title: Transcriptional analysis of susceptible and resistant European corn borer strains and their response to Cry1F protoxin.
abstract: BACKGROUND
  Despite a number of recent reports of insect resistance to transgenic crops expressing insecticidal toxins from Bacillus thuringiensis (Bt), little is known about the mechanism of resistance to these toxins. The purpose of this study is to identify genes associated with the mechanism of Cry1F toxin resistance in European corn borer (Ostrinia nubilalis Hübner). For this, we compared the global transcriptomic response of laboratory selected resistant and susceptible O. nubilalis strain to Cry1F toxin. We further identified constitutive transcriptional differences between the two strains.
  
  
  RESULTS
  An O. nubilalis midgut transcriptome of 36,125 transcripts was assembled de novo from 106 million Illumina HiSeq and Roche 454 reads and used as a reference for estimation of differential gene expression analysis. Evaluation of gene expression profiles of midgut tissues from the Cry1F susceptible and resistant strains after toxin exposure identified a suite of genes that responded to the toxin in the susceptible strain (n = 1,654), but almost 20-fold fewer in the resistant strain (n = 84). A total of 5,455 midgut transcripts showed significant constitutive expression differences between Cry1F susceptible and resistant strains. Transcripts coding for previously identified Cry toxin receptors, cadherin and alkaline phosphatase and proteases were also differentially expressed in the midgut of the susceptible and resistant strains.
  
  
  CONCLUSIONS
  Our current study provides a valuable resource for further molecular characterization of Bt resistance and insect response to Cry1F toxin in O. nubilalis and other pest species.
authors.affiliation: Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, USA. neetha@unl.edu.
authors.forename: Neetha
authors.initials: N
authors.lastname: Nanoth Vellichirammal
authors.affiliation: Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, USA. hwang4@unl.edu.
authors.forename: Haichuan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Center for Biotechnology, University of Nebraska-Lincoln, Lincoln, NE, USA. seyun2@unl.edu.
authors.forename: Seong-Il
authors.initials: SI
authors.lastname: Eyun
authors.affiliation: School of Biological Sciences and Center for Plant Science Innovation, University of Nebraska-Lincoln, Lincoln, NE, USA. emoriyama2@unl.edu.
authors.forename: Etsuko N
authors.initials: EN
authors.lastname: Moriyama
authors.affiliation: USDA-ARS, Corn Insects and Crop Genetics Research Unit, Ames, IA, USA. brad.coates@ars.usda.gov.
authors.forename: Brad S
authors.initials: BS
authors.lastname: Coates
authors.affiliation: Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, USA. nick.miller@unl.edu.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Miller
authors.affiliation: Department of Entomology, University of Nebraska-Lincoln, Lincoln, NE, USA. bsiegfried1@unl.edu.
authors.forename: Blair D
authors.initials: BD
authors.lastname: Siegfried
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D059014:High-Throughput Nucleotide Sequencing; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism; D007305:Insecticide Resistance / Q000235:genetics; D007413:Intestinal Mucosa / Q000378:metabolism; D009036:Moths / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D012313:RNA / Q000032:analysis / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction; D017423:Sequence Analysis, RNA; D059467:Transcriptome / Q000187:drug effects*; D003313:Zea mays / Q000235:genetics / Q000378:metabolism
chemical_list: C029103:Bacillus thuringiensis protoxin; D001427:Bacterial Toxins; D019476:Insect Proteins; D011498:Protein Precursors; D012313:RNA