Abstract:

Based on the method of PCR-RFLP and SDS-PAGE,cry genes and their expression products of 72 isolates of Bacillus thuringiensis from different forestry site zones in China were analyzed. Result showed that twenty one strains contained three cry type genes: cry1,cry2 and cry1I, six strains contained both cry1 and cry2 genes, four strains contained both cry1 and cry1I type genes, one strain contained cry1 type gene, four strains contained cry2 type gene. 36 strains did not contain ten cry type genes. Most cry1 genes encoded 130 kDa protein toxic to Lepidopteran pest, and most cry2 genes encoded 60 kDa protein.The isolates containing cry1Aa,cry1Ac and cry2 type genes were highly toxic to Helicoverpa armigera larvae, isolates containing one or no cry gene had low or no toxicity activity to pests.

Key words: Bacillus thuringiensis, ICPs, cry gene, PCR-RFLP, SDS-PAGE, Bioassay