The crystal proteins, or 5-endotoxins, of Bacillus thuringiensis are
specifically lethal to Lepidopteran insects. We utilized a truncated and
modified portion of a cloned crystal protein gene to construct a chimeric
gene capable of expression in plant cells. Using an Agrobacterium
tumefaciens binary vector system, we then transferred the chimeric toxin
gene into tobacco (Nicotiana tabacum cv Havana 425) cells and regenerated
recombinant plants. One to several copies per cell of the toxin
gene are routinely present in the recombinant plants. Hybridization
experiments demonstrated that these plants had a new RNA species of
the size expected for the truncated toxin mRNA, and a polypeptide
having the mobility expected for the truncated toxin was detected by
immunoblotting. Significant variation was found in the levels of toxinspecific
RNA expression between different recombinants, but the levels
of hybridizing RNA in transformants correlated with the level of toxicity
demonstrated against Manduca sexta (tobacco hornworm), and other
Lepidopteran insects. The recombinant genes were transmitted to progeny
and resistance to insects was maintained, thus demonstrating that the
introduction of toxin genes into plants may be a practical method of
providing protection against certain insect pests.
The crystal proteins, or 5-endotoxins, of Bacillus thuringiensis arespecifically lethal to Lepidopteran insects. We utilized a truncated andmodified portion of a cloned crystal protein gene to construct a chimericgene capable of expression in plant cells. Using an Agrobacteriumtumefaciens binary vector system, we then transferred the chimeric toxingene into tobacco (Nicotiana tabacum cv Havana 425) cells and regeneratedrecombinant plants. One to several copies per cell of the toxingene are routinely present in the recombinant plants. Hybridizationexperiments demonstrated that these plants had a new RNA species ofthe size expected for the truncated toxin mRNA, and a polypeptidehaving the mobility expected for the truncated toxin was detected byimmunoblotting. Significant variation was found in the levels of toxinspecificRNA expression between different recombinants, but the levelsof hybridizing RNA in transformants correlated with the level of toxicitydemonstrated against Manduca sexta (tobacco hornworm), and otherLepidopteran insects. The recombinant genes were transmitted to progenyand resistance to insects was maintained, thus demonstrating that theintroduction of toxin genes into plants may be a practical method ofproviding protection against certain insect pests.
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