Coexistence and ecological biosafety of two GM crops in Europe

The three-year, EU-funded project SIGMEA combined skills from many disciplines to examine the biological, environmental, agronomic, economic and legal issues that determine whether GM and non-GM crops can feasibly be grown in the same agricultural landscape. Its conclusions differed for the two crops that have been most widely studied.

Map of field patterning in a study of cross pollination - provided by Enric Mele, SpainSIGMEA reported mainly on coexistence, but also on ecological biosafety. Coexistence refers to the need to separate, in the food production chain, different types of crop, such as those that have been developed with or without genetic modification. While zero impurity of one type of crop in another is impossible to guarantee, the EU had set a threshold of 0.9% GM content for produce that can be labelled as GM-free.

New ecological patterns from the GM crop trials (FSEs) database

Two scientific papers on food webs and species-accumulation offer new approaches to GM risk assessment and post-commercial monitoring

Image showing sites for spring-sown crops in the FSEs - beet (blue), maize (red), oilseed rape (yellow)The world's largest GM field trials - the Farm Scale Evaluations of GM herbicide-tolerant crops, the FSEs - brought more than £6M of government funding to the study of arable ecosystems. A consortium of the Centre for Ecology and Hydrology, Rothamsted Research and SCRI conducted the trials between 1999 and 2005 on more than 250 sites. The results have had wide influence on crop biotech policy in the UK and Europe. The basic comparisons of the effect of GM and non-GM cropping on biodiversity were published in around 15 papers to refereed journals including Philosophical Transactions of the Royal Society, Nature, Biology Letters, Proceedings of the Royal Society and the Journal of Applied Ecology. The trials also established an unrivalled database of arable biodiversity and field management that continues to provide a rich seam for mining and analysis.

The FSEs (the UK's GM crops trials) 1999-2005

All seedbank measurements in the FSEs were carried out by SCRI using the emergence method applied to soil sampled from the 250 or so sites used in the experiment by field staff from CEH, Rothamsted Research and SCRI.

The method was developed in 1999 on three spring and four winter oilseed rape sites. On the basis of these initial measurements, the group estimated that differences of 1.5- to 2- fold in seedbank density between treatments would be detected from around ten samples of each one litre of soil from each treatment (half field). In the event, the estimates proved correct.

From 2000 onwards, a baseline sample was taken before the treatments were applied at each of the 250 sites, and repeat samples from the same locations 12 and 24 months later. At the height of activity in 2001, thousands of trays containing soil were spread throughout several large cubicles in glasshouses equipped with temperature control and shading. In all, SCRI's seedbank records in the FSE comprise the largest arable seedbank survey in the UK.

Feral and volunteer crop populations in the arable environment

Not all the seed from crop plants is harvested; many seeds are lost, either falling to the ground within the field or dispersed by machinery, birds, etc. to end up beyond the field margins. In some cases the seeds survive in the seedbank giving rise to volunteer populations within subsequent crops or feral populations outside of the cropped area.  The persistence and spread of volunteer and feral populations can lead to significant weed problems while providing a bridge for the dispersal and escape of traits present in cultivated populations.

Volunteer oilseed rape

In the cultivation of oilseed rape (Brassica napus L.), large numbers of seed are shed and fall to the ground before and during harvest. Given the right environmental conditions a proportion of these seeds will become dormant and enter the seedbank, emerging later if subjected to appropriate germination triggers. This has led to the presence of volunteer weed populations within arable fields and to persistent seed bank populations.

The persistence and spread of novel genes

A transgenic, that is genetically modified, oilseed rape (Brassica napus) provides the model system with which we have investigated the dynamics of novel genes in local populations. A stochastic, spatially explicit individual based model (IBM) was developed to simulate the dynamics of the transgene introduced into a non-transgenic population. The model combines life-history and management processes with environmental drivers to examine the effect of these on the spread and persistence of the transgene and the conferred trait.

The model has been used to explore a number of features of this system:

Gene flow patch diagramSpread and persistence in patchy populations - Plant populations, including arable weeds, typically exhibit spatial heterogeneity, that is patchiness, in their distribution. Together with the localised nature of plant to plant interactions this has the potential to affect the dynamics of a population and the spread and persistence of the genes they posses. Model simulations have shown that small scale spatial heterogeneity in the distribution of transgenic plants combined with localised pollen dispersal reduces mixing between populations and acts to limit the spread of the gene through the population.

Agroecology News Archive

Ecological roles of weeds In an invited plenary talk, Geoff Squire represented the group's ideas on the roles of weeds at the XIII Colloque International sur la Biologie des Mauvaises Herbes held at Dijon, France 8-10 September 2009. The main points of the talk were: weeds have been with us in northern Europe for more than 5000 years - we haven't got rid of them; so we need to understand them better, spend less trying to remove them and make use of their positive roles in the ecosystem. Arable cropping in Scotland is already some way towards coexisting with weeds: its cereal yields and weed seedbanks are both among the highest in the UK!  (Added 14 September 2009)

Publications archive

Refereed publications and major reports from the Agroecology group

Newton, A.C., Begg, G.S., Swanston, J.S. 2008. Deployment of diversity for enhanced crop function. Annals of Applied Biology (doi:10.1111/j.1744-7348.2008.00303.x).

Monocultures are used in high-input systems to maximise short term profitability, but over time yield and quality can become unstable. This paper considers how diversity can be reintroduced to cropping systems to confer stability without compromising quality. It combines expertise between three of SCRI's programmes: Pathology (ACN), Genetics (JSS) and Environment (GSB).

Squire, G.R., Hawes, C., Begg, G.S., Young, M.W. 2009. Cumulative impact of GM herbicide-tolerant cropping on arable plants assessed through species-based and functional taxonomies. Environmental Science and Pollution Research 16(1), 85-94. Published online 2 December 2008 (doi: 10.1007/s11356-008-0072-6).

Co-existence with GM crops in European Agriculture

SIGMEA logoThe EU project SIGMEA is examining the feasibility of growing GM and other crops together in the agricultural landscapes of Europe. A central part of the project - Workpackage 2 or WP2 - collates and analyses experimental studies on geneflow by seed and pollen, but also considers field experiments on the ecological impacts of GM cropping. WP2 has over 20 partners who are sharing and analysing definitive data on over 100 field experiments, making the SIGMEA database the most comprehensive of its type. The agroecology group at SCRI co-ordinates this unique synthesis of biology and agronomy. Contact: Geoff Squire

Movement and Persistence of Genes in the Environment

Image of feral oilseed rape growing alongside a new field of oilseed rapeThe movements of genes and organisms over the landscape are natural processes that came to public attention in the assessment of GM crops. Issues on gene and seed movement go beyond the GM debate, and indeed, the major current research here on geneflow uses non-GM markers. The group combines statistical, molecular, genetic, mathematical and ecological skills to investigate the movement of genetic material and its consequences. It maintains large study areas in Tayside and in England in which it tracks the occurrence and persistence of volunteers, ferals and wild relatives.

Research projects

Research has developed in this topic for more than ten years through a series of projects funded from Europe, the UK and Scotland and from the research councils in collaboration with universities. Our contributions over this period include:

Ecological biosafety and gene flow

Image of Laying out field experiment in the Carse of GowrieThe agroecology group at SCRI continues to make major contributions through research and extension to questions on GM crops. We examine their potential roles in cropping systems, their positive and negative environmental effects, the movement of genetic material through pollen and seed and the  means by which GM and other crops might coexist in European agriculture. We combine knowledge of biology, modelling and molecular science to answer some of the most important topical questions in ecological biosafety. All our findings are made public. Members of the group are regularly invited to advise national and international commissions in biosafety and to develop training methods for environmental risk assessment.

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