title: Searching for gene flow from cultivated to wild strawberries in Central Europe.
abstract: OBJECTIVE
  Experimental crosses between the diploid woodland strawberry (Fragaria vesca L.) and the octoploid garden strawberry (F. × ananassa Duch.) can lead to the formation of viable hybrids. However, the extent of such hybrid formation under natural conditions is unknown, but is of fundamental interest and importance in the light of the potential future cultivation of transgenic strawberries. A hybrid survey was therefore conducted in the surroundings of ten farms in Switzerland and southern Germany, where strawberries have been cultivated for at least 10 years and where wild strawberries occur in the close vicinity.
  
  
  METHODS
  In 2007 and 2008, 370 wild F. vesca plants were sampled at natural populations around farms and analysed with microsatellite markers. In 2010, natural populations were revisited and morphological traits of 3050 F. vesca plants were inspected. DNA contents of cell nuclei of morphologically deviating plants were estimated by flow cytometry to identify hybrids. As controls, 50 hybrid plants from interspecific hand-crosses were analysed using microsatellite analysis and DNA contents of cell nuclei were estimated by flow cytometry.
  
  
  RESULTS
  None of the wild samples collected in 2007 and 2008 contained F. × ananassa microsatellite markers, while all hybrids from hand-crosses clearly contained markers of both parent species. Morphological inspection of wild populations carried out in 2010 and subsequent flow cytometry of ten morphologically deviating plants revealed no hybrids.
  
  
  CONCLUSIONS
  Hybrid formation or hybrid establishment in natural populations in the survey area is at best a rare event.
authors.affiliation: Department of Environmental Sciences, Section Conservation Biology (NLU), University of Basel, St. Johanns-Vorstadt 10, Basel, Switzerland.
authors.forename: Juerg
authors.initials: J
authors.lastname: Schulze
authors.forename: Peter
authors.initials: P
authors.lastname: Stoll
authors.forename: Alex
authors.initials: A
authors.lastname: Widmer
authors.forename: Andreas
authors.initials: A
authors.lastname: Erhardt
mesh_terms: D000383:Agriculture; D000483:Alleles; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D003625:Data Collection; D005060:Europe; D031985:Fragaria / Q000235:genetics* / Q000254:growth & development*; D051456:Gene Flow / Q000235:genetics*; D005819:Genetic Markers; D006239:Haplotypes / Q000235:genetics; D018895:Microsatellite Repeats / Q000235:genetics; D011157:Population Dynamics; D017422:Sequence Analysis, DNA
chemical_list: D005819:Genetic Markers