<p style="text-align: justify;">Maize lines T14 and T25 were developed through a specific genetic modification to allow the use of glufosinate ammonium, the active ingredient in phosphinothricin herbicides (Basta, Rely, Finale, and Liberty), as a weed control option in maize crops. The <i>pat</i> gene, conferring tolerance to glufosinate ammonium, was cloned from the common aerobic soil actinomycete, <i>Streptomyces viridochromogenes</i>, and encodes the enzyme phosphinothricin-N-acetyltransferase (PAT).</p>

<p style="text-align: justify;">The PAT enzyme was used as a selectable marker enabling identification of transformed plant cells as well as a source of resistance to the herbicide phosphinothricin (also known as glufosinate ammonium). Phosphinothricin containing herbicides, such as glufosinate ammonium, act by inhibiting glutamine synthetase resulting in the accumulation of toxic levels of ammonia that kill the plant within hours of application. The PAT enzyme detoxifies phosphinothricin by acetylation into an inactive compound. The modified corn permits farmers to use phosphinothricin-containing herbicides for weed control in the cultivation of corn.</p>
