<p style="text-align: justify;">The BT11 corn line was created through direct DNA transformation of plant protoplasts from the inbred maize line H8540 and regeneration on selective medium. A single plasmid, designated pZO1502, was used in the transformation event and contained a truncated synthetic <i>cry1Ab</i> gene encoding Cry1Ab endotoxin and a synthetic <i>pat</i> gene (to allow transformant selection on glufosinate ammonium). Prior to transformation, the plasmid vector was treated with the restriction endonuclease <i>Not</i>I in order to remove the <i>bla</i> gene from the DNA fragment containing the <i>cry1Ab</i> and <i>pat</i> genes.</p>

<p style="text-align: justify;">Constitutive expression of the <i>cry1Ab</i> gene was controlled by the 35S promoter derived from cauliflower mosaic virus (CaMV) modulated by the IVS6 intron (from maize alcohol dehydrogenase 1S gene), and the 3&#39;-polyadenylation signal of the nopaline synthase (nos) gene from <i>Agrobacterium tumefaciens</i>. The phosphinothricin acetyltransferase (<i>pat</i>) gene was present as a selectable marker enabling identification of the transformed plant cells and to provide field tolerance to glufosinate ammonium. Constitutive expression of the <i>pat</i> gene was under the control of the CaMV 35S promoter, the IVS 2 intron, and NOS 3&#39; terminator.</p>

<p style="text-align: justify;">The plasmid pZO1502 also contained the beta lactamase (<i>bla</i>) gene included as selectable marker to screen transformed bacterial cells. The <i>bla</i> gene codes for a beta-lactamase enzyme that confers resistance to some beta-lactam antibiotics, including the moderate-spectrum penicillin and ampicillin. Bacterial cells that contained the pZ01502 plasmid were selected through their resistance to ampicillin. The <i>bla</i> gene was excised from the plasmid vector prior to transformation of the maize tissue.</p>

<p style="text-align: justify;">Other genetic components incorporated included a nonfunctional <i>lac</i>Z gene, encoding a portion of the enzyme beta-galactosidase; and the pUC origin of replication derived from the plasmid pBR322.</p>

<p style="text-align: justify;">Following the transformation event, plants were regenerated and the pollen of maize plants (<i>Zea mays</i> L.) derived from transformation event BT11 was used to pollinate the female flowers of an inbred maize line. Descendants of the initial crossings were successively back-crossed to evaluate different maize lines carrying the BT11 event. Several hybrid maize varieties have been derived from the Bt11 maize event.</p>
