ENGINEERING RESISTANCE AGAINST PLANT-PARASITIC NEMATODES

Plant-parasitic nematodes cause severe damage and economic loss to man y crops. Strategies to manage nematode problems are based on applicati on of chemical compounds, use of resistant cultivars and specific agri cultural practices. Currently, a number of approaches to engineer resi stance against plant-parasitic nematodes also are being developed. Eng ineered resistance may provide protection against nematodes in cases w hen conventional means are not effective enough, too expensive or just not available. Hazardous effects on the environment, as observed with all nematicides, may also be avoided. However, environmental effects from extensive use of transgenic plants are not predictable in all asp ects. Before engineered resistance will be available in crops, a numbe r of molecular problems in the interaction between the host and the ne matode parasite have still to be clarified. Engineered resistance may also raise new problems by indirect effects: it may for example lead t o further intensification of agricultural systems, where nematodes are major pests. The extensive use of resistance may also support the ris e of resistance-breaking populations. As the development of engineered resistance is expensive, profits presumably can be made only with cro ps of high economic importance and protection of patents. Patent prote ction of single genes in cultivars presumably will strongly affect the international seed market.