Submitted to: Insect Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/20/2008
Publication Date: 12/1/2008
Citation: Coates, B.S., Sumerford, D.V., Hellmich II, R.L., Lewis, L.C. 2008. Mining an Ostrinia nubilalis Midgut Expressed Sequence Tag (EST) Library for Candidate Genes and Single Nucleotide Polymorphisms (SNPs). Insect Molecular Biology. 17(6):607-620. Interpretive Summary: European corn borer (ECB) is a major pest of corn in the central United States. Damage and control costs for this insect exceed $1 billion from an annual crop valued at more than $22 billion. New technologies, primarily genetically-engineered (transgenic) corn containing insecticidal Bacillus thuringiensis (Bt) genes, have been designed to control ECB larvae. Scientists and crop producers are excited about these plants because they offer an effective way to kill pests without the need for excessive conventional chemical insecticides. An important part of managing resistance to transgenic products is the need to elucidate Bt resistance mechanisms and the role of alternative ECB host plants. Chemical properties of the ECB midgut, especially the molecular properties of enzymes, will play a major role in both ECB resistance to transgenic corn as well as the utilization of host plants by ECB larvae. In this study, genes expressed in the gut tissue of ECB larvae were sampled, and genes previously shown to be involved in resistance to Bt were identified. The sampling also identified many new genes from ECB that are candidate genes involved in Bt resistance mechanisms. This research provides a molecular tool for description of gene expression in ECB midguts and another tool to assess their possible involvement in Bt resistance. Slowing the development of Bt resistance by using diagnostic molecular tools will provide greater, sustainable control of ECB larvae and decrease operational costs for corn producers by eliminating the need for costly conventional insecticides to control Bt-resistant larvae.
Technical Abstract: European corn borer, Ostrinia nubilalis, larvae feed upon many plant hosts and are a major target for genetically-engineered corn expressing Bacillus thuringiensis (Bt) toxins. DNA sequencing of a non-normalized O. nubilalis larval midgut cDNA library (ARS-CICGRU ONmgEST) identified 535 unique sequences from 1745 clones, of which 296 sequences were singletons. A total of 367 sequences (21.0% of total; 31.1% of unique sequences) had no significant matches to GenBank or Bombyx mori EST (Expressed Sequence Tag) database accessions. Phylogenetic analysis of peptide sequences derived from EST open reading frames identified 12 serine protease and 8 lipase gene families. Multimember gene families and candidate Bt resistance genes were identified from O. nubilalis ESTs and are tools for lepidopteran genomics.