Toxin engineering for enhanced toxicity against the soybean aphid, Aphis glycines, Matsumura

Current aphid management strategies are heavily reliant on the use of potentially environmentally damaging chemical insecticides.  Toxins derived from Bacillus thuringiensis provide an alternative to the use of chemical insecticides, but are limited in their use against aphids and other hemipteran pests due to low levels of toxicity.  Previous work in our lab has demonstrated that the addition of a short peptide sequence to the Bt toxin Cyt2Aa, resulted in an increase in relative binding to brush border membrane vesicles (BBMV) derived from the pea aphid (Acyrthosiphon pisum) and the green peach aphid (Myzus persicae).  A corresponding increase in toxicity of Cyt2Aa against both the green peach aphid and the pea aphid was observed.  A similar approach has been applied to the modification of Cry4Aa for enhanced toxicity against the soybean aphid (Aphis glycines).  Current work is focused on evaluating binding of several soybean aphid gut binding peptides first identified in vivo by screening a phage display library for peptides that bind the soybean aphid gut, for possible incorporation into Cry4Aa.  Experimental results and plans will be presented.