Genetic resistance to nematodes: where is it useful?

Genetic resistance has been used to control nematodes of some crops. There are many more published reports of resistance than of successful use of resistant cultivars for management of nematode populations. Possible explanations for this apparent discrepancy are explored in relation to making better use of naturally occurring genetic resistance in more crops. Analysis of the use of resistance emphasises that the extent of genetic variation in host crop and pest nematode populations are very important determinants of durable resistance. Single dominant resistant genes in pure line crops are likely to provide durable control only in unusual situations. Human impacts on plant genetic variation during the relatively recent domestication of crops and their current use in industrialised farming have also affected nematode variation. Moreover, the timeframe, spatial scales and likely nature of plant-nematode co-evolution in the longer period preceding domestication further emphasise the significance and extent of the genetic complexity of the interactions. It is important to take these factors into account during the identification of resistance sources and their exploitation through plant breeding.