Preliminary comparing the toxicities of the hybrid cry1Acs fused with different heterogenous genes provided guidance for the fusion expression of Cry proteins.

In order to provide guidance for selecting suitable heterogenous gene that can efficiently enhance toxicity or broaden insecticidal spectrum of Cry1Ac through fusion expression, two hybrid cry1Acs fused with chitinase-encoding gene tchiB and neurotoxin gene hwtx-1 respectively were constructed and their toxicities were compared. A Bacillus thuringiensis strain harboring the cry1Ac gene in vector pHT315 was used as control. Bioassay revealed that LC(50) (after 72 h) of Cry1Ac protoxin was 41.01 μg mL(-1), while the hybrid cry1Acs fused with tchiB and hwtx-1 were 4.89 and 23.14 μg mL(-1), which were 8.23- and 1.77-fold higher than Cry1Ac protoxin in terms of relative toxicity respectively. Both fusion crystals had a higher toxicity than the original Cry1Ac protein and the toxicity of hybrid cry1Acs fused with hwtx-1 experienced a more significant increase than that fused with tchiB.