<p style="text-align: justify;">Canola (<i>Brassica napus</i>) line T45 (synonym HCN28) was developed using recombinant DNA techniques to allow the use of glufosinate ammonium, the active ingredient in phosphinothricin herbicides such as Basta&reg;, Rely&reg;, Finale&reg;, and Liberty&reg;.</p>

<p style="text-align: justify;">Prior to the novel food safety assessment of T45, Health Canada had approved the glufosinate tolerant canola lines HCN92 (Innovator) and HCN10, both derived form the transformation event Topas 19/2. The primary difference between T45 and Topas 19/2 derived transformants is that the former does not contain an antibiotic resistance marker gene. The phosphinothricin-N-acetyltransferase (<i>pat</i>) gene introduced into T45, which conferred the novel trait of glufosinate herbicide tolerance, was also used as a selectable marker for screening transgenic plants, thereby eliminating the need for an antibiotic resistance marker in the construct.</p>

<p style="text-align: justify;">Glufosinate is a short name for the ammonium salt, glufosinate-ammonium. It is a broad-spectrum contact herbicide and is used to control a wide range of weeds after the crop emerges or for total vegetation control on land not used for cultivation. Glufosinate herbicides are also used to desiccate (dry off) crops before harvest.</p>

<p style="text-align: justify;">Glufosinate is a natural compound isolated from two species of Streptomyces fungi. It inhibits the activity of an enzyme, glutamine synthetase, which is necessary for the production of glutamine and for ammonia detoxification. The application of glufosinate leads to reduced glutamine and increased ammonia levels in the plant tissues. This causes photosynthesis to stop and the plant dies within a few days. Glufosinate also inhibits the same enzyme in animals. Glufosinate ammonium is currently registered in Canada as a non-selective herbicide for both non-crop and crop uses. It is highly biodegradable, has no residual activity, and very low toxicity for humans and wild fauna.</p>
