Expression of nitrous oxide reductase from Pseudomonas stutzeri in transgenic tobacco roots using the root-specific rolD promoter from Agrobacterium rhizogenes

Authors

  • Shen Wan,

    1. Department of Biochemistry, Microbiology and Immunology, Center for Research on Environmental Microbiology – CREM, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
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  • Amanda M. Johnson,

    1. Department of Biochemistry, Microbiology and Immunology, Center for Research on Environmental Microbiology – CREM, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
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  • Illimar Altosaar

    1. Department of Biochemistry, Microbiology and Immunology, Center for Research on Environmental Microbiology – CREM, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada
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  • Funded by the NSERC and its industrial and governmental partners through the Green Crop Network.

Illimar Altosaar, Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, Ontario, K1H 8M5, Canada. Tel: +1 613 562–5800 ext. 6374; Fax: +1 613 562–5452; E-mail: altosaar@uottawa.ca

Abstract

The nitrous oxide (N2O) reduction pathway from a soil bacterium, Pseudomonas stutzeri, was engineered in plants to reduce N2O emissions. As a proof of principle, transgenic plants expressing nitrous oxide reductase (N2OR) from P. stutzeri, encoded by the nosZ gene, and other transgenic plants expressing N2OR along with the more complete operon from P. stutzeri, encoded by nosFLZDY, were generated. Gene constructs were engineered under the control of a root-specific promoter and with a secretion signal peptide. Expression and rhizosecretion of the transgene protein were achieved, and N2OR from transgenic Nicotiana tabacum proved functional using the methyl viologen assay. Transgenic plant line 1.10 showed the highest specific activity of 16.7 µmol N2O reduced min−1 g−1 root protein. Another event, plant line 1.9, also demonstrated high specific activity of N2OR, 13.2 µmol N2O reduced min−1 g−1 root protein. The availability now of these transgenic seed stocks may enable canopy studies in field test plots to monitor whole rhizosphere N flux. By incorporating one bacterial gene into genetically modified organism (GMO) crops (e.g., cotton, corn, and soybean) in this way, it may be possible to reduce the atmospheric concentration of N2O that has continued to increase linearly (about 0.26% year−1) over the past half-century.

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