gene Flow: Implications for Crop Diversity and Wild Relatives

2.3 In what species or kinds of crops couldtransgene flow occur?Almost all of the world’s most important crop plants are knownto hybridise with wild relatives. At least 44 cultivated cropshave demonstrated the capacity for hybridisation with wild andweedy relatives, including 12 of the 13 most widely cultivatedcrops (Ellstrand et al. 1999), and 11 of the 20 most importantUS crops, including sunflower, radish, sorghum, canola, squash,rice, wheat, sugar beet, lettuce, poplar, strawberry, and bentgrass(Ellstrand 2003). As discussed, gene flow to wild relatives andlandraces will depend on the availability of such species nearthe area of cultivation (Messeguer 2003). Crop-to-crop genetransfer often occurs where transgenic and non-transgenic cropsare planted in close proximity. Many of these crop plants areprimarily outcrossing species, including maize, canola (rapeseed),tomato, sorghum, wheat, sugar beet, alfalfa, cucumber, radish,and strawberries (NRC 2000).7