<p style="text-align: justify;">Maize line MON88017 was genetically modified to contain two novel genes, <i>cry</i>3Bb1 for insect resistance, and <i>cp4 epsps</i>, which confers tolerance to glyphosate. Both genes were introduced into the parental maize line LH198 by <i> Agrobacterium</i>-mediated plant transformation.</p>

<p style="text-align: justify;">The <i>cry</i>3Bb1 gene, isolated from the soil bacterium <i>Bacillus thuringiensis</i> (Bt) subspecies <i>kumamotoensis</i>, produces the insect control protein Cry3Bb1, a delta-endotoxin. Cry proteins, of which Cry3Bb1 is only one, act by selectively binding to specific sites localized on the lining of the midgut of susceptible insect species. Following binding, pores are formed that disrupt midgut ion flow, causing gut paralysis and eventual death due to bacterial sepsis. Cry3Bb1 is lethal only when eaten by the larvae of coleopteran insects (<i>i.e.</i>, beetles), and its specificity of action is directly attributable to the presence of specific binding sites in the target insects. There are no binding sites for the delta-endotoxins of <i>B. thuringiensis</i> on the surface of mammalian intestinal cells, therefore, livestock animals and humans are not susceptible to these proteins. The Cry3Bb1 protein expressed in MON88017 provides protection against the western corn rootworm (<i>Diabrotica vigifera</i>) and northern corn rootworm (<i>Diabrotica barberi</i>).</p>

<p style="text-align: justify;">MON88017 also was developed to allow the use of glyphosate, the active ingredient in the herbicide Roundup&reg;, as a weed control option. The novel plants express an herbicide tolerant form of the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) derived from the common soil bacterium, <i>Agrobacterium tumefaciens</i> strain CP4. Glyphosate specifically binds to and inactivates EPSPS, which is involved in the synthesis of the aromatic amino acids, tyrosine, phenylalanine and tryptophan (shikimate biochemical pathway). EPSPS is present in all plants, bacteria, and fungi but not in animals, which must obtain these essential amino acids from their diet. Because the aromatic amino acid biosynthetic pathway is not present in mammalian, avian or aquatic life forms, glyphosate has little if any toxicity for these organisms (U.S. EPA, 1993; WHO, 1994; Williams et al. 2000). The EPSPS enzyme is normally present in food derived from plant and microbial sources.</p>
