Bacillus thuringiensis Cry1A toxins exert toxicity by multiple pathways in insects

Adoption of biotech crops engineered to express insecticidal toxins from Bacillus thuringiensis (Bt) has revolutionized insect pest control in agriculture. For continuing effective application and development of the environmentally friendly Bt biotechnology, it is fundamental to understand pathways...

Full description

Saved in:
Bibliographic Details
Published in:Insect biochemistry and molecular biology 2018-11, Vol.102, p.59-66
Main Authors: Wang, Shaohua, Kain, Wendy, Wang, Ping
Format: Article
Language:English
Subjects:
ABC transporter
Bacillus thuringiensis
Bt toxins
Cadherin
Pathway of toxicity
Trichoplusia ni
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Adoption of biotech crops engineered to express insecticidal toxins from Bacillus thuringiensis (Bt) has revolutionized insect pest control in agriculture. For continuing effective application and development of the environmentally friendly Bt biotechnology, it is fundamental to understand pathways of toxicity of Bt toxins in insects. In this study, mutations were introduced in the midgut cadherin gene in the cabbage looper, Trichoplusia ni, by CRISPR/Cas9 mutagenesis. T. ni strains with mutations in the genes of two major receptors for Bt toxins, the midgut cadherin and ABCC2, and three Cry1A toxins with shared and differential midgut binding sites were used as an experimental system to dissect the roles of the cadherin and ABCC2 in the pathways of toxicity of Bt toxins. Results from assays of responses of the T. ni strains to different Bt toxins revealed that the cadherin and ABCC2 play independent roles in the mode of action of Cry1A toxins and that Bt toxins exert insecticidal activity through multiple redundant pathways of toxicity in insects. Besides the cadherin and ABCC2 pathways, there exists an additional major pathway of toxicity to be identified for Cry1Aa. The results also confirmed that the toxicity of Cry2Ab involves neither the cadherin nor the ABCC2 protein. The multiple pathway model for Bt toxins clarified from this study provided new insights into the molecular modes of action of Bt toxins and mechanisms of insect resistance to Bt toxins. [Display omitted] •Trichoplusia ni strains with mutations in the midgut cadherin gene were generated by CRISPR/Cas9 mutagenesis.•Roles of midgut cadherin and ABCC2 in mode of action of Bt toxins were functionally dissected in T. ni.•The midgut cadherin and ABCC2 play independent roles in the mode of action of Cry1A toxins.•Bt toxins exert insecticidal activity through multiple independent pathways of toxicity in insects.
ISSN:0965-1748
1879-0240
DOI:10.1016/j.ibmb.2018.09.013