Plants
EC research puts impact
of GM plants to the test

Introduction

M. Tepfer,
Laboratoire de Biologie Cellulaire,
INRA-Versailles (FR)

The EC began funding biosafety studies of genetically modified plants (GMPs) in 1989, shortly after the first field tests in Europe. EC support has continued since then with different degrees of intensity and continuity, suggesting that the considerable ongoing progress in GMP biosafety research was based on a relay between national and EC funding.

The 18 projects described in this chapter deal with biosafety questions relevant to GMPs from a plant biology point of view. In other chapters, in particular those focusing on food safety, plant growth-promoting micro-organisms, biocontrol micro-organisms, or "tools", many or most, in fact, of the projects are plant oriented. The projects in this chapter are thus only part of a remarkable, much wider-ranging EC effort to assess the potential impact of the field release of genetically modified organisms that are important to crop plants.
Top

If we look at the research areas covered in this 11-year period, some clear trends emerge. During the first half of the period, research was focused on a single rather narrow area devoted to determining if GMPs themselves were invasive, and if gene flow could be expected to occur from GMPs, either to related plant species, or to associated microbes. Although plant gene flow studies were not then supported by the EC, considerable progress was made, presumably with national sources of funding. Currently, in spite of considerable effort, there is still no actual evidence for gene flow between kingdoms, either plant-to-bacterium (BIOT-CT91-0282) or plant-to-fungus (BIOT-CT91-0287). In contrast, plant-to-plant gene flow in outcrossing wind-pollinated crops has been clearly demonstrated, including crosses with related species in the case of genetically modified oilseed rape. During the current programme, gene flow studies are supported again, but in addition to determining if gene flow can occur from plant species other than those previously studied, such as wheat or foxtail millet (IC18-CT98-0391), there is a new focus on the potential ecological impact of transmission of particular types of transgenes (conferring resistance to nematodes, ICA4-2000-30019, to a herbicide, IC18-CT98-0391, or to a virus, QLK3-2000-00361) from a crop species where gene flow is known to be possible, as is the case for oilseed rape, sugar beet or wheat in Europe.
Top

During recent programmes, studies have focused on certain types of transgenes, in particular those conferring resistance to insects or to viruses, with a clear tendency to study systems of increasingly complex biology. For instance, in the insect resistance project (BIO4-CT96-0365), research was focused on potential effects of beneficial non-target insects that feed directly on plants, such as bees. It was extremely important to show that these insects, in fact, were not affected by the GMPs on which they were fed. In contrast, the more recent project (QLK3-2000-00547) proposes to study effects on tritrophic interactions, involving a plant, a herbivore, and a predator or parasitoid of the herbivore, in order to determine if there are negative effects on predators and parasitoids. Although no direct effect on the latter insect types is expected, the insect-resistant GMPs are expected to reduce the population size of their prey (the desired effect on herbivores). This in turn may well have an indirect effect on the third trophic level, and thus more generally on the structure of insect biota. A similar progression is observed in the projects on virus-resistant plants. The projects (BIO4-CT96-0773 and BIO4-CT98-0374) focused primarily on identifying potential sources of risk, whereas the more recent project (QLK3-2000-00361) proposes to assume that the risk exists, and to focus on its potential impact, in comparison with the situation in non-transgenic plants. There is, in fact, a pronounced general tendency to compare the effects of GMPs to those of systems based on non-GMPs.
Top

Once a potential risk has been identified, research can be devoted to diminishing or eliminating its impact, which is a key part of risk management. This can be exemplified by one of the projects on virus-resistant GMPs (BIO4-CT96-0773). This project focused primarily on the phenomenon of heterologous encapsidation in transgenic plants expressing a viral coat protein gene, which could have an impact on the epidemiology of viral diseases via changes in the interactions with virus vectors, such as insects, nematodes or fungi. The researchers showed that it was possible to modify the transgene to eliminate the interaction with the vector, while maintaining its ability to confer virus resistance, in essence eliminating a source of potential risk. In a similar problem-solving mode, a newly-launched project (QLK3-2000-00060) proposes to develop a system for the selection of transformed cells that would not be based on antibiotic resistance. Although no risks have been scientifically associated with the antibiotic resistance genes commonly used to generate transgenic plants, the new system would avoid this highly polemical problem, and could thus contribute to improving public acceptance of GMPs.
Top

As we have seen above, GMP biosafety research is often closely tied to solving problems due to potential risks associated with specific transgenes. Even these studies however have provided considerable information of fundamental interest. For instance, as mentioned above, GMP biosafety research has led to considerable advance in our understanding of gene flow and pollen dispersal. Previously, this area drew its conclusions primarily from plant breeders' relatively modest requirements for seed purity, and information on the exact extent of potential gene flow was lacking. It is also reassuring to note that fundamental research that in the long term will only have an impact on GMP biosafety has also been supported, with funding of particularly large consortia devoted to research on transgene silencing (BIO4-CT96-0253) or on homologous recombination (BIO4-CT97-2028) in plants. Although these projects were not funded as biosafety research per se, it is most appropriate that they be presented here, since solid risk assessment must clearly be based on thorough understanding of the fundamental mechanisms underlying gene transfer and transgene function.
Top

What can we see as new emerging research needs? It is encouraging to note that two currently funded projects (ICA4-2000-30019 and IC18-CT98-0391) include studies involving developing countries. However, it is clear that such biosafety research efforts will have to be expanded in order to meet these countries' specific needs. The vast majority of GMPs belong to just a few crop species, and in most cases the new traits are encoded by a single gene whose product has little or no effect on the plant's biochemistry. As more complex traits that profoundly modify plant biochemistry are introduced into crops, such as ones that modify the characteristics of important plant products (oils, carbohydrates, etc.), or those that confer resistance to abiotic stresses (salinity, cold, drought, etc.), much more complex ecological questions will be raised which will of course require further, and more sophisticated biosafety evaluation. We are also currrently lacking essential information on the farm-scale performance of GMPs. For instance, many of the first GMPs could, in principle, lead to reduction in pesticide use, or to use of less toxic ones, or increase yield, or reduce costs. But will they in fact keep their promise? Only carefully conceived and executed farm-scale research will give us the answers. Beyond this, at some stage, the results of risk assessment of GMPs must be integrated into a broader perspective that will make it possible to weigh the advantages and disadvantages of various solutions for improving agriculture, with or without the various types of GMPs under consideration.