The Evolution of a Biological Risk Program: Gene flow between Wheat (Triticum aestivum L.) and Jointed Goatgrass (Aegilops cylindrica Host)

The development of a biological risk program to determine the potential for gene flow between a cultivated species to a wild species involves a series of steps that lead from determining if there is a problem to developing ways to minimize the potential for undesirable gene flow. In the case of wheat and jointed goatgrass the presence of seed on hybrids between the two species in the field led to the initial studies to determine if there was the potential for gene flow by backcrossing to jointed goatgrass. Greenhouse and field studies confirmed that not only was backcrossing possible but that partial self-fertility could be restored in the second backcross generation. This indicated that gene movement between the two species would be possible in the field with the hybrid acting as a bridge for gene transfer. Once the potential for gene flow was confirmed, studies were then initiated to determining ways to minimize gene movement. In the case of wheat and jointed goatgrass it may be possible to reduce the transfer and retention of wheat genes in a jointed goatgrass background by locating the gene in wheat on a genome not shared with jointed goatgrass, and by using cultural practices to prevent the hybrid or BC1 generation reducing the potential for restoration of self-fertility. These methods may reduce the potential for gene flow but it would still need to be determined if they reduce the risk to 'an acceptable level'.