ENGINEERING OF GLUFOSINATE RESISTANCE AND EVALUATION UNDER FIELD CONDITIONS

Glufosinate and bialaphos are non-selective herbicides which act by inhibiting glutamine synthetase. A gene which confers resistance to bialaphos (bar) was isolated from Streptomyces hygroscopicus, the organism which produces bialaphos. The gene was shown to encode a phosphinothricin acetyl transferase. Using Agrobacterium-mediated Ti plasmid transformation methodology, the bar gene has been introduced into and expressed in several plant species. Transgenic tobacco, tomato, potato, poplar, alfalfa, oilseed rape and sugar beet plants show a complete resistance towards the commercial preparations of glufosinate and bialaphos. The strategy thus provides a successful approach to obtain herbicide-resistant plants by introducing a pathway for detoxification of the herbicide. At present, these crops are being evaluated under open field conditions. Results thus far demonstrate a complete resistance to field dose applications, no yield penalties, and confirmed that glufosinate can be applied as a selective post-emergence herbicide on engineered crops.