A Study On The Effects Of Bacillus Thuringiensis Crystal Protein Cry6Aa2Against Caenorhabditis Elegans By Proteomics Technology

Bacillus thuringiensis (Bt) is a gram-positive bacterium which produces a variety of insecticidal toxins. Parasporal crystal protein produced by Bt during the sporulation phase of Bt growth cycle exhibits high toxicity to many insects. Parasporal crystal protein has been extensively studied and used in biocontrol for insects and nematodes. Cry6Aa2parasporal crystal protein is produced by nematicidal Bt, has a variety of nematicidal properties. The previous studies reported that Cry6Aa2was virulent to root-knot nematode (RNK) and Caenorhabditis elegans. Cry6Aa2is not only lethal to RNK and C. elegans, but also significantly inhibit spawning, growth, and movement ability of C. elegans. Meanwhile, when attacked by Cry6Aa2toxin, C. elegans uses behavioral strategies to advoid intoxication, including physical evasion and reduction of uptake frequency. However, nematicidal properties of Cry6Aa2to RNK Meloidodynidae incognita and the defense mechanism of C. elegans against Cry6Aa2are not clear.Firstly, this study tested the effects of purified Cry6Aa2against the M. incognita on mortality, egg hatch, juvenile motility in vitro and infection to host plant roots. Cry6Aa2adversely affected survival, egg hatch, juvenile mobility and infection ability of M. incognita. All these results suggested that Cry6Aa2is able to interrupt life cycle of M. incognita, and might be a promising microorganism for biocontrol of RNK.Secondly, in this study, the process of Cry6Aa2how to effect C. elegans and the defense mechanism of C. elegans against Cry6Aa2threat were studied by proteomics technology. We achieved ten differential proteins between the treatment C. elegans proteomic and the control by proteomics technology. Further, transcription level of the ten differential proteins and other three proteins were detected by qRT-PCR, and the accordance of differential proteins between protein expression level and transcription level was studied. The research about three mutant C. elegans verified effects of three kinds of differential proteins in the defense mechanism of C. elegans against Cry6Aa2. These results showed that various heat shock proteins (HSP-12.2, HSP-6, HSP-25) are up-regulation to repair damage caused by Cry6Aa2, DIM-1and a number of energy pathways play important roles in the process of C. elegans defense Cry6Aa2intoxication, such as citric acid cycle, electron transport. Meanwhile, Cry6Aa2toxin can stimulate up-regulation of DAF-2and down-regulation of DAF-16, may be shorten the lifespan of C. elegan.In conclusion, Cry6Aa2have a variety of nematicidal properties to M. incognita, and there is a need for further studies to examine the control efficiency of Cry6Aa2in pot experiment and the field trial. Meanwhile, we preliminary identified interaction between Cry6Aa2and C.elegans, but further studies is need toidentify:(1) what functions do these energy metabolism enzymes make in defense process of C. elegans against Cry6Aa2;(2) what roles do DIM-1play in defense process of C. elegans against Cry6Aa2;(3) how Cry6Aa2to affect lifespan of C. elegans.