Application of gene silencing for nematode control

Abstract

Root lesion nematodes (Pratylenchus spp., RLNs) are major pests of most crops, and reduce yields of wheat in Western Australia by up to 15%, with Australia-wide losses of more than $36 million per annum. The aim of this project is to investigate the use of RNA interference (RNAi) as an approach to confer resistance to RLNs. RNAi is a well established technology that can be used to silence specific genes in animals and plants. Exposure to artificially introduced double-stranded RNA (dsRNA) leads to the silencing of endogenous genes with homologous sequence. RNAi can silence genes in Caenorhabditis elegans, and some success has been reported in root-knot nematodes. There is no evidence yet that RNAi works for RLNs. RLNs are migratory endoparasitic nematodes, and so mobility is an important aspect of parasitism. In this study, we are investigating genes involved in locomotion in RLNs via RNAi. We have shown that P.thornei and P.zeae are indeed amenable to RNAi. Exposure to dsRNA for locomotion specific genes by 14 hours soaking in medium containing M9 buffer with 50 mM octopamine, 3 mM spermidine and 0.05% gelatin led to locomotion impairment in both of these species. In addition, dsRNA originating from P.thornei also led to abnormalities in the closely related species P.zeae and vice versa, indicating that inter-species gene knockdown is possible. The outcome of this study is economically significant as no reported natural resistance genes have broad effectiveness against RLNs. Bioengineered crops expressing dsRNA that silence essential target genes to interrupt the parasitic process represents a potential approach to develop novel, broadly applicable and durable RLN-resistance in crop plants