title: Cross-resistance studies of Cry1Ac-resistant strains of Helicoverpa armigera (Lepidoptera: Noctuidae) to Cry2Ab.
abstract: Bioassays and binding tests between Cry toxins (CrylAa, CrylAb, CrylAc, and Cry2Ab) and brush-border membrane vesicles (BBMVs) from larvae of a Bacillus thurningiensis (Bt)-susceptible (96S) and two CrylAc-resistant strains (BtR and LFR10) were conducted for investigating cross-resistance of CrylAc-resistant strains to Cry2Ab in Helicoverpa armigera (Hiibner) (Lepidoptera: Noctuidae). The resistance ratio (RR) values of the BtR and LFR10 strains to CrylAc and Cry2Ab were 2,971- and 1.1-fold and 253- and 1.0-fold, respectively, indicating that there was no cross-resistance to Cry2Ab. The binding experiments between Cry toxins and BBMVs from BtR, LFR10, and 96S larvae showed that all of the toxins could bind with these BBMVs, but the Cry2Ab could not displace 125I labeled CrylAc and CrylAb. The same results were observed in reciprocal binding tests, demonstrating that CrylA and Cry2Ab had different binding sites in H. armigera and providing a potential mechanism for the lack of cross-resistance between CrylA and Cry2Ab toxins. These results suggest that the transgenic cotton, Gossypium hirsutum L., expressing CrylAc and Cry2Ab genes may be deployed for management of CrylAc resistant H. armigera.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, China.
authors.forename: Shudong
authors.initials: S
authors.lastname: Luo
authors.forename: Kongming
authors.initials: K
authors.lastname: Wu
authors.forename: Yan
authors.initials: Y
authors.lastname: Tian
authors.forename: Gemei
authors.initials: G
authors.lastname: Liang
authors.forename: Xue
authors.initials: X
authors.lastname: Feng
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Yuyuan
authors.initials: Y
authors.lastname: Guo
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism; D001667:Binding, Competitive; D001681:Biological Assay; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism; D003368:Gossypium / Q000235:genetics; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism; D007305:Insecticide Resistance; D007306:Insecticides / Q000378:metabolism; D008871:Microvilli / Q000378:metabolism; D009036:Moths / Q000378:metabolism; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000633:toxicity
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis