Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2008
Publication Date: 12/8/2008
Citation: Patel, N., Hamamouch, N., Li, C., Hussey, R., Mitchum, M.G., Baum, T., Wang, X., Davis, E.L. 2008. Similarity and functional analyses of expressed parasitism genes in Heterodera schachtii and Heterodera glycines. Journal of Nematology. 40(4):299-310. Interpretive Summary: Plant-parasitic nematodes are important agricultural pests that cause significant economic losses. In order to successfully parasitize host roots, nematodes secrete proteins that transform plant cells into a specialized site for the nematode to feed. Understanding the function of nematode parasitism genes encoding these secreted proteins will be very useful for identifying nematode targets to develop novel nematode control strategies. RNA interference (RNAi) is a gene silencing process triggered by double-stranded RNA (dsRNA). Recent studies have indicated that the expression in a host plant of dsRNA targeting nematode parasitism genes may generate broad or enhanced resistance to nematode infection. In this study, we showed that host-derived RNAi of Hssyv46, but not Hs4e02 or Hs5d08 resulted in partial resistance to nematode infection, suggesting that the parasitism protein HsSYV46 may have an important role in nematode parasitism and that novel nematode resistance might be developed by targeting the Hssyv46 gene.
Technical Abstract: The secreted proteins encoded by “parasitism genes” expressed within the esophageal glands cells of cyst nematodes play important roles in plant parasitism. Homologous transcripts and encoded proteins of the Heterodera glycines pioneer parasitism genes Hgsyv46, Hg4e02 and Hg5d08 were identified and similarly expressed within the esophageal glands cells of Heterodera schachtii. Constitutive expression of Hs4E02 and Hs5D08 in transgenic Arabidopsis thaliana did not produce any visible phenotypic changes in plant growth and development nor affect the number of H. schachtii females that developed on roots of those plants. Constitutive and nematode-inducible Arabidopsis expression of double-stranded RNA complementary to Hssyv46, a parasitism gene with function similar to plant CLAVATA3/ESR peptides, resulted in a significant (P=0.05) 36% decrease in H. schachtii female numbers and significant host-derived RNA interference-mediated silencing of Hssyv46 transcript levels in nematodes excised from those roots. Significant and specific effects of Arabidopsis host-derived RNAi complementary to Hs5d08 or Hs4e02 on H. schachtii female development were not observed, however, up to 20% reduction in H. schachtii female numbers were observed in roots of these plants.