CROPS RESISTANT TO OXYNILS - FROM THE LABORATORY TO THE MARKET

Herbicide resistance was one of the first traits introduced to crops b y transgenic methods. The main reason for this was the fact that it is generally controlled by a single gene and that a large body of bioche mical information is available on the mode of action, mechanisms of re sistance and metabolism of herbicide molecules. Oxynil herbicides, suc h as bromoxynil and ioxynil, destroy dicot plants. In order to extend the selectivity of these herbicides to some of the major dicot crops s uch as cotton and oilseed rape, a gene coding for a nitrilase which sp ecifically detoxifies these herbicides was isolated in collaboration w ith Calgene (Davis, CA, USA). The coding region of the gene was linked to regulatory DNA sequences for expression in plants and transferred into various dicotyledonous species, such as tobacco, tomato, cotton, oilseed rape, carrot, potato and eggplant. All plants containing the b acterial nitrilase gained resistance to oxynil herbicides. Field exper iments have already been conducted with cotton, oilseed rape, tobacco and potato. They show the transgenic cultivars behave identically as t he non-transgenic ones and that herbicide resistance at the agronomic level has been achieved. Experiments are in progress for the commercia l development of some of these lines.