Studies on Resources of Cry-type Genes of Bacillus thuringie-nsis from Different Soil of Forest Site Zone in China

cry genes, express protein and bioassay of 72 isolations of Bacillus thuringiensis from different forest site zones(cool temperate zone, temperate zone, warm temperate zone, north subtropical zone, subtropical zone, south subtropical zone, high plateau subtropical zone, tropical zone) in China were analyzed by the methods of PCR RFLP and SDS PAGE. The results showed that 21 strains contained three cry type genes: cry1, cry1 and cry1; 6 strains contained both cry1 and cry1 genes, 4 strains contained both cry1 and cry1I type genes; 1 strain contained cry1 type gene, 4 strains contained cry1 type gene, 36 strains did not contain the ten cry type genes. Most cry1 genes encoded 130 kD protein that is toxic to Lepidopteron pest, and most cry1 gene encoded 60 kD protein. The isolates of containing cry1Aa, cry1Ac and cry1A type genes had higher toxicity to Helicoverpe armigera, Clostera anachoreta, Lymantria dispar, Dendrolimus punctatus larvae, but isolations of containing one or no cry gene had low toxicity to these pests.