| Abstract: | Cyst nematodes are highly evolved sedentary plant endoparasitesthat use parasitism proteins injected through the stylet intohost tissues to successfully parasitize plants. These secretoryproteins likely are essential for parasitism as they are involvedin a variety of parasitic events leading to the establishmentof specialized feeding cells required by the nematode to obtainnourishment. With the advent of RNA interference (RNAi) technologyand the demonstration of host-induced gene silencing in parasites,a new strategy to control pests and pathogens has become available,particularly in root-knot nematodes. Plant host-induced silencingof cyst nematode genes so far has had only limited success butsimilarly should disrupt the parasitic cycle and render thehost plant resistant. Additional in planta RNAi data for cystnematodes are being provided by targeting four parasitism genesthrough host-induced RNAi gene silencing in transgenic Arabidopsisthaliana, which is a host for the sugar beet cyst nematode Heteroderaschachtii. Here it is reported that mRNA abundances of targetednematode genes were specifically reduced in nematodes feedingon plants expressing corresponding RNAi constructs. Furthermore,this host-induced RNAi of all four nematode parasitism genesled to a reduction in the number of mature nematode females.Although no complete resistance was observed, the reductionof developing females ranged from 23% to 64% in different RNAilines. These observations demonstrate the relevance of the targetedparasitism genes during the nematode life cycle and, potentiallymore importantly, suggest that a viable level of resistancein crop plants may be accomplished in the future using thistechnology against cyst nematodes. Key words: beet cyst nematode (BCN), soybean cyst nematode (SCN), host induced, in planta RNAi, resistance, RNAi, transgenic
Received 19 August 2008; Revised 25 October 2008 Accepted 27 October 2008 |
