title: A Transformed Bacterium Expressing Double-Stranded RNA Specific to Integrin β1 Enhances Bt Toxin Efficacy against a Polyphagous Insect Pest, Spodoptera exigua.
abstract: BACKGROUND
  Oral toxicity of double-stranded RNA (dsRNA) specific to integrin β1 subunit (SeINT) was known in a polyphagous insect pest, Spodoptera exigua. For an application of the dsRNA to control the insect pest, this study prepared a transformed Escherichia coli expressing dsRNA specific to SeINT.
  
  
  RESULTS
  The dsRNA expression was driven by T7 RNA polymerase overexpressed by an inducer in the transformed E. coli. The produced dsRNA amount was proportional to the number of the cultured bacteria. The transformed bacteria gave a significant oral toxicity to S. exigua larvae with a significant reduction of the SeINT expression. The resulting insect mortality increased with the fed number of the bacteria. Pretreatment with an ultra-sonication to disrupt bacterial cell wall/membrane significantly increased the insecticidal activity of the transformed bacteria. The larvae treated with the transformed bacteria suffered tissue damage in the midgut epithelium, which exhibited a marked loss of cell-cell contacts and underwent a remarkable cell death. Moreover, these treated larvae became significantly susceptible to a Cry toxin derived from Bacillus thuringiensis (Bt).
  
  
  CONCLUSIONS
  This study provides a novel and highly efficient application technique to use dsRNA specific to an integrin gene by mixing with a biopesticide, Bt.
authors.affiliation: Department of Bioresource Sciences, Andong National University, Andong, 760-749, Republic of Korea.
authors.forename: Eunseong
authors.initials: E
authors.lastname: Kim
authors.affiliation: Department of Bioresource Sciences, Andong National University, Andong, 760-749, Republic of Korea.
authors.forename: Youngjin
authors.initials: Y
authors.lastname: Park
authors.affiliation: Department of Bioresource Sciences, Andong National University, Andong, 760-749, Republic of Korea.
authors.forename: Yonggyun
authors.initials: Y
authors.lastname: Kim
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D015870:Gene Expression; D007306:Insecticides / Q000378:metabolism; D019012:Integrin beta1 / Q000235:genetics*; D007413:Intestinal Mucosa / Q000378:metabolism / Q000382:microbiology; D010572:Pest Control, Biological; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics*; D018411:Spodoptera / Q000235:genetics* / Q000382:microbiology; D014118:Toxins, Biological / Q000235:genetics*; D014169:Transformation, Bacterial
chemical_list: D007306:Insecticides; D019012:Integrin beta1; D012330:RNA, Double-Stranded; D014118:Toxins, Biological