<p style="text-align: justify;">This product was not subject to regulation in any jurisdiction except Canada since the development of this herbicide-tolerant line did not employ recombinant DNA technologies. In Canada, regulatory approval was required for use in human food and livestock feed, but not for environmental release as these lines were not intended for cultivation in Canada.</p>

<p style="text-align: justify;">Harvested rice, or rough rice, is encased by an inedible hull or husk, which is removed before milling. The hulls are utilized as fuels, mulch, abrasives and animal feed products. Brown rice is what remains after the hulls are removed. The light brown colour of brown rice is due to the presence of bran layers and the rice germ surrounding the rice kernel. Brown rice can be milled into regular white or &lsquo;polished rice&rsquo;, where white rice is distinguished by the fact that the hulls, bran layers and rice germ are removed. The bran and rice germs are high in protein and nutrients and are used in specialty foods such as rice bran oil and also in livestock feed. Both brown and white rice kernels can be parboiled and/or milled into rice flour for use in breakfast cereals, baby foods and desserts and numerous other food products. Rice kernels are also used to produce beer and rice wine.</p>

<p style="text-align: justify;">Weeds are a significant production problem in rice cultivation. Weeds of rice producing areas, such as the United States, include red rice (<i>Oryza</i> spp.), barnyard grass, sprangletop, fall panicum, large crabgrass, rice flatsedge, yellow nutsedge, and smartweed. These are typically managed using a combination of cultural practices (e.g., dry <i>vs</i> wet tillage, using clean seed, crop rotations) and chemical controls (herbicides such as molinate and propanil).</p>

<p style="text-align: justify;">Rice lines CL121, CL141, and CFX51, were developed through a combination of accelerated mutagenesis and traditional cross-breeding to exhibit tolerance to imidazolinone containing herbicides, such as imazethapyr. Imidazolinone herbicides are active against the acetolactate synthase (ALS) enzyme in plants, which catalyzes the first reaction in the biosynthesis of branched-chain amino acids. Imidazolinone inhibits the production of these essential amino acids (valine, leucine and isoleucine), resulting in a decrease in protein synthesis and the eventual death of the plant. ALS is also active in the glycolytic pathway of plant metabolism, by which sugars are broken down to produce acids and release energy.</p>

<p style="text-align: justify;">The original mutant line, 93AS3510, was used as a parental line in a breeding program with Cocodrie, Maybelle, and Cypress rice varieties to create lines CL121, CL141, and CFX51, respectively.</p>
