Expression of Cry3Bb1 in transgenic corn MON88017

Area of Science:

• Agricultural Science
• Molecular Biology
• Entomology

Background:

• Assessing the ecological impact of Bt crops requires accurate quantification of expressed insecticidal proteins.
• Transgenic expression of Bacillus thuringiensis (Bt) proteins, like Cry3Bb1, in crops necessitates reliable methods for content determination.

Purpose of the Study:

• To optimize and validate a quantitative double antibody sandwich-enzyme-linked immunosorbent assay (DAS-ELISA) for measuring Cry3Bb1 protein in Bt corn.
• To determine Cry3Bb1 content in various tissues of Bt corn MON88017 across different developmental stages and growing seasons.

Main Methods:

• Adaptation and validation of a commercial qualitative PathoScreen DAS-ELISA kit for quantitative Cry3Bb1 detection.
• Field trials in Germany (2005-2007) to quantify Cry3Bb1 in Bt corn MON88017 tissues at four developmental stages.
• Measurements were performed using both dry weight (dw) and fresh weight (fw) for Cry3Bb1 content.

Main Results:

• The optimized DAS-ELISA method demonstrated an average accuracy of 84-109%.
• Cry3Bb1 expression was highest in young leaves and lowest in pollen, with significant seasonal decline observed in root tissues (from 130 to 40 microg/g dw).
• An estimated 905 g of Cry3Bb1 can be produced per hectare of Bt corn MON88017, based on total biomass.

Conclusions:

• A validated quantitative DAS-ELISA method provides accurate Cry3Bb1 measurements in Bt corn.
• Understanding Cry3Bb1 distribution and dynamics in plants is essential for ecological risk assessment of Bt crops.
• Seasonal decline in Cry3Bb1 content highlights the importance of considering plant development in exposure assessments.