Interplant signaling and its effects on Bt toxin expression in corn rootworm-targeting transgenic corn

Levels of Bt toxin expression by transgenic plants are an important factor in managing crop loss and insect resistance development.  Expression of Bt toxin by transgenic plants may vary in response to environmental conditions.  Earlier investigations by our team have found that Bt toxin expression in rootworm-targeting corn roots was affected when Bt plants were grown in proximity to non-Bt plants, in comparison to plants grown individually.  Therefore now we further our investigations to determine whether Bt toxin expression is affected by the genotype of neighboring plants (Bt or non-Bt).  We also investigated whether these interactions were mediated by chemical cues emitted via root or aerial tissue.  To accomplish this, we grew corn plants in greenhouse mesocosms and isolated root or aerial tissue to restrict plant-plant interactions via these tissues.  We then performed qRT-PCR on corn root tissue to determine whether Bt toxin expression levels were affected by tissue signaling restriction.  Results from these experiments will be presented and potential implications for efficacy of Bt-expressing transgenic plants will be discussed.