Binding of three Cry1A toxins in resistant and susceptible strains of cotton bollworm (Helicoverpa armigera) |
| |
Authors: | Shudong Luo Guirong Wang Kong Ming Wu Lianyang Bai Yuyuan Guo |
| |
Institution: | a State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100094, PR China b College of Bio-safety Science and Technology, Hunan Agricultural University, Changsha 410128, PR China |
| |
Abstract: | Evolution of resistance by pests is the greatest threat to the continuous success of theBacillus thuringiensis (Bt) toxins used in conventional sprays or in transgenic plants. The most common mechanism of insect resistance to Bt is reduced binding of toxins to target sites in the brush border membrane of the larval mid-gut. In this paper, binding experiments were performed with three 125I-Cry1A toxins and the brush border membrane vesicles from Cry1Ac resistant or susceptible strains of Helicoverpa armigera. The homologous competition test showed that there was no significant difference in Cry1Ac-binding affinity, but the concentration of Cry1Ac-binding sites dramatically decreased in the resistant strain (Rt decreased from 5.87 ± 1.40 to 2.23 ± 0.80). The heterologous competition test showed that there were three Cry1Ac-binding sites in the susceptible strain. Among them, site 1 bound with all three Cry1A toxins, site 2 bound with both Cry1Ab and Cry1Ac, and site 3 only bound with Cry1Ac. In the Cry1Ac resistant strain, the binding capability of site 1 with Cry1Ab decreased and site 2 did not bind with Cry1Ac. It is suggested that the absence of one binding site is responsible for H. armigera resistance to Cry1Ac. This result also showed that the resistance fitted the “mode 1” pattern of Bt resistance described previously. |
| |
Keywords: | Helicoverpa armigera Cry1A toxins Binding site Binding model Resistance |
本文献已被 ScienceDirect 等数据库收录! |
|