title: Status of feral oilseed rape in Europe: its minor role as a GM impurity and its potential as a reservoir of transgene persistence.
abstract: OBJECTIVE
  Feral oilseed rape has become widespread in Europe on waysides and waste ground. Its potential as a source of GM impurity in oilseed rape harvests is quantified, for the first time, by a consistent analysis applied over a wide range of study areas in Europe.
  
  
  METHODS
  The maximum contribution of feral oilseed rape to impurities in harvested crops was estimated by combining data on feral abundance and crop yield from five established, demographic studies in agricultural habitats in Denmark, Germany (2), France and the UK, constituting over 1,500 ha of land and 16 site-years of observations. Persistence of feral populations over time was compared by visual and molecular methods.
  
  
  RESULTS
  Ferals had become established in all regions, forming populations 0.2 to 15 km⁻². The seed they produced was always <0.0001% of the seed on crops of oilseed rape in each region. The contribution of ferals to impurity in crops through accidental harvest of seed and through cross-pollination would be an even smaller percentage. Feral oilseed rape nevertheless showed a widespread capacity to persist in all regions and retain traits from varieties no longer grown.
  
  
  CONCLUSIONS
  Feral oilseed rape is not a relevant source of macroscopic impurity at its present density in the landscape but provides opportunity for genetic recombination, stacking of transgenes and the evolution of genotypes that under strong selection pressure could increase and re-occupy fields to constitute an economic weed burden and impurity in future crops.
authors.affiliation: SCRI, Dundee DD25DA, UK. geoff.squire@scri.ac.uk
authors.forename: Geoffrey R
authors.initials: GR
authors.lastname: Squire
authors.forename: Broder
authors.initials: B
authors.lastname: Breckling
authors.forename: Antje
authors.initials: A
authors.lastname: Dietz Pfeilstetter
authors.forename: Rikke B
authors.initials: RB
authors.lastname: Jorgensen
authors.forename: Jane
authors.initials: J
authors.lastname: Lecomte
authors.forename: Sandrine
authors.initials: S
authors.lastname: Pivard
authors.forename: Hauke
authors.initials: H
authors.lastname: Reuter
authors.forename: Mark W
authors.initials: MW
authors.lastname: Young
mesh_terms: D029688:Brassica napus / Q000235:genetics* / Q000502:physiology; D004784:Environmental Monitoring; D005060:Europe; D030821:Plants, Genetically Modified / Q000235:genetics*; D054817:Pollination; D011156:Population Density; D011157:Population Dynamics; D019076:Transgenes