a1 Unité Mixte de Recherche ENSAR-INRA, Amélioration des plantes et biotechnologies végétales - Domaine de la Motte, BP 35327, 35653 Le Rheu Cedex, France
a2 UFR-GAP INRA Montpellier, Domaine de Melgueil, 34130 Mauguio, France
Crop-to-wild gene flow has received close attention over the past ten years in connection with the development and cultivation of transgenic crops. In this paper, we review key examples of crop/wild sympatry and overlapping flowering phenology, pollen and seed dispersal, the barriers to hybridisation and introgression, the evolution and fate of interspecific hybrids, their fitness, and the potential cost of transgenes. We pay particular attention to ways in which the evolution and divergence between crops and their wild relatives may interfere with these successive steps. Our review suggests that crop-to-weed gene flow is highly idiosyncratic and that crop gene dispersion will certainly be very difficult to preclude totally. Future directions for research should thus focus on the long-term establishment and effects of transgenes on natural communities.
(Online publication January 15 2003)