<p style="text-align: justify;">Maize, or corn (<i>Zea mays</i> L.) is grown commercially in over 100 countries with a combined harvest of nearly 700 million metric tonnes in 2006. The top five producers of maize in 2005 were the United States, China, Brazil, Argentina, and Mexico, accounting for 70% of world production. Maize is grown primarily for its kernel (grain), the majority of which is used for animal feed, but with significant amounts refined into products used in a wide range of food, medical, and industrial goods.</p>

<p style="text-align: justify;">Maize is a raw material for the manufacture of starch, the majority of which is converted by a complex refining process into sweeteners, syrups, and fermentation products, including ethanol. Maize oil is extracted from the germ of the maize kernel. Only a small proportion of the whole kernel is consumed by humans (e.g., corn meal, grits, oil), while refined maize products such as sweeteners, starch, and oil are abundant in processed foods (e.g., breakfast cereals, dairy goods, chewing gum). Maize is also processed into masa, which is used for tortillas, tacos and corn chips.</p>

<p style="text-align: justify;">In the United States maize is typically used as animal feed, with roughly 70% of the crop fed to livestock, however a growing amount is now being used for the production of ethanol. The entire maize plant, the kernels, and several refined products such as glutens and steep liquor, are used in animal feeds. Silage made from the whole maize plant makes up 10-12% of the annual corn acreage, and is a major ruminant feedstuff. Livestock that feed on maize include cattle, pigs, poultry, sheep, goats, fish and companion animals.</p>

<p style="text-align: justify;">Industrial uses for maize products include recycled paper, paints, cosmetics, car parts. Refined maize products are also used in bioproducts such as antibiotics.</p>

<p style="text-align: justify;">The transgenic maize line LY038 was genetically engineered to increase the level of the amino acid lysine in the grain for animal feed, primarily for poultry and swine. Poultry and swine diets based on maize grain are usually supplemented with lysine. The use of LY038 as a feed ingredient is expected to reduce or eliminate the need for lysine supplementation. The maize line LY038 contains the <i>cordapA</i> gene from <i>Corynebacterium glutamicum</i> , which was introduced using micro-projectile bombardment of maize callus cells.</p>

<p style="text-align: justify;">The <i>cordapA</i> gene isolated from <i>Corynebacterium glutamicum</i>, codes for the enzyme dihydrodipicolinate syntase (cDHDPS). This enzyme is active in the lysine metabolic pathway and mediates a critical rate-limiting step, that in maize, is controlled by feedback inhibition. DHDPS catalyzes the condensation of L-aspartate-4-semialdehyde and pyruvate , resultling in the synthesis of 2,3-dihydrodipicolinate, a substrate in the lysine metabolic pathway. The DHDPS encoded by <i>cordapA</i> is less sensitive to feedback inhibition than the native maize DHDPS. The reduction in feedback inhibition results in higher levels of free lysine accumulating in the grain of LY038, at levels higher than those typically found in conventional maize.</p>
