Engineering modified Bt toxins to counter insect resistance

Mario Soberón, Liliana Pardo-López, Idalia López, Isabel Gómez, Bruce E. Tabashnik, Alejandra Bravo

Research output: Contribution to journalArticlepeer-review

192 Scopus citations


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 a-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.

Original languageEnglish (US)
Pages (from-to)1640-1642
Number of pages3
Issue number5856
StatePublished - Dec 7 2007

ASJC Scopus subject areas

  • General


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