COTTON PLANTS TRANSFORMED WITH A BACTERIAL-DEGRADATION GENE ARE PROTECTED FROM ACCIDENTAL SPRAY DRIFT DAMAGE BY THE HERBICIDE 2,4-DICHLOROPHENOXYACETIC ACID

The agronomic performance of broad leaved crop plants such as cotton would be greatly improved if genetically-engineered resistance to broadleaf herbicides could both protect the plants from accidental spray drift damage and allow the suppression of problem broadleaf weeds by chemical means. Following in vitro modification and the addition of plant expression signals, the gene for 2,4-D monooxygenase, a bacterial enzyme that degrades the broadleaf herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), was introduced into cotton plants by Agrobacterium-mediated transformation. First generation homozygous progeny of regenerated transgenic cotton plants carrying this gene exhibited up to a 50-100 fold increase in tolerance to 2,4-D compared with untransformed controls, and glasshouse trials suggest that the genetically-engineered plants would be completely protected from spray drift of 2,4-D, at least up to the normal field application rates commonly used on neighbouring cereal crops.