<p style="text-align: justify;">DBT418 maize was produced by biolistic transformation of the inbred line DBT418 with DNA from three different plasmid vectors, respectively containing the <i>cry1Ac</i> gene from <i>B. thuringiensis</i>, the <i>bar</i> gene from <i>S. hygroscopicus</i>,and the protease inhibitor gene (<i>pinII</i>) from potato.</p>

<p style="text-align: justify;">Constitutive expression of the <i>cry1Ac</i> gene was under the control of a chimeric promotor consisting of the 35S promoter from cauliflower mosaic virus (CaMV) and two copies of the octopine synthase (OCS) enhancer from <i>Agrobacterium tumefaciens</i>. The OCS enhancer promotes the expression of genes in most vegetative tissues. An intron from a maize alcohol dehydrogenase gene (<i>adhI</i> intron VI) was positioned downstream from the promoter to enhance gene expression. The 3&#39;-terminal sequences from the potato <i>pinII</i> gene were used as a termination signal for the <i>cry1Ac</i> gene.</p>

<p style="text-align: justify;">Expression of the <i>bar</i> herbicide resistance gene was regulated using the CaMV 35S promoter and termination sequences from the Ttr7 transcript 7 polyadenylation region of the <i>A. tumefaciens</i> T-DNA. The third gene, <i>pinII</i> was under the control of the CaMV 35S promoter and <i>adhI</i> intron I but was not completely incorporated and therefore not expressed.</p>

<p style="text-align: justify;">Each plasmid also included a beta-lactamase (<i>bla</i>) gene which encodes resistance to the antibiotic ampicillin. The beta-lactamase gene was derived from <i>E. coli</i> and expression was under the control of its own bacterial promoter. This gene was included as a selectable marker to identify bacteria transformed with recombinant plasmid DNAs, but is not functional in plants.</p>
