Do genetically modified strawberries pose a threat to wild varieties? Do genetically modified strawberries pose a threat to wild varieties? Strawberries are an important niche product in Switzerland. Breeders are experimenting with genetic engineering methods to enhance the marketability of this product. There are risks inherent in this approach since the transfer of modified genes to wild strawberries could endanger the continued existence of the wild varieties. Background Transgenic varieties of strawberry with higher yields and enhanced root development already exist. The first release trials have already begun in Italy. However, if transgenic varieties of strawberry cross-breed with wild ones, there may be negative effects. The hybrids produced in this way are often sterile, yet by back-crossing with wild types or by producing prolific numbers of offshoots they can penetrate the native flora and displace it. Objectives This project has two basic goals. First, it seeks to assess the extent to which transgenic strawberries are capable of cross-breeding with their wild relatives. Second, it seeks to investigate the possible ecological impact of such crossbreeding under various environmental conditions in order to assess the risks associated with cultivating transgenic strawberries in the open. Methods Greenhouse experiments with honey bees, the most important pollinators of strawberries, will be carried out to show whether and how efficiently natural pollination occurs between transgenic and wild strawberries. Genetic methods will be used to determine how frequently foreign pollination between cultivated and wild strawberries has already occurred in the open in the past. The possible ecological implications of this will be quantified using life history data such as growth and competitive pressure. In these experiments, transgenic and artificially cross-bred strawberries from the laboratory will be planted in various soils. Significance The cultivation of transgenic plants is associated with potential risks for their wild relatives. Scientists have warned that the latter could become extinct as a result of undesirable cross-breeding. However, to date the true extent of these risks has barely been investigated. This project aims to close this gap by generating basic data with transgenic and wild strawberries as model organisms. These data could ultimately be relevant for other related crop plants such as apple trees or cherry trees.