title: A Single Point Mutation Resulting in Cadherin Mislocalization Underpins Resistance againstBacillus thuringiensisToxin in Cotton Bollworm.
abstract: Transgenic plants that produceBacillus thuringiensis(Bt) crystalline (Cry) toxins are cultivated worldwide to control insect pests. Resistance toB. thuringiensistoxins threatens this technology, and although different resistance mechanisms have been identified, some have not been completely elucidated. To gain new insights into these mechanisms, we performed multiple back-crossing from a 3000-fold Cry1Ac-resistant BtR strain from cotton bollworm (Helicoverpa armigera), isolating a 516-fold Cry1Ac-resistant strain (96CAD). Cry1Ac resistance in 96CAD was tightly linked to a mutant cadherin allele (mHaCad) that contained 35 amino acid substitutions compared with HaCad from a susceptible strain (96S). We observed significantly reduced levels of the mHaCad protein on the surface of the midgut epithelium in 96CAD as compared with 96S. Expression of both cadherin alleles from 96CAD and 96S in insect cells and immunofluorescence localization in insect midgut tissue sections showed that the HaCAD protein from 96S localizes on the cell membrane, whereas the mutant 96CAD-mHaCad was retained in the endoplasmic reticulum (ER). Mapping of the mutations identified a D172G substitution mainly responsible for cadherin mislocalization. Our finding of a mutation affecting membrane receptor trafficking represents an unusual and previously unrecognizedB. thuringiensisresistance mechanism.
authors.affiliation: From the State Key Laboratory for Biology of Plant Disease and Insect Pests, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China.|the Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China.
authors.forename: Yutao
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: the College of Life Science, Central China Normal University, No. 152 Luoyu Avenue, Wuhan 430079, China, and.
authors.forename: Qing
authors.initials: Q
authors.lastname: Dai
authors.affiliation: From the State Key Laboratory for Biology of Plant Disease and Insect Pests, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China.|the College of Life Science, Central China Normal University, No. 152 Luoyu Avenue, Wuhan 430079, China, and.
authors.forename: Ruqin
authors.initials: R
authors.lastname: Hu
authors.affiliation: the Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico.
authors.forename: Sabino
authors.initials: S
authors.lastname: Pacheco
authors.affiliation: the College of Life Science, Central China Normal University, No. 152 Luoyu Avenue, Wuhan 430079, China, and.
authors.forename: Yongbo
authors.initials: Y
authors.lastname: Yang
authors.affiliation: From the State Key Laboratory for Biology of Plant Disease and Insect Pests, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China.
authors.forename: Gemei
authors.initials: G
authors.lastname: Liang
authors.affiliation: the Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico.
authors.forename: Mario
authors.initials: M
authors.lastname: Soberón
authors.affiliation: the Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, Cuernavaca 62250, Morelos, Mexico.
authors.forename: Alejandra
authors.identifier: 0000-0002-7573-7475
authors.initials: A
authors.lastname: Bravo
authors.affiliation: the College of Life Science, Central China Normal University, No. 152 Luoyu Avenue, Wuhan 430079, China, and liukaiyu@mail.ccnu.edu.cn.
authors.forename: Kaiyu
authors.identifier: 0000-0002-3810-4572
authors.initials: K
authors.lastname: Liu
authors.affiliation: From the State Key Laboratory for Biology of Plant Disease and Insect Pests, Chinese Academy of Agricultural Sciences, West Yuanmingyuan Road, Beijing 100193, China, wukongming@caas.cn.
authors.forename: Kongming
authors.identifier: 0000-0003-2499-1032
authors.initials: K
authors.lastname: Wu
mesh_terms: D000483:Alleles; D019943:Amino Acid Substitution; D000818:Animals; D001413:Bacillus thuringiensis / Q000378:metabolism*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000633:toxicity*; D015820:Cadherins / Q000235:genetics*; D002460:Cell Line; D004731:Endotoxins / Q000235:genetics / Q000633:toxicity*; D049452:Green Fluorescent Proteins / Q000235:genetics; D006460:Hemolysin Proteins / Q000235:genetics / Q000633:toxicity*; D009036:Moths / Q000187:drug effects* / Q000235:genetics; D010572:Pest Control, Biological; D017354:Point Mutation; D014158:Transcription, Genetic
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D049452:Green Fluorescent Proteins
keywords: Bacillus thuringiensis; Cry1Ac; Helicoverpa armigera; antibiotic resistance; bacterial toxin; insect; mutant; plasma membrane; receptor modification; receptor trafficking