A dominant gene which, when inserted into a plant’s genome, imparts resistance to glufosinate-ammonium containing herbicides. Because the glufosinate-ammonium herbicides act via inhibition of glutamine synthetase (an enzyme that catalyzes the synthesis of glutamine), this inhibition of enzyme kills plants (e.g., weeds). That is because glutamine is crucial for plants to synthesize critically needed amino acids. The PAT gene is often used by genetic engineers as a marker gene.