Control of Root Knot Nematodes by Transgenic RNA Interference

Non Technical Summary: The goal of this research is to generate transgenic crops with broad-spectrum, season-long resistance to root knot nematode (RKN, Meloidogyne sp.). Plant parasitic nematodes, of which RKN is the most significant, annually cause damage of $8 billion in the U.S. and $78 billion worldwide. This project proposes to use RNA interference (RNAi) to control RKN by silencing nematode genes in planta. We will generate and test the efficacy of specific double-stranded RNAs (dsRNAs) which can be delivered to RKN to inhibit essential target genes and block parasite development in the host. Divergence has already established an efficient transgenic hairy root in planta expression system and used it to screen numerous candidate dsRNAs for soybean cyst nematode (SCN) genes. Promising results in SCN control have been achieved, and the same system has been utilized successfully for RKN in pilot experiments. We will select, clone, and sequence RKN gene targets likely to be both conserved and essential in all RKN species. The RNAi potency of RKN target genes will be assayed in the transgenic hairy roots. At the conclusion of Phase I, we anticipate that several target genes demonstrating substantial reduction in RKN reproduction in hairy root will be selected for whole plant transformation during Phase II. Transgenic crops have a significant opportunity to replace toxic nematicidal pesticides being withdrawn from the market. Benefits of a successful transgenic approach would include higher grower yields, lower input costs, greater worker safety, and less environmental impact.