Pest Management Science (2020) 76, 67-74

Jeffrey A. Fabrick, Lolita G. Mathew, Dannialle M. LeRoy, J. Joe Hull, Gopalan C. Unnithan, Alex J. Yelich, Yves Carrière, Xianchun Li and Bruce E. Tabashnik (2020)
Reduced cadherin expression associated with resistance to Bt toxin Cry1Ac in pink bollworm
Pest Management Science 76 (1), 67-74
Abstract:
BACKGROUND
Better understanding of the molecular basis of resistance is needed to improve management of pest resistance to transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt). Here we analyzed resistance of the pink bollworm (Pectinophora gossypiella) to Bt toxin Cry1Ac, which is used widely in transgenic Bt cotton. Field-evolved practical resistance of pink bollworm to Cry1Ac is widespread in India, but not in China or the United States. Previous work with laboratory- and field-selected pink bollworm indicated that resistance to Cry1Ac is caused by changes in the amino acid sequence of a midgut cadherin protein (PgCad1) that binds Cry1Ac in susceptible larvae.
RESULTS
Relative to a susceptible strain, the laboratory-selected APHIS-R strain had 530-fold resistance to Cry1Ac with autosomal recessive inheritance. Unlike previous results, resistance in this strain was not consistently associated with insertions or deletions in the expected amino acid sequence of PgCad1. However, this resistance was associated with 79- to 190-fold reduced transcription of the PgCad1 gene and markedly lower abundance of PgCad1 protein.
CONCLUSION
The ability of pink bollworm and other major pests to evolve resistance to Bt toxins via both qualitative and quantitative changes in receptor proteins demonstrates their remarkable adaptability and presents challenges for monitoring and managing resistance to Bt crops.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Yves Carriere, Bruce E. Tabashnik, Jeff A. Fabrick

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pectinophora gossypiella	Cotton (Gossypium)
Bacillus thuringiensis genes in crops (entomopathogen)	Pectinophora gossypiella	Cotton (Gossypium)
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Pectinophora gossypiella	Cotton (Gossypium)