Abstract
The evolution of insect resistance threatens the effectiveness of Bacillus thuringiensis (Bt) toxins that are widely used in sprays and transgenic crops. Resistance to Bt toxins in some insects is linked with mutations that disrupt a toxin-binding cadherin protein. We show that susceptibility to the Bt toxin Cry1Ab was reduced by cadherin gene silencing with RNA interference in Manduca sexta, confirming cadherin's role in Bt toxicity. Native Cry1A toxins required cadherin to form oligomers, but modified Cry1A toxins lacking one alpha-helix did not. The modified toxins killed cadherin-silenced M. sexta and Bt-resistant Pectinophora gossypiella that had cadherin deletion mutations. Our findings suggest that cadherin promotes Bt toxicity by facilitating toxin oligomerization and demonstrate that the modified Bt toxins may be useful against pests resistant to standard Bt toxins.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
MeSH terms
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Animals
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Bacillus thuringiensis Toxins
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics*
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Bacterial Proteins / metabolism
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Bacterial Proteins / toxicity*
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Bacterial Toxins / chemistry
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Bacterial Toxins / genetics*
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Bacterial Toxins / metabolism
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Bacterial Toxins / toxicity*
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Cadherins / genetics
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Cadherins / metabolism
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Endotoxins / chemistry
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Endotoxins / genetics*
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Endotoxins / metabolism
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Endotoxins / toxicity*
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Genetic Engineering
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Hemolysin Proteins / chemistry
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Hemolysin Proteins / genetics*
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Hemolysin Proteins / metabolism
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Hemolysin Proteins / toxicity*
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Insecticide Resistance*
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Larva
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Manduca* / genetics
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Manduca* / metabolism
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Moths* / genetics
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Moths* / metabolism
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Mutation
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Pest Control, Biological*
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RNA Interference
Substances
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Bacillus thuringiensis Toxins
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Bacterial Proteins
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Bacterial Toxins
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Cadherins
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Endotoxins
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Hemolysin Proteins
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insecticidal crystal protein, Bacillus Thuringiensis