Knockdown of RNA Interference Pathway Genes in Western Corn Rootworms (Diabrotica virgifera virgifera Le Conte) Demonstrates a Possible Mechanism of Resistance to Lethal dsRNA.
RNA interference (RNAi) is being developed as a potential tool for insect pest management. Increased understanding of the RNAi pathway in target insect pests will provide information to use this technology effectively and to inform decisions related to resistant management strategies for RNAi based traits. Dicer 2 (Dcr2), an endonuclease responsible for formation of small interfering RNA's and Argonaute 2 (Ago2), an essential catalytic component of the RNA-induced silencing complex (RISC) have both been associated with the RNAi pathway in a number of different insect species including the western corn rootworm, Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae). We identified both genes from a transcriptome library generated from different tissues and developmental stages of the western corn rootworm, an important target pest for transgenic plants expressing dsRNA targeting essential genes. The expression of these genes was suppressed by more than 90% after injecting gene specific dsRNA into adult rootworms. The injected beetles were then fed vATPase A dsRNA which has previously been demonstrated to cause mortality in western corn rootworm adults. The suppression of both RNAi pathway genes resulted in reduced mortality after subsequent exposure to lethal concentrations of vATPase A dsRNA as well as increased vATPase A expression relative to control treatments. Injections with dsRNA for a non-lethal target sequence (Laccase 2) did not affect mortality or expression caused by vATPase A dsRNA indicating that the results observed with Argo and Dicer dsRNA were not caused by simple competition among different dsRNA's. These results confirm that both genes play an important role in the RNAi pathway for western corn rootworms and indicate that selection pressures that potentially affect the expression of these genes may provide a basis for future studies to understand potential mechanisms of resistance.
Department of Entomology, 103 Entomology Hall, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0816, United States of America.
Ana María
AM
Vélez
Department of Entomology, 103 Entomology Hall, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0816, United States of America.
Chitvan
C
Khajuria
Department of Entomology, 103 Entomology Hall, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0816, United States of America.
Haichuan
H
Wang
Dow AgroSciences, 9330 Zionsville Road, Indianapolis, Indiana 46268, United States of America.
Kenneth E
KE
Narva
University of Florida, Department of Entomology and Nematology, PO Box 110260, Gainesville, Florida 32611, United States of America.
Blair D
BD
Siegfried
D000818:Animals; D060565:Argonaute Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D001517:Coleoptera / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D055785:Gene Knockdown Techniques; D019476:Insect Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010572:Pest Control, Biological; D057865:Plant Immunity / Q000235:genetics; D030821:Plants, Genetically Modified; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics* / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D043244:Ribonuclease III / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D059467:Transcriptome; D025262:Vacuolar Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D003313:Zea mays / Q000235:genetics / Q000276:immunology / Q000469:parasitology
D060565:Argonaute Proteins; D019476:Insect Proteins; D012330:RNA, Double-Stranded; D034741:RNA, Small Interfering; D043244:Ribonuclease III; D025262:Vacuolar Proton-Translocating ATPases