Screening Bt Strain Against Anoplophra Glabripennis (Motsch.) And Cloning Its Toxin Gene

Ten Bt strains were selected by insect bioassay based on the results of IPC toxicity aginst larvae of Pyrrhalta aenescens (Fairmaire). Four of them were further test on their activities against larvae of Anoplophra glabripennis(Motsch.) in 2-3 instar. Bt886 gave the most effective inhibition to the growth of the larvae among the four Bt strains.A 819bp DNA fragment was amplified from the above strains by designed primers based on the CrySAa gene sequence, and further sequenced using the same set of primers. The sequence was identical to the cry3Aa except one nucleotide acid substitution.Southern hybridization showed the above gene was located on the plasmid from Bt886. In addition, this fragment appeared only one copy in the plasmid DNA.A pair of specific primers was used to amplify the full-length cry3Aa gene. The size of PCR product was about 2.0kb as expected and further cloned. The partial sequence obtained suggested that the gene belonged to Cry3Aa gene family. Further characterization of the gene is under going.