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Crop Biotech Update

Scientists Modify Bt Toxin to Improve Activation in Pea Aphid Gut

June 8, 2016
Aphids are one of the most destructive insect pests of many agricultural crops. Thus, Iowa State University (ISU) scientist Michael Rausch and partners optimized the Bt toxin to be used against pea aphid (Acyrthosiphon pisum). 

The Bt protein, Cry4Aa toxin, has low aphicidal activity. The ISU researchers introduced cathepsin L and cathepsin B cleavage sites into Cry4Aa for immediate activation in the aphid gut environment. Results showed that the incubation of modified Cry4Aa and aphid proteases in vitro had improved activation in some of the modified constructs compared to non-modified Cry4Aa. Furthermore, aphids fed with diets containing the modified toxin exhibited higher mortality rates. Based on these results, toxin modification can be used to effectively manage aphid populations through transgenic plant resistance.

Read the research paper in Plos One.