Submitted to: Insect Biochemistry and Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/22/2004
Publication Date: 2/1/2005
Citation: Coates, B.S., Sumerford, D.V., Hellmich, II, R.L., Lewis, L.C. 2005. Sequence variation in the cadherin gene of Ostrinia nubilalis: A tool for field monitoring. Insect Biochemistry and Molecular Biology. 35:129-139. Interpretive Summary: Several types of genetically-engineered (transgenic) plants have been produced that kill insects when they feed. Scientists and crop producers are excited about these plants because they offer an effective way to kill pests without conventional chemical insecticides. Reduced chemical usage translates into less surface and ground water contamination. European corn borer, an important pest of corn in the United States, is controlled by transgenic corn. Damage and control costs for this insect exceed $1 billion from an annual crop valued at more than $22 billion. Nearly complete control of European corn borer on Bt transgenic corn, however, has many scientists concerned that this pest could become resistant to these plants. In this study, a gene called cadherin was isolated and identified that may be involved in potential insect resistance to Bt corn. This research provides a molecular tool for characterization of possible resistance genes. The genetics of insect resistance will be useful for all stakeholders interested in finding novel ways to control European corn borers and sustain Bt technology.
Technical Abstract: Toxin-binding proteins of insect midgut epithelial cells are associated with insect resistance to Bacillus thuringiensis (Bt) Cry toxins. A 5378 nt cDNA encoding a 1717 amino acid putative midgut cadherin-like glycoprotein and candidate Cry1Ab toxin-binding protein was characterized from Ostrinia nubilalis. Intraspecific alignment of partial O. nubilalis cadherin gene sequences identified variance within proposed Cry1A toxin binding region 2 (TBR2), 1328IPLQTSILVVT[I/V] N1340, and flanking Cry1A toxin binding region 1 (TBR1), 861DIEIEIIDTNN871. DNA sequence and PCR-RFLP detected single nucleotide polymorphism (SNP) between cadherin alleles, and pedigree analysis demonstrated Mendelian inheritance. A population sample from Mead, Nebraska showed high heterozygosity, and Hardy-Weinberg equilibrium (HWE) of TBR1 but not TBR2 PCR-RFLP alleles. Assays for O. nubilalis cadherin genotyping may be useful for future resistance monitoring and linkage mapping of candidate resistance genes.