Binding of Bacillus thuringiensis toxins in resistant and susceptible strains of pink bollworm (Pectinophora gossypiella)

Joel Gonzátlez-Cabrera, Baltasar Escriche, Bruce E. Tabashnik, Juan Ferré

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

Evolution of resistance by pests could cut short the success of transgenic plants producing toxins from Bacillus thuringiensis, such as Bt cotton. The most common mechanism of insect resistance to B. thuringiensis is reduced binding of toxins to target sites in the brush border membrane of the larval midgut. We compared toxin binding in resistant and susceptible strains of Pectinophora gossypiella, a major pest of cotton worldwide. Using Cry1Ab and Cry1Ac labeled with 125I and brush border membrane vesicles (BBMV), competition experiments were performed with unlabeled Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry1Ca, Cry1Ja, Cry2Aa, and Cry9Ca. In the susceptible strain, Cry1Aa, Cry1Ab, Cry1Ac, and Cry1Ja bound to a common binding site that was not shared by the other toxins tested. Reciprocal competition experiments with Cry1Ab, Cry1Ac, and Cry1Ja showed that these toxins do not bind to any additional binding sites. In the resistant strain, binding of 125I-Cry1Ac was not significantly affected; however, 125I-Cry1Ab did not bind to the BBMV. This result, along with previous data from this strain, shows that the resistance fits the "mode 1" pattern of resistance described previously in Plutella xylostella, Plodia interpunctella, and Heliothis virescens.

Original languageEnglish (US)
Pages (from-to)929-935
Number of pages7
JournalInsect Biochemistry and Molecular Biology
Volume33
Issue number9
DOIs
StatePublished - Sep 1 2003

Keywords

  • Bacillus thuringiensis
  • Binding
  • Cotton
  • Cry toxins
  • Pectinophora gossypiella
  • Resistance

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Insect Science

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