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United States Department of Agriculture

Agricultural Research Service

Research Project: PEST BIOLOGY, ECOLOGY, AND INTEGRATED PEST MANAGEMENT FOR SUSTAINABLE AGRICULTURE

Location: North Central Agricultural Research Laboratory

Title: Isolation of transcripts from Diabrotica virgifera virgifera LeConte responsive to the Bacillus thuringiensis toxin Cry3Bb1

Authors
item Sayed, Abu -
item Wiechman, Barry -
item Struewing, Ian -
item Smith, Mark -
item FRENCH, BRYAN
item NIELSON, CHAD
item Bagley, Mark -

Submitted to: Insect Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 4, 2010
Publication Date: May 5, 2010
Citation: Sayed, A., Wiechman, B., Struewing, I., Smith, M., French, B.W., Nielson, C.N., Bagley, M. 2010. Isolation of Transcripts from Diabrotica Virgifera Virgifera LeConte Responsive to the Bacillus Thuringiensis Toxin Cry3Bb1. Insect Molecular Biology. 19(3):381-389.

Interpretive Summary: Plant incorporated proteins derived from the common soil bacteria, Bacillus thuringiensis (Bt) have been widely used as a method of insect pest management for several decades. Since 2003, a transgenic corn expressing a Cry3Bb1 protein toxin has been successfully used for protection against corn rootworm larvae. Wide spread resistance to Bt by corn rootworms could have significant economic and ecological costs. To help understand the mechanisms of resistance, we identified 19 unique gene transcripts from western corn rootworm that respond to the toxic protein using subtraction hybridization and quantitative RT-PCR. Identification of many of these genes indicated that metabolic and developmental functions are altered in insects reared on Bt diet. Analysis of open reading frames for three highly modulated transcripts resulted in the isolation of three novel genes coding for (i) a member of the cystein-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins (CAP) superfamily, (ii) a glutamine-rich membrane protein gene and (iii) a nondescript 132 amino acid protein. Alternative expression patterns of Cry3Bb1-responsive genes in a population of western corn rootworm that is tolerant to transgenic Cry3Bb1 corn suggests that resistance renders insects capable of bypassing or overcoming Bt-targeted transcriptional disruption.

Technical Abstract: Crystal (Cry) proteins derived from Bacillus thuringiensis (Bt) have been widely used as a method of insect pest management for several decades. In recent years, a transgenic corn expressing the Cry3Bb1 toxin has been successfully used for protection against corn rootworm larvae (Genus Diabrotica). The biological action of the Bt toxin in corn rootworms has not yet been clearly defined. Because development of resistance to Bt by corn rootworms will have huge economic and ecological costs, insight into larval response to Bt toxin is highly desirable. We identified 19 unique transcripts from western corn rootworm (D. virgifera virgifera ) that are responsive to transgenic Cry3Bb1 by subtraction hybridization and quantitative RT-PCR. Putative identification of many of these genes indicated that metabolic and developmental functions are altered in insects reared on Bt diet. Analysis of open reading frames for three highly modulated transcripts resulted in the isolation of three novel genes coding for (i) a member of the cystein-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins (CAP) superfamily, (ii) a glutamine-rich membrane protein gene and (iii) a nondescript 132 amino acid protein. Alternative expression patterns of Cry3Bb1-responsive genes in a population of western corn rootworm that is tolerant to transgenic Cry3Bb1 corn suggests that resistance renders insects capable of bypassing or overcoming Bt-targeted transcriptional disruption.

Last Modified: 9/10/2014