MP9 Metals and Bioaccumulation
Monday, 14 November 2005: 8:00 AM - 5:30 PM in Exhibit Hall

(FAR-1117-815757) The use of transgenic canola (Brassica napus) and plant growth-promoting bacteria for the phytoremediation of a nickel contaminated site.

Farwell, AJ¹, Vesely, S¹, Rodriguez, H², Nero, V¹, Dixon, DG¹, Glick, BR¹, ¹ University of Waterloo, Waterloo, Ontario, Canada² Cuban Research Institute on Sugarcane By-Products

ABSTRACT- Laboratory studies have indicated the potential for use of canola (Brassica napus L., cv. Westar) with novel traits and the plant growth-promoting bacterium (PGPB) (Pseudomonas putida UW4) as a method to remediate nickel-contaminated soil. Transgenic canola expressing the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase under the transcriptional control of the rolD promoter and the bacterium P. putida UW4 were tested for the ability to remediate nickel-contaminated soil in the field. This enzyme activity can degrade ACC that is produced by plant roots in response to a variety of stresses, including the presence of nickel, and thereby increase plant growth and provide greater quantities of above ground biomass for harvest in remediation efforts. To determine the efficacy of transgenic canola and/or PGPB as a method for nickel remediation, field trials were conducted in southern Ontario at a site contaminated with elevated levels of nickel ( 6500 g/g). In the first field trial (June 9 - July 13, 2004) non-transgenic canola and transgenic canola with two copies of the ACC deaminase gene under the control of rolD promoter produced similar shoot biomass compared to multi-copy and single copy transgenic canola with the rolD promoter. The non-transgenic and double copy transgenic canola showed similar changes in shoot biomass (<1.0 g – 8.0 g) with increasing Ni content in the shoots (<80 g/g shoot dry weight). As a result of partial flooding, the evaluation of P. putida UW4 for plant growth promotion in the second field trial (August 31-October 5, 2004) was limited to plants from low Ni contaminated soil (<28 g/g shoot dry weight). The available data showed significant increases in growth for both non-transgenic and double copy transgenic canola inoculated with P. putida UW4. Additional field trials (2005) will be conducted to further evaluate the use of transgenic canola and/or PGPB in metal remediation.

Key words: Metal phytoremediation, Nickel, Transgenic canola, Plant growth-promoting bacteria