Abstract

The anticipated risk of escape of transgenes from genetically modified crops to wild allies has revealed a serious lack in knowledge about gene flow from cultivated to wild forms of crop plants and its possible consequences for the environment, such as increased an increase in weeds. This proposal aims at developing molecular tools dedicated to assessing gene flow in two model crops, one basically outcrossing, chicory, and one basically selfing, lettuce. Consequences of gene flow for fitness will be studied by demographic monitoring of natural and experimental hybrid populations. Wild lettuce, L. serriola, also will serve as a model species for invasive behaviour, and its recent expansion into Northwestern Europe will be studied biogeographically with the aid of molecular markers. The results will be integrated into a model from which recommendations can be drawn for assessing GM-crop biosafety.

Objectives

• To trace evidence of introgression from cultivated to wild forms in lettuce and chicory using several molecular marker techniques comprising both neutral markers and markers linked to traits that may affect fitness, e.g. disease resistance genes.
• To establish the degree of outcrossing under field conditions in wild forms using molecular marker techniques.
• To study the consequences of gene flow from cultivated to wild forms by field trials, by demographical monitoring and by modeling both natural and experimental crop-wild hybrid populations.
• To obtain insight into the recent encroachment into NW Europe of the wild form of lettuce by characterising populations along a north-south and an east-west transect through Europe using molecular markers, paying attention to whether there is crop introgression into the wild species.
• To draw up recommendations for handling ecological aspects of assessing GM-crop biosafety.

Description of the work

The degree of outcrossing and gene flow in lettuce and chicory under field conditions is determined by following unique alleles from the hypervariable codominant molecular marker systems STMS and SAMPL through natural populations and by transplanting donor plants containing unique alleles at several distances from existing populations. The project will trace evidence of introgression from crop to wild forms, AFLP and SSAP, which both have the advantage of efficiently generating a large number of markers across the whole genome, screen natural populations. In order to ascertain a representative sampling of the genome, the project will generate genomic linkage map information, so that the introgression of specific parts of the genome can be traced. SSAP is an innovative transposable element-based PCR method. The project will trace the introgression of traits, using an innovative PCR method, called NBS-directed Profiling, which accesses the variations around disease resistance genes that are used intensively in breeding. Possible influences of introgression on fitness will be studied by determining parameters in hybrid and backcross populations which have been created under field and greenhouse conditions. The experimental hybrid populations of lettuce will be demographically monitored, to put these parameters in perspective. These will lead to matrix projection models which enable the crucial stages in the species life cycle where changes in performance will have the largest impact on population growth and fitness to be identified. In an attempt to reconstruct the recent increase of wild lettuce into north-western Europe, genetic variation will be screened on a north-south and an east-west transect through Europe, using codominant STMS. Historic and recent vegetation samples will be compared to determine whether wild lettuce is also invading new vegetation types. Project results will be integrated and disseminated to a wide audience.

Deliverables

• An estimation of the level of gene flow from crop forms to wild forms in chicory and lettuce by assessing the actual breeding system and gene flow in the field, and by tracing evidence of past introgression with several molecular-genetic marker techniques.
• An assessment of the ecological influence of introgression on the wild form by comparing fitness parameters and by demographic monitoring of experimental hybrid lines between crop and wild forms in chicory and lettuce.
• An analysis of the distribution of genetic variation of wild lettuce over Europe and a comparison of recent and past vegetation data in the light its recent invasion into Northwestern Europe.
• A model which can be used for deriving recommendations for handling ecological aspects in procedures for assessing GM-crop biosafety.
• Dissemination of the results of the project by both scientific and popular publications, and a workshop for stakeholders.

Contacts

Coordinator

• Clemens VAN DE WIEL / Plant Research International BV Business Unit Biodiversity and Identity / NETHERLANDS

Participant

• Rik van WIJK / Keygene N.V. Molecular Marker Services / NETHERLANDS
• Rikke Bagger JORGENSEN / Riso National Laboratory Plant Biology & Biogeochemistry Department / DENMARK
• Hans den NIJS / University of Amsterdam Institute for Biodiversity & Ecosystem Dynamics / NETHERLANDS
• Andrew FLAVELL / University of Dundee Division of Biochemistry / UNITED KINGDOM
• University of Udine Department of Crop Science / ITALY
• François FELBER / Université de Neuchâtel Institut de Botanique / SWITZERLAND