<!-- Generated by XStandard version 3.0.0.0 on 2012-10-23T14:40:19 -->
<p style="text-align: justify;">The GA21 line of maize (<i>Zea mays</i> L.) was genetically engineered, by particle acceleration (biolistic) transformation, to be tolerant of glyphosate-containing herbicides. The isolated endogenous maize 5-enolpyruvylshikimate-3-phosphate synthase (EPSSP) gene was modified through site-directed mutagenesis, such that its encoded enzyme was insensitive to inactivation by glyphosate, and inserted into the inbred AT maize variety.</p>

<p style="text-align: justify;">Glyphosate specifically binds to and inactivates EPSPS, which is involved in the biosynthesis of the aromatic amino acids tyrosine, phenylalanine and tryptophan. This enzyme is present in all plants, bacteria and fungi, but not in animals, which do not synthesize their own aromatic amino acids. Thus, EPSPS is normally present in food derived from plant and microbial sources. The modified maize line permits farmers to use glyphosate-containing herbicides, such as Roundup herbicide, for weed control in the cultivation of maize.</p>
