Insect resistance in transgenic plants expressing Bacillus thuringiensis toxin gens

Abstract

A crystal protein gene (ht2) has been cioned from plasmid DNA of Bacllus thuringiensis (B.t.) Lerliner 1715 and directs the synthesis of a 130 kd protein (Bt2) in E. ccli which is toxic to iarvae of P(cris brasciccc and Manduca sa.cta. Treatment of the Bt2 prote.t. with trypsin or chymotrypsin yields a 60 kd protease resistont fragment which is fuily toxic tards insect iarvae " in vivo" and nsect celi lines in vitro". The minimai portion of the 3t2 proein required for toxicity has been rnapped by deletion analysis and coincides with the 60 kd protease resistant Bt2.-fraqment. Tobacco piant celis have been transformed with chiineric toxin genes uing a Ti plasmid vector. Transformed plarits express a functionai toxin and exhibit resistance against insect larvas. iNTRODUCTION Bacilius rniencic (3. . ) is a gram positivebacteriun which produces ondogenous crystais upon sporulation. The crys tais are composed of protein and are specificaliy toxic against Recebido em 03/09/87