<p style="text-align: justify;">LLCotton25 was developed to allow the use of glufosinate ammonium as a weed control option in cotton production.&nbsp; This genetically engineered cotton line expresses a protein, phosphinothricin-acetyl-transferase (PAT) that confers tolerance to the active ingredient L-phosphinothricin in glufosinate ammonium. The expression of PAT is due to the introduction of the <i>bar</i> gene. This gene was isolated from <i>Streptomyces hygroscopius</i>, a gram-positive soil bacterium.<br />
Glufosinate ammonium is a post-emergence, broad-spectrum contact herbicide and plant dessicant.&nbsp; L-Phosphinothricin was first isolated as bialaphos, an antibiotic synthesized during the fermentation of <i>Streptomyces hygroscopicus</i> or <i>S.viridochromogenes.&nbsp; </i>&nbsp;In herbicidal formulations it is a component of glufosinate ammonium, which is chemically synthesized.&nbsp; Glufosinate ammonium is a racemic mixture of L-phosphinothricin, the herbicidal active moiety, and its D-enantiomer.&nbsp; L-Phosphinothricin is structurally similar to glutamate, the substrate of glutamine synthetase (GS), an enzyme that catalyzes the synthesis of glutamine from glutamate and ammonia.&nbsp; L-phosphinothricin inhibits the activity of GS irreversibly by binding to its active sites.&nbsp; The inhibition of GS caused by the application of glufosinate ammonium to plants results in the accumulation of ammonia, the reduction in the levels of glutamine, and the inhibition of photosynthesis, all of which results in the death of the plant.&nbsp; Plants transformed with the <i>bar</i> gene express the enzyme phosphinothricin-acetyl-transferase (PAT) which acetylates L-phosphinothricin into a non- phytotoxic metabolite (N-acetyl-L-glufosinate).</p>

<p style="text-align: justify;">LLCotton25 was developed by introducing the bialaphos resistance (<i>bar</i>) gene into the cotton variety &lsquo;Coker312,&rsquo; using <i>Agrobacterium</i>-mediated plant transformation.&nbsp; The development of LLCotton25 has allowed the use of glufosinate ammonium as an alternative herbicide for weed control in cotton.&nbsp; This may help reduce the incidence of herbicide resistant biotypes by adding an additional class of herbicides in weed management systems.</p>
