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Genetically modified organisms (GMOs):
The significance of gene flow through pollen transfer

European Environment Agency (EEA) Environmental issue report No 28 Mar02

A review and interpretation of published literature and recent/current research from the ESF ‘Assessing the Impact of GM Plants’ (AIGM) programme for the European Science Foundation and the European Environment Agency

Authors: Katie Eastham and Jeremy Sweet, with contributions from other participants in the AIGM programme

Project manager: David Gee European Environment Agency Genetically modified organisms (GMOs): The significance of gene flow through pollen transfer

Experts‘ corner

Correspondence regarding this report should be addressed to:
Dr J. B. Sweet, NIAB, Huntingdom Road, Cambridge, CB3 0LE, UK
e-mail: jeremy.sweet@niab.com

European Environment Agency
Kongens Nytorv 6
DK-1050 Copenhagen K
Denmark
Tel: (45) 33 36 71 00
Fax: (45) 33 36 71 99
E-mail: eea@eea.eu.int
http://www.eea.eu.int

Executive summary

In 2000 the EEA established a special project for the European Parliament, on the dissemination of research results from technologies characterised by scientific complexity and uncertainty, such as GMOs and chemicals, and on the use of such results by the public and their representatives in their governance, including the use of the precautionary principle. This project is in support of the EEA duty, added to its regulation in 1999, to ‘assist the Commission in the diffusion of information on the results of relevant environmental research’. In order to access European scientific expertise and to minimise duplication, the EEA established a partnership with the European Science Foundation to bring together relevant scientific evidence. This is the first report from the project. Other reports will summarise monitoring programmes and exposure data for some representative chemicals, and the use of consensus conferences and other methods for involving the public in complex scientific issues. The project will support the EEA in its work of helping to develop appropriate monitoring and data sources on the impacts of complex economic/ environment interactions.

The European Science Foundation (ESF) had already established a research programme, ‘Assessing the Impact of GM Plants’ in 1999. This AIGM programme brings together researchers and other scientists from 10 European countries involved in assessing the environmental and agronomic impact of GM crops, including studies of gene flow and dispersal through pollen, hybridisation and gene introgression. The AIGM programme was invited by the ESF to produce a review of pollen mediated transgene flow based on recent research by participants in the AIGM programme as well as from published reports and papers. (The AIGM programme is briefly described in the appendix).

This report considers the significance of pollen-mediated gene flow from six major crop types that have been genetically modified and are close to commercial release in the European Union. Oilseed rape, sugar beet, potatoes, maize, wheat and barley are reviewed in detail using recent and current research findings to assess their potential environmental and agronomic impacts. There is also a short review on the current status of GM fruit crops in Europe. Each crop type considered has its own distinctive characteristics of pollen production, dispersal and potential outcrossing, giving varying levels of gene flow.

Oilseed rape can be described as a high-risk crop for crop-to-crop gene flow and from crop to wild relatives. At the farm scale low levels of gene flow will occur at long distances and thus complete genetic isolation will be difficult to maintain. This particularly applies to varieties and lines containing male sterile components, which will outcross with neighbouring fully fertile GM oilseed rape at higher frequencies and at greater distances than traditional varieties. Gene stacking in B. napus has been observed in crops and it is predicted that plants carrying multiple resistance genes will become common post-GM release and consequently GM volunteers may require different herbicide management. Oilseed rape is crosscompatible with a number of wild relatives and thus the likelihood of gene flow to these species is high.

Sugar beet can be described as medium to high risk for gene flow from crop to crop and from crop to wild relatives. Pollen from sugar beet has been recorded at distances of more than 1 km at relatively high frequencies. Cross-pollination in root crops is not usually considered an issue since the crop is harvested before flowering. However a small proportion of plants in a crop will bolt and transgene movement between crops may occur in this way. Hybridisation and introgression between cultivated beet and wild sea beet has been shown to occur.

Potatoes can be described as a low risk crop for gene flow from crop to crop and from crop to wild relatives. Cross-pollination between production crops is not usually considered an issue since the harvested tuber is not affected by incoming pollen. In true seed production areas, however, the likelihood of cross-pollination between adjacent crops leading to contamination is higher. The risk of gene flow exists if volunteers are allowed to persist in a field from one crop to the next. Naturally occurring hybridisation and introgression between potato and its related wild species in Europe is unlikely.

Maize can be described as a medium to high-risk crop for gene flow from crop to crop. Evidence suggests that GM maize plants would cross-pollinate non-GM maize plants up to and beyond their recommended isolation distance of 200 m. There are no known wild relatives in Europe with which maize can hybridise.

Wheat can be described as a low risk crop for gene flow from crop to crop and from crop to wild relatives. Cross-pollination under field conditions normally involves less than 2 % of all florets so any outcrossing usually occurs with adjacent plants. Hybrids formed between wheat and several wild barley and grass species generally appear to be restricted to the first generation with little evidence for subsequent introgression due to sterility.

Barley can be described as a low risk crop for gene flow from crop to crop and from crop to wild relatives. Barley reproduces almost entirely by self-fertilisation, producing small amounts of pollen so that most outcrossing occurs between closely adjacent plants. There are no records of naturally occurring hybrids between barley and any wild relatives in Europe.

Some fruit crops, such as strawberry, apple, grapevine and plum have outcrossing and hybridisation tendencies which suggest that gene flow from GM crops to other crops and to wild relatives is likely to occur. For raspberry, blackberry and blackcurrant the likelihood of gene flow is less easy to predict, partly due to lack of available information.

At present none of these crops has pollen which can be completely contained. This means that the movement of seed and pollen will have to be measured and managed much more in the future. Management systems such as spatial and temporal isolation can be used to minimise direct gene flow between crops, and to minimise seed bank and volunteer populations. The use of isolation zones, crop barrier rows and other vegetation barriers between pollen source and recipient crops can reduce pollen dispersal, although changing weather and environmental conditions mean that some long distance pollen dispersal will occur. Biological containment measures are being developed that require research in order to determine whether plant reproduction can be controlled to inhibit gene flow through pollen and/or seed.

The possible implications of hybridisation and introgression between crops and wild plant species are so far unclear because it is difficult to predict how the genetically engineered genes will be expressed in a related wild species. The fitness of wild plant species containing introgressed genes from a GM crop will depend on many factors involving both the genes introgressed and the recipient ecosystem. While it is important to determine frequencies of hybridisation between crops and wild relatives, it is more important to determine whether genes will be introgressed into wild populations and establish at levels which will have a significant ecological impact.

Project summary

A. Results:

Different crop species have different rates of autogamy (self pollination) and outcrossing. In addition some crops have hybridising wild relatives while others do not. The characteristics of the main crop types crops are summarised as follows:

Crop                                       Frequency of gene flow from outcrossing
                                           Crop to crop          To wild relatives
Oilseed rape                               High                  High 
Sugar beet                                 Medium to high        Medium to high 
Maize                                      Medium to high        No known Wild Relatives 
Potatoes                                   Low                   Low 
Wheat                                      Low                   Low 
Barley                                     Low                   Low 
Fruits - 
strawberry, apples, grapevines and plums   Medium to high        Medium to high 
Raspberries, blackberries, blackcurrant    Medium to high        Medium to high 

Source: EEA/Sweet

B. Implications:

The environmental and agronomic impact of gene flow depends on the specific trait/ plant combination and the likelihood that gene transfer will occur. (Risk = Hazard/ impact x frequency). For example: Environmental fitness genes in frequently outcrossing species present the highest risk; environmentally neutral genes in inbreeding species present the lowest risk.

C. Recommendations:

Gene transfer through cross pollination can be limited by effective biological and physical barriers. More research is needed to examine the options for these in the light of recommendations from the EU on thresholds for contamination of non-GM crops.

Transgene introgression into wild species is often associated with hybridising ability. However research has shown that there are physiological barriers operating that inhibit adoption of genes in wild species or populations. Research is needed on actual levels of gene transfer into wild populations from crops and factors involved in genes being adopted by wild populations.

Both temporal as well as spatial gene flow also arises through seed persistence and dispersal. More information is needed on the role of seed banks and dispersed seed of GM crops on contamination of subsequent crops.

Better management systems and stewardship schemes to minimise GM contamination and gene flow require good scientific information on both seed and pollen mediated gene flow.

Future monitoring of experimental and commercial releases of GM crops must be based on good scientific knowledge of the behaviour and ecology of the GM crop and its wild relatives. Understanding gene flow and introgression is a key part of this requirement.

Introduction

1.1. Aims and objectives of the report

This report considers the significance of pollen mediated gene flow from six major crop species commonly grown in Europe that have been genetically modified and are close to commercial release in the European Union (EU). Existing data including the most recent research on oilseed rape (Brassica napus ssp. oleifera), sugar beet (Beta vulgaris ssp. vulgaris), potatoes (Solanum tuberosum), maize (Zea mays), wheat (Triticum aestivum) and barley (Hordeum vulgare) has been compiled under individual crop sections to form a review and interpretation of the potential environmental and agronomic impacts of each crop. With this we aim to advise on appropriate measures to restrict gene flow or minimise the impact of transgenes moving from crop to crop and from crop to wild plant species. Each crop is reviewed with particular reference to the following points:

i) reproductive biology and crop use;
ii) genetic modification;
iii) pollen dispersal;
iv) gene flow: Crop to crop;
    • hybridisation and gene flow;
    • possible consequences of gene flow;
v) definition and status as a weed plant;
vi) gene flow: Crop to wild relative;
    • compatibility and distribution;
    • hybridisation and gene flow;
    • possible consequences of gene flow;
vii) conclusion.

Information on current GM research involving the main fruit crops grown in Europe will also be given in the form of short reviews. Grapevine (Vitis vinifera), plum (Prunus domestica L.), apple (Mallus x domestica), strawberry (Fragaria x ananassa), blackcurrant (Ribes nigrum), raspberry (Rubus idaeus) and blackberry (Rubus fruticosus) will be focused on to give evaluations of the risk and possible effects of pollen-mediated gene flow from these crops.

To conclude the report, future recommendations and considerations are discussed with regard to crop to crop and crop to wild relative gene flow, along with methods of minimising gene flow, such as developing physical and biological barriers.

1.2. Background

Genetic modification can potentially improve crop quality and productivity. The molecular techniques employed to do this essentially involve the insertion and integration of a short segment of DNA from a wide variety of novel genes from unrelated plants, microbes and animals into the genome of a plant. Genetic modification has the advantage of allowing the addition of a single character to breeding lines and varieties without the need for backcrossing to remove unwanted genetic linkages (DoE, 1994). Genetically modified (GM) crops were first released commercially in 1992. Their global area covered 11.0 million hectares in 1997 and had increased by 16.8 million hectares to 27.8 million hectares in 1998. Estimates in 2000 suggest that approximately 50 million hectares of GM crops are now grown. The five main GM crops grown in 1999 were, in order of the largest area, soybean (Glycine max), maize, cotton (Gossypium hirsutum), oilseed rape and potato, with herbicide tolerance and insect resistance the most utilised genetic traits.

In 1998 the first commercialised GM crop was grown in the European Union (EU). Estimates suggest that introductory quantities of insect resistant maize were grown primarily in Spain (20 000 hectares) and France (2 000 hectares). Other crops being developed for commercial application in the EU include sugar beet, oilseed rape (herbicide tolerance) and potatoes (modified starch) (Dale, 1999). There is no commercial growing of GM crops in several European countries including the UK. However certain imported products have been approved for food use: slow ripening tomatoes, soya that is resistant to a broad-spectrum herbicide (glyphosate), insect-resistant maize (Halford, unpublished), and herbicide tolerant rapeseed for oil.

Despite the potential benefits of GM crops, there is also concern over the possible environmental and agronomic impacts if the transgenes ‘escape’ and become established in natural or agricultural ecosystems. From an agronomic point of view, the transfer of novel genes from one crop to another could have a number of implications, including depletions in the quality of conventional and organic crop seed leading to a change in their performance and marketability. Maize, for example, will cross-pollinate with other cultivated maize and sweetcorn (Zea mays ssp. saccharata), directly affecting the quality and acceptability of the marketed product. Concerns over the ecological impacts of GM crops lie with whether or not a crop has wild relatives and the ability to cross-pollinate them. If crops hybridise with wild relatives and gene introgression occurs wild populations could incorporate transgenes that change their behaviour and they could present an economic threat as weeds or an environmental threat as competitors in natural communities. Oilseed rape, grasses and several fruit crops have varying degrees of sexual compatibility with a number of wild relatives found in Europe, and introgression of novel crop genes into some of these relatives is likely. Other crops, for example maize, have no wild relatives with which they could potentially cross-pollinate in Europe.

1.3. Factors affecting pollen dispersal and cross-pollination

1.3.1. Size of pollen source and sink

The extent of cross-pollination between fields of crops or between crops and wild plant populations is largely dependent on the scale of pollen emission and dispersal (Raybould & Gray, 1993). Klein et al (submitted) used models to estimate the dispersal patterns of maize pollen in various spatial designs. The cross-pollination rate from one field to another was shown to depend on the sizes of both fields. If pollen disperses from a small source area it may behave as a narrow and unpredictable diffusion cloud. Evidence indicates that most airborne pollen from small to moderate sized fields contributes to the local component in this way (Treu & Emberlin, 2000). A theoretical study by Crawford et al (1999) examined the effect of increasing pollen source size on resulting levels of cross-pollination. He concluded that a square 400 m2 crop would emit 3/4 the amount of pollen that a 4 ha (40 000 m2) crop would emit, but suggested that the effectiveness of pollen dispersal would decline significantly in crop areas of less than 400 m2. Due to conclusions of this kind many believe that small-scale field trials have done little to remove uncertainty over the scale of pollen emission and dispersal likely to emanate from genetically modified crops. Throughout this study we place greater emphasis on field trials carried out on an agricultural scale when drawing conclusions for potential cross-pollination.

1.3.2. Pollination vectors

As well as being dispersed on the air current and by wind, pollen can be effectively distributed by insects. Pollen produced by some crops, for example oilseed rape, can be dispersed over considerable distances by both wind and insects. The weather can affect the behaviour of pollinating insects on the crop and the occurrence of airborne pollen movement so the amount of crosspollination can vary significantly from crop to crop and day to day. The numbers and even species of natural pollinating insects can vary considerably in their contribution to successful pollination (Faegri et al, 1992). The bumblebee (Bombus sp.) is an example of a pollinator which moves only short distances between flowers so the majority of pollen is deposited in the immediate surroundings of the pollen source. By contrast, the foraging habits of the pollen beetle (Meligethes aeneus) mean that they emigrate from a crop in large numbers and often fly over long distances (Skogsmyr, 1994).

1.3.3. Environmental factors

Pollen released on the airflow can settle by gravity, can be removed by precipitation, be absorbed into water droplets, or can impact onto surfaces including vegetation, buildings, soil and water bodies. The relative importance of these sinks and the impacts they might have will vary with factors such as the terminal velocities of the pollen grains, climate, local vegetation and topography (Treu & Emberlin, 2000).

1.3.3.1. Weather

Pollen dispersal can be heavily influenced by the weather and changes in temperature, humidity and light, as well as wind and rain. For example, studies on pollen dispersal by Scott (1970) over several years revealed that the average concentration of oilseed rape pollen during one day of one year measured 1.4 % of that on the same day the following year. This was due to heavy rain and high humidity on the first day compared with sunshine and low humidity on that day a year later. Wind strength can also have an important role in distributing pollen grains significant distances within their viability periods.

1.3.3.2. Local environment

Patterns of pollen dispersal can be heavily influenced by variable factors in the immediate local environment such as the nature of the plant canopy, surrounding vegetation and topography. Wind velocity and airflow are affected by topography, potentially influencing pollen movement from a pollen source to receptor plants.

1.3.3.3. Physical barriers

Woods and hedges can serve as barriers to air flow, having dual effects of depleting some pollen from the air flow by impaction and filtering and also creating a sheltered zone in the lee. Dense stands of shrubs, herb covers and tree-sized vegetation with full foliage act as catchments for airborne particulates, including pollen (Treu & Emberlin, 2000). Jones & Brooks (1952) conducted experiments with tree barriers adjacent to a crop of maize. The results indicated that a single row of trees with underbush were effective in reducing the amount of outcrossing by 50 % in the plants situated immediately behind the barrier, but was much less effective at greater distances from the barrier. The authors concluded that the tree barrier was less effective in reducing outcrossing than an area of barrier crop occupying an area of equal size to the trees.

The effects of barrier crops and isolation zones on pollen movement are discussed in Section 10.4.

1.3.4. Pollen viability and competitive ability

Biological factors influencing successful pollination begin with the ability of the donor plant to produce viable pollen, and the length of time the pollen grain retains its potential for pollination. If the competitive ability of the pollen grain is poor its capacity to compete with fresher pollen produced in the vicinity of the receptor plant will be poor. Pollen viability can vary greatly between species but is also dependent on environmental variables such as temperature and humidity (Treu & Emberlin, 2000).

1.3.5. Levels of outbreeding in the crop

The amount of outbreeding in the crop is an important aspect to consider. Govidaraju (1988) demonstrated a significant positive correlation between outcrossing rates (largely determined by pollination mode) and gene flow variables, reflected in the different isolation requirements for various crops. Wheat, for example, is typically selfpollinated, with cross-pollination under field conditions usually involving less than 2 % of all florets (Wiese, 1991). Oilseed rape is known to be mainly self-fertilising and/or insect pollinated although pollen can become airborne and travel several kilometres downwind. Floral morphology and pollen characteristics are also important as the morphology and terminal velocity of pollen grains influence dispersal patterns.

1.3.6. Degree of synchrony in flowering times

There must be some overlap in flowering times between the pollen donor and the receptor plant so that ripe pollen and receptive stigmas are produced at the same time, in which case a higher degree of crosspollination might occur than if partial selfpollination had begun in one of the plants.

1.4. Hybridisation, gene flow and introgression

In its broad sense ‘hybridisation’ can be defined as the cross-breeding of genetically dissimilar individuals. Such individuals may differ by one or a few genes (the pure lines of plant geneticists), by several genes (e.g. hybrid maize) or be very different genetically (as in most hybridisations between members of different genera). Hybridisation is common within species but can also occur between species and occasionally with species in different genera. Hybridisation between different species can be described as ‘interspecific’ hybridisation or, where species belong to a different genus, ‘intergeneric’ hybridisation (DoE, 1994). The incidence of natural interspecific and intergeneric hybridisation varies substantially among plant genera and families.

Hybridisation is a frequent and important component of plant evolution and speciation, although the resulting F1 plants are often sterile and relatively few populations persist, except where the parents remain in contact or where they are able to spread vegetatively (Raybould & Gray, 1993). Table 1 (overleaf) demonstrates the many factors that determine the production and establishment of viable hybrids. The frequent occurrence of fertile hybrids increases the chances of introgression, the incorporation of alleles from one taxon to another, mediated through repeated backcrossing of hybrid individuals to one of the parents.

Gene flow can be defined as ‘the incorporation of genes into the gene pool of one population from one or more populations’ (Futuyma, 1998). Such gene movement is a major determinant of genetic structure in natural populations. Gene flow is strongly influenced by the biology of the species and is likely to vary with different breeding systems, life histories and modes of pollination. Assuming sexual compatibility between a crop and wild relative, the entry and subsequent spread of a transgene into natural populations will be determined to some extent by pollen movement. Different crop species have different pollination mechanisms (insect and wind) and different seed dispersal patterns. Both may act as vectors for transgenes from crops, but the subsequent dispersal of the genes through pollen and seeds may be completely different (DoE, 1995), depending on the reproductive characteristics of the species.


Table 1 Factors determining the likelihood of hybrids, between crop plants and related species, becoming established in agricultural or natural habitats.

The production of viable hybrid seeds
1. Compatibility of the two parental genomes (mitotic and genetic stability)
2. Ability of the endosperm to support hybrid embryo development
3. Direction of the cross: one parent may support embryo and seed development better than the other
4. Number and viability of hybrid seeds

Establishment of hybrid plants from seeds in soil
5. Seed dormancy
6. Vigour of the hybrid plant
7. Direction of cross: maternal effects influencing seedling vigour
8. Nature of habitat: wild, semi-wild or agricultural
9. Nature of competition from other plants
10. Influence of pest, disease and animal predators

Ability of the hybrid to propagate vegetatively and sexually
11. Method of vegetative propagation
12. Persistence of vegetative propagules in agricultural habitats
13. Dissemination of vegetative propagules
14. Invasiveness of vegetative propagules in natural habitats
15. Sexual breeding system: cross-compatible, self-compatible, ability to cross to either parental species
16. Male and female fertility: meiotic stability and chromosome pairing
17. Seed number and viability
18. Seed dormancy
19. Nature of habitat: wild, semi-wild or agricultural
20. Nature of competition from other plants
21. Influence of pest, disease and animal predators Source: Dale (1994)


Gene flow is measured in various ways. The most common direct method for plants is the observation of seed and pollen movement, which gives an estimate of potential gene flow (dispersal). Other methods use genetic markers to estimate actual gene flow. A simple method is to introduce or identify plant in a population with a unique genetic marker (e.g. an isozyme allele) and to follow the appearance of the marker in the next generation (e.g. Latta et al, 1998). Transgenes can act as convenient markers for tracking gene flow and the results of various studies of this kind are discussed in later chapters.

Throughout the report both the potential for gene flow between crops, and from crops to wild relatives will be discussed. The frequency and occurrence of genetic movement between different plants forms the basis of practical decisions about the isolation requirements of crops where varietal purity of the seed is essential. Some crops have sexually compatible relatives that are found as wild plants and arable weeds. Sugar beet, for example, can be accompanied by related wild beet, and there is well-documented evidence of gene transfer between the two (Boudry et al, 1993).

1.5. Routes of transgene movement between species

A transgene can be regarded as having ‘escaped’ from the crop if:

(1a)The plant containing it persists after the crop, possibly becoming a weed of agricultural, especially arable, land.

(1b)The plant containing it persists in the disturbed habitats associated with agriculture or other human activities (e.g. headlands, roadsides, waste tips).

(1c)The plant containing it invades seminatural habitats (e.g. saltmarshes, sand dunes, heathland, and woodland). or

(2a)The transgene is transferred by pollination to another crop which persists in agricultural habitats.

(2b)As (2a), but the plant occupying disturbed habitats.

(2c)As (2a), but the plant invading seminatural habitats. or

(3a)The transgene is transferred by pollination to a wild related plant which (possibly by introgression) persists in agricultural habitats.

(3b)As (3a), but the plant occupying disturbed habitats.

(3c)As (3a), but the plant invading seminatural habitats. (DoE, 1994)

The first route involves either vegetative persistence or transmission of the genetic modification in seed from generation to generation. Plants produced by (1b) or (1c) are referred to as feral plants throughout the report. With exception to the cross-pollination event in route 2, this route is akin to route 1 and may range from the movement of a transgene from a GM crop to a non-GM crop of the same variety, to movement between crop varieties and between related crop species. The modes of escape described in route 3 refer to the movement of transgenes from crops to wild species or native populations. Hybridisation with wild relatives may cause problems in a number of ways: by genetic erosion (particularly in centres of diversity); through genetic pollution of natural gene pools (Gray & Raybould, 1998), and by weeds conferring a selective advantage, such as pest and disease resistance, leading to a change to the persistence or invasiveness of a species (Dale & Irwin, 1995). Ultimately the consequences of hybridisation between crop and wild species will depend on the nature of the transgene and the fertility of the hybrid and any of its progeny (McPartlan & Dale, 1994).

Though the emphasis of this report is on pollen mediated gene flow, it is important to recognise that this comprises of only one element of the movement of genes within and between populations. Seeds may be distributed in time through their dormancy mechanisms as well as in space. The importance of the latter was highlighted recently when an import of conventional rapeseed from Canada to Europe was found to contain traces of adventitious GM material which has not been approved for planting in Europe (Coghlan, 2000). Although detailing gene flow through seed dispersal is beyond the scope of this report it will be highlighted where, together with cross pollination, it is considered to play a significant part in the movement of transgenes.

Download complete paper (300kb PDF file) from The Campaign to Label Genetically Engineered Foods at http://www.thecampaign.org/EEAPollenReport.pdf


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In order to provide possible inputs to the developing work programme of the EEA, and to stimulate debate on issues that may contribute to the identification, framing and evaluation of environmental policy measures, the EEA, from time to time, asks independent experts to summarise their views on topical or upcoming issues, so that the EEA can consider publishing them as Experts’ corner reports.

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Appendix: Assessment of the Impacts of Genetically Modified Plants (AIGM)

The European Science Foundation (ESF) is the European association of research funding agencies, national research organisations and national academies of sciences and letters from 24 European countries. Its role is to stimulate, develop and support research at a European level, principally in the basic part of the research spectrum. It does this through networking researchers from across Europe and, through its Scientific Programme Scheme, receives additional financial contributions from its Member Organisations on an à la carte basis. The AIGM programme was started in 1999 and the level of interest in the topic of the impact of genetically modified plants may be seen from the large number of agencies supporting the programme. ESF warmly welcomed the opportunity to work with the European Environment Agency on this important topic, building on the expertise available through the AIGM programme and thus producing an additional European added value.

Genetically modified (GM) plants are approaching commercialisation and widespread deployment in Europe. Risk assessments supporting release applications have largely been based on assumptions that genetic modifications of plants will not alter their behaviour, or that of other organisms, in the natural environment. These assumptions are made from limited information on actual levels of gene flow occurring between crops and wild species and small scale experiments with GM plants and untransformed plants. Large scale releases of GM plants occurring in North America and other countries provide some additional information on risks but are not always relevant to European environments. There is thus concern that risk assessments are based on limited experimental data which do not fully take account of the novelty of the transgenes or the scale and scope of their ultimate commercial deployment. There is also concern at the large number of different releases that are being proposed in Europe. Information on the transgene interactions within and between GM plants is extremely limited, as is information on the environmental impacts of multiple transformations in single plants, many of which could arise unintentionally. An additional concern is that GM plants may require different agronomic management or may have agricultural consequences that impact on the environment, e.g. changes in agrochemical usage, effects on predators etc. Agricultural impacts are not always considered in environmental risk assessments, and yet agriculture is a significant component of the total European environment.

A workshop in Cambridge, UK, in October 1997, sponsored by the European Science Foundation, brought together European scientists involved in environmental impact research, plant breeders and representatives of organisations involved in the regulation of GM plant releases. They discussed the range of transformations and plant species most likely to have environmental impacts. They agreed on a number of research priorities and also agreed that research in Europe required coordinating and enhancing so that scientific information could be collated and conclusions made more widely available to support risk assessments in European countries and elsewhere.

The AIGM Programme has been established to coordinate the activities of the principal research programmes in Europe, to enhance them by recruiting younger research personnel to study in them, and to encourage these research programmes to respond to the new research priorities identified by the Programme. It publicises the results of the research through conferences and workshops to a wide range of audiences in Europe particularly to countries with little experience with GM plants and risk assessments. Members of this Programme are available to give expert views on risk assessments and to assist with the development of regulations based on sound scientific principles.

The Programme lasts for 5 years, from 1999 to 2003. It is supported by the following ESF Member Organisations:

The Programme Steering Committee has the following membership:

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