<p style="text-align: justify;">Soybean (<i>Glycine max</i>) is grown primarily for its seed, which has many uses in the food and industrial sectors, and represents one of the major sources of edible vegetable oil and of proteins for livestock feed use. The major producers of soybeans were the United States, Brazil, Argentina, China, India, Paraguay and Canada.</p>

<p style="text-align: justify;">A major food use of soybean in North America and Europe is as purified oil, used in margarines, shortenings, and cooking and salad oils. It is also a major ingredient in food products such as tofu, tempeh, soya sauce, simulated milk and meat products, and is a minor ingredient in many processed foods. Soybean meal is used as a supplement in feed rations for livestock.</p>

<p style="text-align: justify;">Weeds are a major production problem in soybean cultivation. Typically, weeds are managed using a combination of cultural (<i>e.g.</i> seed bed preparation, using clean seed, variety selection, and planting date) and chemical controls. Depending on the production area and the prevalent weed species, herbicides may be applied before planting (<i>e.g.</i> pendimethalin, trifluralin, metribuzin), after planting but before emergence (<i>e.g.</i> pendimethalin, linuron, imazethapyr), and/or after emergence (<i>e.g.</i> bentazon, acifluorfen, fomesafen). Commonly, several different herbicides are required to adequately control weeds in soybean fields.</p>

<p style="text-align: justify;">The soybean lines A2704-12, A2704-21, and A5547-35 were developed to allow for the use of glufosinate ammonium, the active ingredient in phosphinothricin herbicides (Basta&reg; , Ignite&reg; , Rely&reg; , Liberty&reg; , Harvest&reg; , and Finale&reg;) as a weed control option. These genetically engineered soybean lines contain the fungal enzyme phosphinothricin-N-acetyltransferase (PAT) that allows these plants to survive the otherwise lethal application of glufosinate. The <i>pat</i> gene inserted into A2704-12, A2704-21, and A5547-35 was isolated from a common soil fungus, <i>Streptomyces viridochromogenes</i>, and introduced into the soybean genome by particle acceleration (biolistic) transformation.</p>

<p style="text-align: justify;">The PAT enzyme in soybean lines A2704-12, A2704-21, and A5547-35 converts L-phosphinothricin (PPT), the active ingredient in glufosinate ammonium, to an inactive form thereby conferring resistance to the herbicide. In absence of PAT, application of glufosinate leads to reduced production of the amino acid glutamine and increased ammonia levels in the plant tissues which are lethal to the plant. The PAT enzyme is not known to have any toxic properties.</p>

<p style="text-align: justify;">Glufosinate-tolerant soybean lines A2704-12, A2704-21, and A5547-35 were tested in field trials in the United States (1990-1993) and line A2704-12 was field tested in Canada and Japan. These tests demonstrated that the transformed lines did not exhibit weedy characteristics, or negatively affect beneficial or nontarget organisms, and were not expected to impact on threatened or endangered species.</p>

<p style="text-align: justify;">Soybean does not have any weedy relatives with which it can crossbreed in the continental United States or Canada. Cultivated soybean can naturally cross with the wild annual species <i>G. soja</i>, however <i>G. soja</i>, which occurs naturally in China, Korea, Japan, Taiwan and the former USSR, is not naturalized in North America. Additionally, soybean plants are almost completely self-pollinated and reproductive and growth characteristics remained unchanged by the genetic modification resulting in glufosinate-tolerant soybean lines. It was therefore concluded that the potential for transfer of the glufosinate tolerance trait from the transgenic line to soybean relatives through gene flow (outcrossing) was negligible in managed ecosystems, and that there was no potential for transfer to wild species in Canada and the continental United States.</p>

<p style="text-align: justify;">The food and livestock feed safety of glufosinate-tolerant soybean lines A2704-12, A2704-21, and A5547-35 was established based on the lack of toxicity or allergenicity of the PAT protein and by direct laboratory analyses. The nutritional equivalence and wholesomeness of these soybeans compared to conventional (non-GM) soybeans was demonstrated by the analysis of key nutrients, including proximates (<i> e.g.</i>, moisture, crude protein, crude fat, ash, acid detergent fibre, neutral detergent fibre, carbohydrate), fatty acid analysis, amino acid analysis, and analyses of minerals (calcium, phosphorous, and potassium). This equivalence of glufosinate-tolerant soybeans to conventional soybeans was further confirmed in feeding studies with rats and broiler chickens.</p>
