PNAS Online Early Edition
"An alternative strategy for sustainable pest resistance in genetically enhanced crops"
Luke Mehlo, Daphrose Gahakwa, Pham Trung Nghia, Nguyen Thi Loc, Teresa Capell, John A. Gatehouse, Angharad M. R. Gatehouse, and Paul Christou
Article #02871

ABSTRACT

Researchers report the development of a genetically engineered crop providing long-term resistance against many insect species. The Bt gene, which has already been incorporated into potatoes, cotton, and corn, enables a plant to produce an insecticide. But researchers fear that heavy use of commercial pesticides containing Bt will breed resistant bugs. Paul Christou and colleagues modified the Bt gene to make it more difficult for insects to evolve resistance. The researchers fused the original Bt gene with a gene segment called RB, enabling the Bt toxin bind to more types of molecules in the insects' gut, making it more lethal. Rice and corn plants with this BtRB fusion gene were shown to be more toxic to a wider range of insects than plants with Bt alone. Corn plants producing low levels of BtRB killed 75% of stem borer larvae, compared with 17% in Bt-only plants. Bt-resistant cotton leaf worm was highly susceptible to BtRB plants; 90% of larvae died within 9 days. BtRB was not toxic to all insects, with no effect on the cereal aphid Rhopalosiphum padi. The authors say further tests are necessary to make certain BtRB crops are not toxic or allergenic in humans.

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