Nematode resistance.

Plant-parasitic nematodes are major pests of both temperate and tropical agriculture. Many of the most damaging species employ an advanced parasitic strategy in which they induce redifferentiation of root cells to form specialized feeding structures able to support nematode growth and reproduction over several weeks. Current control measures, particularly in intensive agriculture systems, rely heavily on nematicides but alternative strategies are required as effective chemicals are withdrawn from use. Here, we review the different approaches that are being developed to provide resistance to a range of nematode species. Natural, R gene-based resistance is currently exploited in traditional breeding programmes and research is ongoing to characterize the molecular basis for the observed resistant phenotypes. A number of transgenic approaches hold promise, the best described being the expression of proteinase inhibitors to disrupt nematode digestion. The application of plant-delivered RNA interference (RNAi) to silence essential nematode genes has recently emerged as a potentially valuable resistance strategy.