Identification of novel cry-type genes from Bacillus thuringiensis strains on the basis of restriction fragment length polymorphism of the PCR-amplified DNA

Two pairs of universal oligonucleotide primers were designed to probe the most conserved regions of all known cryI-type gene sequences so that the amplified PCR fragments of the DNA template from Bacillus thuringiensis strains may contain all possible cryI-type gene sequences, The restriction fragment length polymorphism (RFLP) patterns of the PCR-amplified fragments revealed that 14 distinct cry-type genes have been identified from 20 B. thuringiensis strains, Those cry-type genes included cryIA(a), cryIA(a)dagger, cryIA(b), cryIA(b)dagger, cryIA(c), cryIB dagger, cryIC, cryIC dagger, cryIC(b), cryID, cryIE, cryIF, cryIF dagger, and cryIII dagger (a dagger at the end of a gene designation indicates a novel cry-type gene determined by restriction mapping or DNA sequences), Among them, the sequences of cryIA(a)dagger, cryIA(b)dagger, cryIB dagger, cryIC dagger, cryIF dagger, and cryIII dagger were found to be different from the corresponding published cry gene sequences, Interestingly, five cry-type genes [cryIA(a)dagger-, cryIB-, cryIC-, cryIC(b)-, and cryIF-type genes] and seven cry-type genes [cryIA(a)dagger-, cryIA(b)dagger-, cryIB dagger-, cryIC dagger-, cryIC(b)-, cryIF-, and cryIII-type genes] have been detected from B, thuringiensis subsp, morrisoni HD-12 and B, thuringiensis subsp, wuhanensis, respectively, Therefore, the PCR-RFLP typing system is a facile method to detect both known and novel cry genes existing in B, thuringiensis strains.