Crystal protein and plasmid profile of Bacillus thuringiensis toxic to rice striped stem borer, Chilo suppressalis
1992
Padua, L.E. | Alcantara, E.P. (Philippines Univ., Los Banos, College, Laguna (Philippines). National Inst. of Biotechnology and Applied Microbiology)
A collection of 143 isolates of Bacillus thuringiensis was screened for insecticidal activity against the rice striped stemborer, Chilo suppressalis. B. thuringiensis subsp. Kurstaki and subsp. aizawai were highly toxic to 7-day old larvae. Electrophoretic analysis of the crystal protein revealed two major subunits of 135 and 66 kDa molecular weight. However, the 66 kDa subunits were produced in varying amounts among isolates of B. thuringiensis subsp. kurstaki. B. thuringiensis subsp. kurstaki (HD-1 and LEP-37) produced high amounts of the 66 kDa polypeptide which was low in other kurstaki isolates (LEP-20, 5-9, 235-5 and PG-02). B. thuringiensis subsp. aizawai (LEP-70, 77A and 81) produced only one major polypeptide of 135 kDa molecular weight. Extraction by alkaline lysis showed a complex array of plasmid DNA among isolates. A common feature was the presence of large plasmids with masses greater than 25 MDa. Plasmid masses ranged from 5.2 to about 120 MDa
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