title: Downregulation and mutation of a Cadherin gene associated with Cry1Ac resistance in the Asian Corn Borer, Ostrinia furnacalis (Guenée).
abstract: Development of resistance in target pests is a major threat to long-term use of transgenic crops expressing Bacillus thuringiensis (Bt) Cry toxins. To manage and/or delay the evolution of resistance in target insects through the implementation of effective strategies, it is essential to understand the basis of resistance. One of the most important mechanisms of insect resistance to Bt crops is the alteration of the interactions between Cry toxins and their receptors in the midgut. A Cry1Ac-selected strain of Asian corn borer (ACB), Ostrinia furnacalis, a key pest of maize in China, evolved three mutant alleles of a cadherin-like protein (OfCAD) (MPR-r1, MPR-r2 and MPR-r3), which mapped within the toxin-binding region (TBR). Each of the three mutant alleles possessed two or three amino acid substitutions in this region, especially Thr1457→Ser. In highly resistant larvae (ACB-Ac200), MPR-r2 had a 26-amino acid residue deletion in the TBR, which resulted in reduced binding of Cry1Ac compared to the MPR from the susceptible strain, suggesting that the number of amino acid deletions influences the level of resistance. Furthermore, downregulation of OfCAD gene (ofcad) transcription was observed in the Cry1Ac resistant strain, ACB-Ac24, suggesting that Cry1Ac resistance in ACB is associated with the downregulation of the transcript levels of the cadherin-like protein gene. The OfCAD identified from ACB exhibited a high degree of similarity to other members of the cadherin super-family in lepidopteran species.
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China. jintingting492@126.com.
authors.forename: Tingting
authors.initials: T
authors.lastname: Jin
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China. cx1981@cjaas.com.
authors.forename: Xue
authors.initials: X
authors.lastname: Chang
authors.affiliation: Newcastle Institute for Research on Sustainability, School of Biology, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK. a.m.r.gatehouse@newcastle.ac.uk.
authors.forename: Angharad M R
authors.initials: AM
authors.lastname: Gatehouse
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China. zywang@ippcaas.cn.
authors.forename: Zhenying
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Newcastle Institute for Research on Sustainability, School of Biology, University of Newcastle, Newcastle upon Tyne NE1 7RU, UK. martin.edwards@newcastle.ac.uk.
authors.forename: Martin G
authors.initials: MG
authors.lastname: Edwards
authors.affiliation: The State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China. klhe@ippcaas.cn.
authors.forename: Kanglai
authors.initials: K
authors.lastname: He
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics; D015820:Cadherins / Q000737:chemistry / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D015536:Down-Regulation; D004731:Endotoxins / Q000235:genetics; D006460:Hemolysin Proteins / Q000235:genetics; D019476:Insect Proteins / Q000235:genetics*; D007305:Insecticide Resistance / Q000235:genetics*; D007306:Insecticides; D007915:Lepidoptera / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010572:Pest Control, Biological
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; D018076:DNA, Complementary; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis