Genetic basis of tobacco budworm resistance to an engineered Pseudomonas fluorescens expressing the δ-endotoxin of Bacillus thuringiensis kurstaki

Inheritance of tobacco budworm ( Heliothis virescens) resistance to a recombinant Pseudomonas expressing the 130-kDa δ-endotoxin protein of Bacillus thuringiensis strain HD-1 was studied. The tobacco budworm line used was 12-fold more resistant to the endotoxin (LC 50) than the susceptible strain. Resistance was autosomally inherited, incompletely dominant, and controlled by several genetic factors. Genetic control of resistance was unstable. An unchallenged line with an initial resistance of 69-fold that of the susceptible line declined to 13-fold by generation 5 of nonselection.