Characterization of plant nematode genes: identifying targets for a transgenic defence

Current control of plant parasitic nematodes often relies on highly toxic and environmentally harmful nematicides. As their use becomes increasingly restricted there is an urgent need to develop crop varieties with resistance to nematodes. The limitations surrounding conventional plant breeding ensure there is a clear opportunity for transgenic resistance to lessen current dependence on chemical control. The increasing use of molecular biology techniques in the field of plant nematology is now providing useful information for the design of novel defences to meet the new needs. Plant responses to parasitism are being investigated at the molecular level and nematode gene products that could be targets for a direct anti-nematode defence are being characterized. The potential of an anti-feedant approach to nematode control has been demonstrated. It is based on the transgenic expression of proteinase inhibitors. The rational development of this strategy involves characterization of nematode proteinase genes and optimization of inhibitors by protein engineering. Durability of the resistance can be enhanced by stacking transgenes directed at different nematode targets.