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Applied and Environmental Microbiology, April 2002, p. 1509-1515, Vol. 68, No. 4
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.4.1509-1515.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.

Role of Bacillus thuringiensis Cry1 {delta} Endotoxin Binding in Determining Potency during Lepidopteran Larval Development

Androulla Gilliland,* Catherine E. Chambers, Eileen J. Bone, and David J. Ellar

Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, United Kingdom

Received 15 October 2001/ Accepted 10 January 2002

Five economically important crop pests, Manduca sexta, Pieris brassicae, Mamestra brassicae, Spodoptera exigua, and Agrotis ipsilon, were tested at two stages of larval development for susceptibility to Bacillus thuringiensis toxins Cry1Ac, Cry1Ca, Cry1J, and Cry1Ba. Bioassay results for M. sexta showed that resistance to all four Cry toxins increased from the neonate stage to the third-instar stage; the increase in resistance was most dramatic for Cry1Ac, the potency of which decreased 37-fold. More subtle increases in resistance during larval development were seen in M. brassicae for Cry1Ca and in P. brassicae for Cry1Ac and Cry1J. By contrast, the sensitivity of S. exigua did not change during development. At both larval stages, A. ipsilon was resistant to all four toxins. Because aminopeptidase N (APN) is a putative Cry1 toxin binding protein, APN activity was measured in neonate and third-instar brush border membrane vesicles (BBMV). With the exception of S. exigua, APN activity was found to be significantly lower in neonates than in third-instar larvae and thus inversely correlated with increased resistance during larval development. The binding characteristics of iodinated Cry1 toxins were determined for neonate and third-instar BBMV. In M. sexta, the increased resistance to Cry1Ac and Cry1Ba during larval development was positively correlated with fewer binding sites in third-instar BBMV than in neonate BBMV. The other species-instar-toxin combinations did not reveal positive correlations between potency and binding characteristics. The correlation between binding and potency was inconsistent for the species-instar-toxin combinations used in this study, reaffirming the complex mode of action of Cry1 toxins.

* Corresponding author. Present address: Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, United Kingdom. Phone: 44 (0) 1223 330215 or 44 (0) 1223 330224. Fax: 44 (0) 1223 333900. E-mail: ak10017{at}cus.cam.ac.uk.

Applied and Environmental Microbiology, April 2002, p. 1509-1515, Vol. 68, No. 4
0099-2240/02/$04.00+0     DOI: 10.1128/AEM.68.4.1509-1515.2002
Copyright © 2002, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Pigott, C. R., King, M. S., Ellar, D. J. (2008). Investigating the Properties of Bacillus thuringiensis Cry Proteins with Novel Loop Replacements Created Using Combinatorial Molecular Biology. Appl. Environ. Microbiol. 74: 3497-3511 [Abstract] [Full Text]  
  • Fortier, M., Vachon, V., Frutos, R., Schwartz, J.-L., Laprade, R. (2007). Effect of Insect Larval Midgut Proteases on the Activity of Bacillus thuringiensis Cry Toxins. Appl. Environ. Microbiol. 73: 6208-6213 [Abstract] [Full Text]  
  • Vilchez, S., Jacoby, J., Ellar, D. J. (2004). Display of Biologically Functional Insecticidal Toxin on the Surface of {lambda} Phage. Appl. Environ. Microbiol. 70: 6587-6594 [Abstract] [Full Text]  


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