Gene flow, IP, and the terminator

“Terminator seed” has been back in the news and blogs, due to some rumors that the Convention on Biological Diversity would consider rescinding the ban on the technology. Before I get knee deep into the politics, I’d like to make some quick comments on gene flow. First, pollen of many types of plants are capable of traveling quite far. The exact distances are dependent on wind, weather, plant density, species, etc. For the most part, though, pollen stays near its origin, so that gene flow between separated populations is slow (not many fertilizations between populations). It is fairly easy to test gene flow and pollen spread rates.
An elegant example was prepared by Jason Haegle, an undergraduate at Iowa State under distinguished professor Peter Peterson. As described in The Flow of Maize Pollen in a Designed Field Plot, Jason planted purple corn surrounded by yellow corn. He planted the rows 0.76 meters apart (much wider than normal) to eliminate any effect of plant density. He simply counted the purple kernels on the ears in the yellow corn fields to determine how much and how far the pollen spread. Yellow corn plants that were closest to the purple corn of course had the most purple kernels. Three rows into the yellow corn, numbers of purple kernels (thus amounts of pollen from those plants) dropped dramatically. Other studies on maize pollen flow agree that the majority of pollen stays near the plot. As Jason says in his paper, this is likely because maize pollen is large and heavy compared to pollen from other grasses.

If the goal is to avoid pollen spread and thus gene flow from cultivated to wild varieties or from one cultivated variety to another, there are several precautions that a farmer can take. First, planting of barrier rows around the variety one wishes to contain will “soak up” most of the pollen. Second, the farmer can choose plants that are early or late flowering, so that pollen shed will not coincide with the fertile period of nearby plants. Third, plants with a low level of outcrossing (natural selfer) could be chosen. Fourth, mechanical means such as removing the pollen producing parts of the plant can be used. These options apply to all crops, not just maize. Feel free to let me know if there are more options that I’ve haven’t mentioned here! Now, even with these precautions, it is possible for a few pollen grains to stray.
If you are very concerned with pollen spread, the pollen could be made sterile through natural or technological methods. The natural method would be to use a male sterile line. Despite the rather obvious evolutionary disadvantage, plant breeders have been able to maintain this trait. The technological method is of course terminator genes. There are a few very different reasons why plants like this would be beneficial: making hybrid seed, protection of intellectual property, containment of transgenic traits, and protecting the environment from pollen spread.
Phillip McClean of ND State has a clear explanation of how the male sterile trait is used in seed production. In order to make hybrid seed in maize, the tassel (pollen producing part) must be removed from the female parent or “she” will just fertilize herself (each corn plant has both male and female parts). Some people realized that they could just use male sterile lines to make the hybrids, eliminating the need for de-tasseling. Hybrids are far superior to their parents due to heterosis (hybrid vigor). Seed for maize, rice, soy, and more are often sold as hybrids because they produce better yields and have other advantageous characteristics.
The seed provides a benefit to the farmer, but does not breed true. If the farmer saves and replants the seed, the resulting plants will be completely different from the parents. In other words, farmers who plant hybrid seed either have to buy it every year or invest in the large amounts of time, space, and money that it takes to do it on their own. Alternatively, the farmer can plant non-hybrid or open pollinated varieties. I’ll follow up with a post on the pros and cons of hybrid and specialized seed so this post can stay on topic.
Seed companies can afford to develop new lines and new hybrids because they sell seed year after year (note that the seed industry is starting to provide poor farmers with superior seed at little or no cost such that licensing doesn’t affect those who most need the seed). With genetically engineered seed, the trait of interest can be passed to other plants, so the farmer could save seed and retain the trait (either purposefully or accidentally), without paying for it. Saving seed that is protected under intellectual property law is a crime without the proper licensing agreements (similar to how music is protected). For an in depth discussion on why transgenic traits (and some non-biotech crops as well) are considered IP, please see ISU Bioethics Professor Clark Wolf’s discussion of the origins of plant IP. The idea that any unit of life, even a gene, could be patented is strange and seems inherently unethical. However, the way capitalism works is that it rewards innovators. Without monetary reward, there is no impetus to innovate (consider the problem of not enough research into malaria medicine while there are multiple drugs for erectile dysfunction). If we don’t want to depend on corporations for development, much more public and private money must be spent (such as with the Gates Foundation funding malaria research and the Chinese government funding research into improved rice varieties). The investment of seed development (transgenic or traditional) is high, and has a unique problem not faced by any other industry – the product can reproduce itself!
Ideally, patents would be on certain applications, not on the genes or plants themselves, but this is a legislation problem that has nothing to do with science. Terminator seed is one example of a proposed way to solve the intellectual property problem that incidentally has a few other benefits. Terminator seed is widely misunderstood. The name makes it sound far scarier than it is. Seriously, there are no seeds shooting guns at bystander seeds, killing all in their path. The technology is actually called “Genetic Use Restriction Technology” or GURT. The particular system in question is just one of many that can result in sterile seeds. The benefits include protecting a seed company’s’ intellectual property rights and preventing biotech crops from growing where they are unwanted (read: so as to eliminate outcrossing with native plants or organic crops).
There is one op-ed in particular that I’ve seen tossed around the web. It appeared in The Guardian on 22 May, written by Sol Oyuela of Progressio (a Catholic charity that claims to focus on poverty but has been less than progressive, despite the name). Sol states in his Blogger profile that he has a Master’s degree, but doesn’t feel the need to tell us what the degree is in. Of course, I have quite a few problems with his statements.

As the world grapples with the impact of global food shortages (Six million Ethiopian children at risk of malnutrition, May 21), the livelihoods of 1.4 billion of the world’s poorest farmers who rely on harvesting seeds from one crop for sowing the next season is under threat from biotech companies which are pushing to commercialise “terminator” technology – genetic engineering that results in plants producing sterile seeds. The advent of these so-called suicide seeds represent an insidious attempt to privatise plant life – and force poor families in developing countries to buy new seeds each year from the large companies that control the $19bn global seed market.
A global ban on terminator technology struck eight years ago is now under threat from a powerful alliance of biotech companies and countries with vested interests. They argue terminator technology should be considered on a case-by-case basis, thereby undermining the blanket moratorium. We fear the ban will once again come under pressure at this week’s UN summit on the convention on biological diversity in Bonn.
Biotech companies’ claims that terminator technology will prevent contamination between GM and non-GM crops are hotly contested, yet the EU and, by implication, British taxpayers are contributing to the development of the technology through a £3.4m EU research project investigating ways that seeds can be brought back to life with chemicals. In the developing world, small-scale farming is how millions of families survive. It is vital that at the Bonn summit this month the UK government strongly supports the continuing global ban on terminator technology.

First, terminator seed does not change the ability of farmers to sow seed they grew themselves. It is important to remember that hybrid seed already must be purchased every year. Farmers are still welcome to save seed that isn’t protected or to develop new varieties on their own. Poor farmers may be able to receive improved seed at reduced cost, as I stated before. In other words, the terminator trait doesn’t actually change anything. On the Progression site, Sol expands on the ideas in his letter, telling us that:

If commercialised, Terminator would put an end to the practice of seed-saving, which is essential to 1.4 billion of the world’s poorest farmers who save and re-plant seeds from one year to the next to feed their families and earn a living. What makes Terminator different from other genetically modified seeds is the fact that it would:

  • Force farmers to buy new seed from large companies that control a global seed market worth US$19.6 billion.
  • Further jeopardise the food security of the world’s poorest communities that are already struggling to cope with rising food prices.
  • Reduce biodiversity by forcing farmers to abandon local seed varieties in favour of commercial seeds.
  • Make farmers more vulnerable to climate change by forcing them to use commercial seed rather than locally adapted varieties, which are far more resilient to unpredictable weather patterns.

There could very well be factors that I’m not aware of, but as of this moment, I think these statements are a complete lie. We can’t have a healthy debate about lies, and are reduced to a nuh-uh battle that helps no one, least of all the 1.4 billion poor farmers or the 6 million starving Ethiopian children Sol speaks of. Seriously, guy, please step into reality and then we can talk about it. If terminator seeds are available on the market tomorrow, how does that change what farmer does with the seeds in his hand today? The addition of terminator seeds to the market won’t change the choices farmers have of what seeds to buy or not buy, has nothing to do with food prices, and doesn’t force the farmers to abandon seeds they already have.
Plant life is already privatized to some degree in that patents on either genes, plants, use of plants are considered valid by many countries. As I stated before, this is necessary to a point, or we would have no improved crops at all due to the huge cost of development (biotech or not) unless we were willing to spend a lot more tax money on agriculture. Some people beleive that we would be better off without improved crops – but the increases in yield alone that can be achieved through hybrids can not be denied (even without the addition of fertilizer). If the ban on GURTs was lifted to allow a case-by-case approval (as if anything is getting approved in Europe anyway), the genes would not suddenly appear in every seed on the planet. It would be used judiciously by the seed companies for certain specialty crops. It wouldn’t be used in all new seed for the simple reason that it’s more expensive, as it takes time and money to breed the genes into a given line and it takes chemicals to “awaken” the seed.
Even though Sol and other opponents of GURTs seeds might not come out and say it, the real reason (in my opinion) that they oppose the technology is that it might open the door to production of industrial compounds and other products in crops. These types of genetically engineered crops can not be used with out some very strong safety devices, and some version of GURT might provide that safety (in conjunction with other methods of containment). The actual report given to the Convention on Biological Diversity (why not just call it Convention on Biodiversity?) by EcoNexus and the Federation of German Scientists is a bit more lucid than that of Progressio. It’s long but interesting, although I don’t think it’s right for the CBD to only consider a report written by an openly anti-biotech and anti-corporate organization. I mean, a little peer review and unbiased science would be nice. So would a few less uses of “e.g.” in the text.
Anyway, regardless of its faults, the report has a point: the big problem with terminator technology (as created by Delta and Land) is that the pollen is still fertile. So, even if other pollen containment strategies are used, some pollen will get out, making unwanted fertilizations. The resulting seed would be sterile, so it doesn’t matter, but theoretically a large amount of the pollen could fertilize a nearby field, possibly ruining a farmer’s chances to save seed (and possibly contaminating the crop with a non-edible protein). It could also theoretically fertilize wild relatives of the crop, possibly decreasing biodiversity by shrinking the gene pool. I wholeheartedly agree with the authors on this point. However, the problem wouldn’t continue beyond this point because the genes will effectively delete themselves from the population – unless there was a mutation in one or more of the involved genes.
The other problems with this particular GURT, as described in the report, have to do with mutations, silencing, and segregation. It is true that mutation or silencing could disable one or more of the genes, but we do have to remember that this would happen at a very low frequency, and would likely be noticed before the new version of the gene was passed to many other plants. I imagine that the crops containing the GURT would be rotated with a different crop so that it would be easy to see and remove volunteers. It is possible that the transgene and the three genes in this GURT version could segregate away from each other if a diverse population of plants were open pollinated. However, I doubt that the plants would be a diverse population – instead I’d imagine that the company selling the GURT protected seed would be selling inbred or hybrid plants that are homozygous for the necessary genes.
Surely, if they were to go to the trouble of using the technology, they’d ensure that it was as stable as possible. There is also at least one way to avoid the problem of segregation and to increase the stability of all involved genes: the mini-chromosome. Just in case anyone from Monsanto or Syngenta is listening, I think the best course would be to scrap this version of terminator, and look for something much closer to male sterility. It just makes more sense. Occam’s Razor, don’t cha know. Oh, and if this type of GURT is to be pursued, please try to find some more creative activators and repressors besides antibiotics and steroids.

Written by Anastasia Bodnar

Anastasia Bodnar is a science communicator and science policy expert with a PhD in plant genetics and sustainable agriculture from Iowa State University. Anastasia has had various risk analysis roles in US government and military service. She serves as BFI's Director of Policy and as Co-Executive Editor of the Biofortified Blog.


  1. The problem with a male sterile line is that maize still needs to be fertilized to set seed. That’s why cytoplasmic male sterile lines used in hybrid seed production have to be crossed with lined containing a restorer gene so the hybrid will produce viable seed.

    I’d imagine the same issue would be encountered with a transgenic male sterility line, at least until we figure out how to create lines of maize that are facultatively parthenocarpic, producing seed even with the ear is unfertilized. I know the seed companies have looked at that off and on, but so far with no real success.

  2. I really liked the explanation of CMS in hybrid production by Phillip McClean. If a sterility/restorer combo that wasn’t present in natural or cultivated populations could be designed and multiple copies of the sterility gene were included in the final crop (because the odds of more than one becoming mutated are small), then it should be a lot less leaky than the Delta and Land terminator version. Does sterile pollen physically interfere with fertile pollen? If not, then this would solve every problem listed by EcoNexxus.

    Parthenocarpy makes a lot of sense for crops that we don’t want or need seeds from, but I’m not surprised that seed companies are having a hard time getting seeds that don’t require fertilization. Do you have any references on that, by chance? It’s a very cool thought, and would work nicely for biorefining and pharma crops.

  3. My understanding of CMS is that the plants don’t successfully form pollen grains, so with would be little or no sterile pollen produced it shouldn’t compete with fertile pollen. But I could be misremembering entirely.

    The parthenocarpy in maize comes from a single talk I attended three years ago, so I assume not much has come of it yet. The successful work I’ve read of comes from eggplant (link at bottom of post), not a major agronomic crop, but it demonstrates the ability to engineer parthenocarpy into a species that previously lacked the trait. If it’s every accomplished in maize (much harder in maize since the yield is the seed itself, not that fruit… on second thought there may be a separate word for this rather than parthenocarpic, but it’s escaping me), the female inbred line could carry both the parthenocarpy and CMS genes. In the presence of pollen the plant would fertilize normally, but in pollens absence (a whole field of male sterile plants) the plants would still set seed and there would be no fertile pollen to drift into neighboring fields.

    Eggplant link:
    Nature Biotechnology 15, 1398 – 1401 (1997) doi:10.1038/nbt1297-1398;jsessionid=FD553D3224C0D9AF0C50BC211DCAEC21

  4. You do know that it was the use of a single CMS gene that caused, via a pleiotropic effect, the Southern Corn Blight disaster of the 1970s?

    I wholeheartedly agree that opponents of GMOs ought to embrace GURTs with open arms, and have“ rel=”nofollow”>said so many times.

    Of course, as we all know, this isn’t now, and never has been, about rationality.

  5. Jeremy,

    I don’t think it would be difficult to either find (or make?) a CMS gene that doesn’t have pleiotropic effects or to develop germplasm through breeding that isn’t affected.

    It’s obvious from their fervor that GMO opponents completely do not understand GURTs – but so baffling to me that they wouldn’t do some research, at least so they can ‘know the enemy’. We all have google, after all.


    Can we use the word parthenogenesis? It sounds crazy since we are talking about plants, but I think it is applicable.

    I’ve heard about work on gametophillic incompatibility (not gametophobic) but am finding nothing about it in journals or on the web. Any thoughts?

  6. In a hybrid using male strile line as a female , and a resotrant male, the pollens in f1 are fertile and they can cross to a larger distance to a sextualy compatible plant. In f2 of such hybrid the segragation to female is nearly 100% . So all the plants comming out of f2 seeds are sterile so no prapogation of the generation . as well it will cross to your nearbye farmar killing his seeds by cross pollination in f1. This is the main reason why we are loosing all the native seeds after introduction of such hybrids. Even the restorant male of sterile female which are used to get such hybrid can not be prepaired without genetic engg. still all the seed gaits are using such terminator added seeds under the banner of reserch hybrids . It’s nothing but the cheating.

  7. Ram, I’d like you to clarify your comment, please. I can’t see any reason why this pollen would “cross to a larger distance to a sextualy compatible plant”. I also don’t know why you say “In f2 of such hybrid the segragation to female is nearly 100%” because the F2 seed wouldn’t be planted (being no longer hybrid thus no longer carrying all of the desired traits consistently).

    The goal of the GURT system is to contain a gene, so that it can not spread into the environment (which both prevents unwanted gene flow and protect intellectual property). The whole point is to avoid making the next generation of seed, so I don’t see how this is a downfall of the system.

    You worry that “it will cross to your nearbye farmar killing his seeds by cross pollination in f1” which isn’t accurate. The seeds won’t be “killed”, they will be sterile.The odds of every single native seed or every single farmer’s seed being pollinated from a nearby field are tiny. In fact, as I describe in the beginning of the post, pollen generally stays near its source, and there are temporal and mechanical means to prevent pollen spread. Also as I describe in this post, even if a farmer’s field or a wild population of plants has some fertilizations with GURT pollen, the “terminator” gene removes itself from the gene pool very quickly (as the seeds are sterile). Finally, no farmer could have lost seed after the introduction of GURT protected plants because none have ever been planted!

    I hope that you will reread my post and think about the subject a little further. I am by no means saying that GURTs should be widely used. I am saying that there are problems with the Delta and Land version of GURT, but that doesn’t invalidate the entire idea.

  8. […] I covered some physical and genetic ways to prevent this in a post at Genetic Maize called Gene flow, IP, and the terminator, but we all know that 100% exclusion of unwanted pollen is impossible (at least for […]

  9. <I>The idea that any unit of life, even a gene, could be patented is strange and seems inherently unethical. However, the way capitalism works is that it rewards innovators.</I>

    Not seems unethical: <I>is</I> unethical. Capitalism rewards capitalists, and the relentless extension of "IP" is one of the principle means by which wealth and power are concentrated.

    The big problem with GMOs, and terminator seeds in particular, is that they place more and more power in the hands of a few big companies. It is naive, at best, to say they do not affect the small farmers who save their own seed. Big agrotech companies can afford to take a local loss while they drive out competition, just as supermarkets drive out small shops.

    <I>If we don’t want to depend on corporations for development, much more public and private money must be spent (such as with the Gates Foundation funding malaria research and the Chinese government funding research into improved rice varieties).</I>

    That is exactly what should be done – public money in particular. Until it is, you are working to increase the concentration of wealth and power, and against the interests of small farmers. whether you intend to or not.

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