<p style="text-align: justify;">Maize line DLL25 (synonym B16) was 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>bar</i> gene, conferring tolerance to glufosinate ammonium, was isolated from the common aerobic soil actinomycete, <i>Streptomyces hygroscopicus</i>, and encodes the enzyme phosphinothricin-N-acetyltransferase (PAT). The PAT enzyme occurs naturally in the soil and acetyltransferases are ubiquitous in nature.</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 field tolerance to phosphinothricin containing herbicides. Glufosinate ammounium acts by inhibiting the plant enzyme glutamine synthetase, a key enzyme that detoxifies ammonia by incorporating it into glutamine. Inhibition of this enzyme leads to an accumulation of ammonia in the plant tissues, which kills the plant within hours of application. PAT catalyses the acetylation of phosphinothricin detoxifying it into an inactive compound. The modified corn permits farmers to use phosphinothricin-containing herbicides for weed control in the cultivation of corn.</p>
