth: GM wheat yields 48-56% less in field experiments
Devinder Sharma
http://devinder-sharma.blogspot.com/2010/07/experiment-in-scientific-truth.html
As a student of agriculture, I had worked on a research project on genotype x phenotype interaction in some of the traditional cultivars of wheat found in the hilly State of Himachal Pradesh in northwest India, leading to my master's degree. My research project, supported by a GTZ sponsored fellowship, entailed conducting field trials on 30-odd wheat cultivars that I had painstakingly collected from different regions, for two consecutive years. I wish I had the time and the inclination to continue with the same research project for my doctorate thesis.
It was quite a laborious job. The similarly designed experiments were laid out at three different locations (from three different ecological zones) and altitude in Himachal Pradesh. The frequent travels especially to the higher reaches of Himachal Pradesh (where roads would open for not more than 6-8 months in a year) made it quite a difficult task to monitor the experiments, but at the same time posed a challenge.
Why I am telling you this is to highlight the importance of genotype x environment interactions, which receive less attention nowadays. In my opinion, the absence of multi-locational field trials under diverse environments, is what is leading to the failure of crop varieties, including transgenes, in several parts of the globe. In India, multi-location trials especially in case of genetically modified crops are being used primarily to build on seed supply. There is not enough scientific literature on genotype x environment interactions. "Breeding trials to select lines for further investigation do not need full replication randomization, yet for an assessment of the ecological behaviour of such lines, replicated and randomized ecological experiments would be required. (see the study below)"
It is after long that I have come across an excellent scientific paper that needs proper understanding and more scientific investigation. It has thrown up so many questions, and good science is all about enquiry, that the GM industry may find it difficult to fathom. And knowing its muscle- power, I am sure the GM industry will throttle the scientific community into silence. It knows how to bribe and manipulate the regulatory system (and US FDA as well as India's GEAC are classic examples) into submission, and therefore good science will remain buried.
I draw your attention to a research experiment being reported from Switzerland for transgene x environment interactions in genetically modified wheat. The team of researchers, led by Simon L Zeller from the Institute of Evolutionary Ecology and Environment Studies at the University of Zurich, had used the transgene wheat variety Bobwhite SH 98 26 transformed with a powdery mildew resistance gene Pm3b. They grew four offspring pairs, each consisting of a GM line and its corresponding non-GM line, under different soil nutrient conditions and also treated for fungicide treatments in the glasshouse as well as in the field.
What is interesting is to see the performance of the transgene in the glasshouse conditions and in the fields. It differed quite significantly. This is what the researchers found: Without fungicide treatment, in the glasshouse GM lines had increased vegetative biomass and seed number and a twofold yield compared with control lines. In the field these results were reversed. Fertilization generally increased GM/control differences in the glasshouse but not in the field. Two of four GM lines showed up to 56% yield reduction and a 40-fold increase of infection with ergot disease Claviceps purpurea compared with their control lines in the field experiment; one GM line was very similar to its control.
Interestingly, when you dwell deep, you find that in the glasshouse experiments, the researchers found that while the control lines benefited from the fungicide treatment, the GM lines reacted negatively. The next line is more significant. It says: The yield of GM lines dropped lower than the yield of the sprayed controlled lines. According to researchers, it means that the cost of resistance might be high if the pathogen is absent. I think we need more explanation for this interaction.
Unintended effects of single gene transfers, says the researchers, are always smaller in experiments using naturally occurring genetic variation and wild plants. I agree. "Even when we included crop plants, we could not find any publications where single genes reduced quantitative fitness traits in a plant as strongly as in the present case, yet only in the field and not in the glasshouse."
"Commercial glyphosate-resistant soybean cultivars were found to suffer from a 5 per cent yield depression that might be caused by the transgene or its insertion process; One study tested wheat varieties with introduced resistant genes against leaf and stripe rust and reported a 12 per cent reduction in yield, which was considered to be a very large effect. Compared with these, the yield reductions of 48 to 56 per cent in our two GM lines of wheat expressing the Pm3b gene are much larger."
The researchers also found that differences between GM plants and non-GM plants increased with nutrient levels (read fertiliser application, in the glasshouse). I am so glad that the researchers were honest in admitting that they have no explanation for this result, and have suggested more such tests across a range of environments.
Let me draw out some other salient points from this study:
1. GM plants had significantly fewer seeds and lower seed yield than control plants.
2. In the field, GM plants showed increased infestation by ergot fungus compared with control plants. In the glasshouse, soils were free of ergot fungus.
3. Like in the glasshouse, mildew infection increased with fertiliser application in the field.
4. In the field, yield of GM lines significantly differed when compared with the corresponding control lines.
5. High fungicide dose increased the extent of the stress reaction of GM plants. In the field too, environment stress reduced the fitness of the GM plants. In other words, GM plants were increasingly prone to biotic and abiotic stress.
6. GM plants differ in morphological, fitness and pathogen-related traits from their control plants.
7. The four GM lines, although with identical transgenes in homozygous condition, significantly differed among themselves. Although the researchers have given several explanations to address this mystery, including the disruption of the native genes by the insertion of the transgene, but have refrained from pointing to any definite reason.
8. There is still a question whether the over expression of the transgene led to an overabundance of its protein product and the subsequent phenotypic effects or of other mechanisms would be involved.
9. Plant morphology changed when the GM plants were exposed to field conditions, with significant differences in the flowering time, and the level of ergot infection.
10. The study concludes by saying that the lines that perform particularly well in a specific environment may perform poorly in other environments.
You can view the scientific paper at: http://www.plosone.org/article/info:doi/10.1371/journal.pone.0011405
The scientific community definitely needs to have a fresh look at GM crops in view of the disruptions that ecological and environmental factors can cause to its genetic makeup resulting in serious distortions in performance. This has grave implications for farmers, consumers and the environment. Scientists cannot be pardoned for deliberately ignoring genotype x environment interactions