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Engineering herbicide metabolism in tobacco and Arabidopsis with CYP76B1, a cytochrome P450 enzyme from Jerusalem artichoke

Didierjean, L., Gondet, L., Perkins, R., Lau, S.M.C., Schaller, H., O'Keefe, D.P., Werck-Reichhart, D.
Plant physiology 2002 v.130 no.1 pp. 179-189
Nicotiana tabacum, tobacco, transgenic plants, plant development, Helianthus tuberosus, Jerusalem artichokes, plant proteins, cytochrome P-450, oxidoreductases, complementary DNA, recombinant proteins, gene expression, enzyme activity, genetic transformation, phenylurea herbicides, isoproturon, chlorotoluron, metabolism, herbicide resistance, chemical structure, biochemical pathways, Saccharomyces cerevisiae, plant morphology, amino acid sequences, nucleotide sequences, chemical constituents of plants
The Jerusalem artichoke (Helianthus tuberosus) xenobiotic inducible cytochrome P450, CYP76B1, catalyzes rapid oxidative dealkylation of various phenylurea herbicides to yield nonphytotoxic metabolites. We have found that increased herbicide metabolism and tolerance can be achieved by ectopic constitutive expression of CYP76B1 in tobacco (Nicotiana tabacum) and Arabidopsis. Transformation with CYP76B1 conferred on tobacco and Arabidopsis a 20-fold increase in tolerance to linuron, a compound detoxified by a single dealkylation, and a 10-fold increase in tolerance to isoproturon or chlortoluron, which need successive catalytic steps for detoxification. Two constructs for expression of translational fusions of CYP76B1 with P450 reductase were prepared to test if they would yield even greater herbicide tolerance. Plants expressing these constructs had lower herbicide tolerance than CYP76B1 alone, which is apparently a consequence of reduced stability of the fusion proteins. In all cases, increased herbicide tolerance results from more extensive metabolism, as demonstrated with exogenously fed phenylurea. Beside increased herbicide tolerance, expression of CYP76B1 has no other visible phenotype in the transgenic plants. Our data indicate that CYP76B1 can function as a selectable marker for plant transformation, allowing efficient selection in vitro and in soil-grown plants. Plants expressing CYP76B1 may also be a potential tool for phytoremediation of contaminated sites.