Two delta-endotoxin genes, cry9Da and a novel related gene, commonly occurring in lepidoptera-specific Bacillus thuringiensis Japanese isolates that produce spherical parasporal inclusions

Six Lepidoptera-specific Bacillus thuringiensis isolates, which belong to t he four H serovars (sotto, fukuokaensis, canadensis, and galleriae) and pro duce spherical parasporal inclusions, were examined for assignment of the c lasses of the delta -endotoxin genes. Gene analysis was conducted by PCR te chnique with primers designed to probe the genes cry9Ca and cry9Da. The dat a revealed that the delta -endotoxin of a serovar canadensis isolate is enc oded by the gene cry9Da, while those of the five other strains are encoded by an undescribed delta -endotoxin gene. DNA fragments from five strains ha d an identical 1917-bp nucleotide sequence, covering the four conserved reg ions and a partial sequence of the block 5 region. The deduced amino acid s equence exhibited a 70.6% homology to that of the corresponding region of t he Cry9Ea delta -endotoxin protein which is active on the order Lepidoptera , and a 63.1% homology to the Cry9Ca protein highly toxic to the noctuid le pidopterans. The results showed that Japanese isolates of B. thuringiensis producing spherical parasporal inclusions with Lepidoptera-specific activit y are categorized into two groups: one produces the class Cry9Da protein an d the other a novel delta -endotoxin allied to the class Cry9. It also appe ared that heterogeneous multiple H serovars are involved in each group.