V-GURTs (Terminator Technology)

Design, Reality and Inherent Risks

January 2006
17 pages
V-GURTs: Design, reality and inherent risks448.35 KB



The report can also be found as the official Information Document UNEP/CBD/WG8J/4/INF/17 on the CBD website at http://www.biodiv.org/doc/meetings/tk/wg8j-04/information/wg8j-04-inf-17...

1. Overview

This paper describes in brief the concepts and design behind Terminator technology or Genetic Use Restriction Technology (GURTs) in language accessible to non-scientists. It details the different elements that are theoretically required to assemble gene sequences designed to prevent the germination of seeds.

Having described in brief the way in which the technology is intended to work, the paper then discusses the reality of the technology having to function as part of a biological system, this being the plant, its molecular components and the broader ecosystem, which is inherently changeable and unpredictable. In becoming part of the biological system and its evolutionary processes, the mechanism of GURTs, along with its molecular components, will itself become inherently changeable and unpredictable.

With reference to GURTs, the paper outlines some of the many known problems that can occur in biological systems and details some specific factors that can go wrong with such a complex molecular design and mechanism.

The paper points out that the technology stands in direct conflict with two key defining characteristics of a living organism - its ability to reproduce and its ability to adapt. This latter point, combined with the evolutionary tool of natural selection pressure, raises questions as to whether GURTs can perform reliably or indeed what the consequences would be, were it to fail.

Looking at both scenarios, i.e. for the technology to succeed or to fail, some outcomes can be foreseen, but it must be emphasised that many are unpredictable. However, the potential impacts on agriculture are serious. Reduced levels of germination, unpredictable variability in crop performance, and contamination of crops with GM traits, could ultimately result in food insecurity. This paper concludes that GURTs cannot be used as a predictable or reliable technology. Rather it concludes that the technology of inducible seed sterility is likely to introduce a series of new and, unpredictable problems, with negative implications for biodiversity, agriculture, food security and sustainable livelihoods.

2. Brief description of terminator technology (V-GURTs)

Terminator technology, technically known as a Genetic Use Restriction Technology (GURTs), is designed to render seeds sterile at harvest. To this end, plants are genetically engineered with specially designed sequences of genes, that allow for external control over the activation of particular traits (e.g. herbicide tolerance, production of insecticidal compounds, fruit ripening, seed fertility). Such traits can be switched on or off through the application of inducers, such as particular chemicals. In the case of terminator technology, the chemical treatment of seeds prior to their sale to farmers is designed to trigger a genetic process that will allow the plant to grow and to form seeds, but will cause the embryo of each of those seeds to produce a cell toxin that will prevent its germination if replanted after harvest. As this affects the reproduction and viability of a whole crop variety it is technically referred to as varietal-genetic use restriction technology (V-GURTs).


6. Final Conclusion and Discussion

To date, no functional and complete V-GURTs application has been detailed in the scientific literature. The evaluation presented in this paper of the V-GURTs design, its reliability and performance has therefore relied on details contained in relevant patent documentations and on evaluation of its envisaged components as reported in the scientific literature.
Terminator technology, technically known as a Genetic Use Restriction Technology (GURTs), is a complex design of genetic engineering and molecular interaction. It is composed of three expression systems, two of which are inducible, and one chemical that will function as an inducer to trigger the terminator mechanism. For V-GURTs to perform as designed, the following must be realized:

Firstly: All three expression systems must work to the right level of protein production (repressor, recombinase and cell toxin) at the right time in the right cell system; respond to sufficiently and reliably to the external as well as to the internal inducer; not respond to unspecific induction; and not become active unless induced.

Secondly: All three expression systems and their genes must stay linked and remain stable and unchanged over generations of seed multiplication.

As detailed in this paper, neither of these above requirements is being met. Events, or problems, that have been observed in either transgenic plants or in genetic engineering experiments with components of V-GURTs include: gene Silencing and epigenetic changes of DNA; mutations; loss of promoter activity; leaking promoter systems; insufficient induction of promoter systems by inducing agents; unspecific or unintended induction of promoter systems; segregation of the different genetic components during reproduction. Additionally, toxicity and impact of inducers and repressors on the plant, environment and human and animal health will also require consideration.

A system can only be as good as its weakest parts. At present, none of the components tested for any of the possible V-GURTs systems are 100% reliable or effective. Given that, the individual components of V-GURTs offer less than 100% efficiency or reliability, the combination of these components in one organism will amount to still less. For example, if each of the 4 components (including the inducer) performs to 95%, in combination their performance could reduce efficiency or reliability to as little as 81%.

Equally, future evolution of a V-GURTsscenarios and potential consequences detailed in section 5 illustrate that both seed sterility and inheritable contamination with terminator transgenes and additional trait transgenes could have serious implications for biodiversity, agriculture, food security and sustainable livelihoods. The indications point to V-GURTs exerting further strain and unpredictability on already vulnerable agriculture systems and communities.

A serious drawback of V-GURTs is that farmers growing conventional or traditional crops of the same species as the V-GURTs variety in neighbouring fields will find their crops contaminated via cross pollination. This may severely impact food security while also being a problem for marketing and for food safety, especially if the GM crops in question were pharmaceutical crops or others not intended for human consumption. Farmers who save their traditional or conventional seeds for replanting may find a significant percentage do not germinate and would consequently experience important yield loss.

Theoretically seed sterility cannot spread, since once the trait is activated the seed will not be able to grow and no reproduction will be possible. As shown through the scenarios developed here however, there is potential for the trait of seed sterility to spread to cultivated or wild relatives – albeit in a non-activated or silenced form. If at a later stage, segregation of the V-GURTs genes takes place, gene silencing is being reversed, or promoter leakage or unspecific induction occurs, the trait of seed sterility would be activated. The impact of later generations of plants becoming sterile could potentially be severe, depending on the degree of contamination and spread of the “silent” terminator mechanism.

An issue so far sidelined and not yet understood, is the impact of the genetic modification process (transformation) on the integrity of the plant and its genome (Wilson et al. 2004). V-GURTs involve the insertion of at least 3 gene constructs, more if there are other GM traits for other purposes that are incorporated. The products of each of these have the potential to cause unintended alterations to the plant’s biochemistry (Schubert 2002). This is also a potential consequence of any unintended mutations created during their insertion (Wilson et al. 2004). Risks would consequently increase if the transgenes were not all placed on one plasmid and inserted in one single transformation. These additional risks, combined with the uncertainties, mean that V-GURTs may create many new biosafety risks, with potentially serious impacts for Indigenous and local communities and smallholder farmers.

7. Regarding the Convention on Biological Diversity

In accordance with the precautionary principle, and reflecting that there is no indication that the scientific problems of GURTs could be resolved, we urge Parties to the Working Group on Article 8(j) to support the conclusions of the “Ad Hoc Technical Expert Group report on the potential impacts of genetic use restriction technologies on smallholder farmers, indigenous and local communities” and its recommendations that COP reaffirm paragraph 23 of its decision V/5 III on GURTs and that Parties and Other Governments consider the development of regulatory frameworks not to approve GURTs for field-testing and commercial use.