Proteomic analysis of resistance to diverse Cry toxins from Bacillus thuringiensis in strains of Heliothis virescens

Heliothine larvae are among the most commercially relevant pests of several crops worldwide, and are targeted by transgenic crops expressing Cry toxins from Bacillus thuringiensis (Bt). New varieties of these Bt crops expressing multiple Cry toxins are being commercialized for increased activity and to delay the evolution of resistance to Bt crops. However, some laboratory-selected strains of Heliothis virescens display cross-resistance to diverse Cry toxins, suggesting that these insects may develop resistance to Bt crops expressing diverse Cry toxins. In an effort to understand the mechanisms involved in cross-resistance to Cry toxins, we performed a comparative proteomic analysis of the response to Cry intoxication in susceptible (YDK) and Bt-resistant (CXC and KCB) strains of H. virescens. After detection of proteins differentially expressed in response to toxin challenge using differential in-gel electrophoresis (DIGE), we identified these proteins using mass spectrometry. Results are compared to previous genomic and proteomic analyses of H. virescens midgut tissue and cell secretions and potential resistance mechanisms are discussed.