RNAi induced knockdown of a cadherin-like protein (EF531715) does not affect toxicity of Cry34/35Ab1 or Cry3Aa to Diabrotica virgifera virgifera larvae (Coleoptera: Chrysomelidae)

Authors

Sek Yee Tan, Dow AgroSciences, Indianapolis, IN
Murugesan Rangasamy, Dow AgroSciences, Indianapolis, IN
Haichuan Wang, University of Nebraska-LincolnFollow
Ana Maria Vélez, University of Nebraska-LincolnFollow
James Hasler, Dow AgroSciences, Indianapolis, IN
David McCaskill, Dow AgroSciences, Indianapolis, IN
Tao Xu, Dow AgroSciences, Indianapolis, IN
Hong Chen, University of Nebraska-LincolnFollow
Jessica Jurzenski, University of Nebraska-LincolnFollow
Matthew Kelker, Dow AgroSciences, Indianapolis, IN
Xiaoping Xu, Dow AgroSciences, Indianapolis, IN
Kenneth E. Narva, Dow AgroSciencesFollow
Blair D. Siegfried, University of FloridaFollow

Date of this Version

6-2016

Citation

Published in Insect Biochemistry and Molecular Biology 75 (2016) 117–124. doi 10.1016/j.ibmb.2016.06.006

Comments

Copyright © 2016 Elsevier Ltd. Used by permission.

Abstract

The western corn rootworm (WCR), Diabrotica virgifera virgifera LeConte, is an important maize pest throughout most of the U.S. Corn Belt. Bacillus thuringiensis (Bt) insecticidal proteins including modified Cry3Aa and Cry34/35Ab1 have been expressed in transgenic maize to protect against WCR feeding damage. To date, there is limited information regarding the WCR midgut target sites for these proteins. In this study, we examined whether a cadherin-like gene from Diabrotica virgifera virgifera (DvvCad; Gen-Bank accession # EF531715) associated with WCR larval midgut tissue is necessary for Cry3Aa or Cry34/ 35Ab1 toxicity. Experiments were designed to examine the sensitivity of WCR to trypsin activated Cry3Aa and Cry34/35Ab1 after oral feeding of the DvvCad dsRNA to knockdown gene expression. Quantitative real-time PCR confirmed that DvvCad mRNA transcript levels were reduced in larvae treated with cadherin dsRNA. Relative cadherin expression by immunoblot analysis and nano-liquid chromatography–mass spectrometry (nanoLC-MS) of WCR neonate brush border membrane vesicle (BBMV) preparations exposed to DvvCad dsRNA confirmed reduced cadherin expression when compared to BBMV from untreated larvae. However, the larval mortality and growth inhibition of WCR neonates exposed to cadherin dsRNA for two days followed by feeding exposure to either Cry3Aa or Cry34/35Ab1 for four days was not significantly different to that observed in insects exposed to either Cry3Aa or Cry34/35Ab1 alone. In combination, these results suggest that cadherin is unlikely to be involved in the toxicity of Cry3Aa or Cry34/35Ab1 to WCR.