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ARS Home » Pacific West Area » Maricopa, Arizona » U.S. Arid Land Agricultural Research Center » Pest Management and Biocontrol Research » Research » Publications at this Location » Publication #373085

Research Project: Ecologically Based Pest Management in Western Crops Such as Cotton

Location: Pest Management and Biocontrol Research

Title: Shared and independent genetic basis of resistance to Bt toxin cry2ab in two strains of pink bollworm

Author
item Fabrick, Jeffrey
item Leroy, Dannialle
item UNNITHAN, GOPALAN - University Of Arizona
item YELICH, ALEX - University Of Arizona
item CARRIERE, YVES - University Of Arizona
item LI, XIANCHUN - University Of Arizona
item TABASHNIK, BRUCE - University Of Arizona

Submitted to: Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/22/2020
Publication Date: 5/14/2020
Citation: Fabrick, J.A., LeRoy, D.M., Unnithan, G.C., Yelich, A.J., Carriere, Y., Li, X., Tabashnik, B.E. 2020. Shared and independent genetic basis of resistance to Bt toxin cry2ab in two strains of pink bollworm. Scientific Reports. 10. https://doi.org/10.1038/s41598-020-64811-w.
DOI: https://doi.org/10.1038/s41598-020-64811-w

Interpretive Summary: Pest resistance threatens the benefits of crops genetically engineered to produce insecticidal proteins from the bacterium, Bacillus thuringiensis (Bt). The pink bollworm is a global pest of cotton and some field populations in India are resistant to both Bt toxins currently produced by transgenic cotton. Previous results show that mutations disrupting the PgABCA2 gene are associated with pink bollworm resistance to Bt toxin Cry2Ab in both field-selected populations from India and in a lab-selected strain from the United States. Here, ARS scientists at Maricopa, AZ and collaborators show that a second independently derived, lab-selected Cry2Ab-resistant pink bollworm strain from the United States harbors mutations that disrupt PgABCA2 and possess at least one additional mechanism of resistance to Cry2Ab that does not affect PgABCA2. These results indicate that mutations disrupting PgABCA2 are the primary, but not the only, mechanism of resistance to Cry2Ab in pink bollworm. This new knowledge about the genetic basis of Bt resistance is useful for designing improved strategies to monitor and manage pest resistance to transgenic crops.

Technical Abstract: Evolution of pest resistance threatens the benefits of crops genetically engineered to produce insecticidal proteins from Bacillus thuringiensis (Bt). Field populations of the pink bollworm (Pectinophora gossypiella), a global pest of cotton, have evolved practical resistance to Bt toxin Cry2Ab produced by transgenic cotton in India, but not in the United States. Previous results show that recessive mutations disrupting an autosomal ATP-binding cassette gene (PgABCA2) are associated with pink bollworm resistance to Cry2Ab in field-selected populations from India and in one lab-selected strain from the United States (Bt4-R2). Here we discovered that an independently derived, lab-selected Cry2Ab-resistant pink bollworm strain from the United States (BX-R) also harbors mutations that disrupt PgABCA2. Premature stop codons introduced by mis-splicing of PgABCA2 pre-mRNA were prevalent in field-selected larvae from India and in both lab-selected strains. The most common mutation in field-selected larvae from India was also detected in both lab-selected strains. Results from interstrain crosses indicate BX-R has at least one additional mechanism of resistance to Cry2Ab that does not involve PgABCA2 and is not completely recessive or autosomal. We conclude that recessive mutations disrupting PgABCA2 are the primary, but not the only, mechanism of resistance to Cry2Ab in pink bollworm.