Molecular Characterization and Assessment of Insect Resistance of Transgenic Maize ZDRF-8

ZDRF-8 is a transgenic maize event created via <i>Agrobacterium</i>-mediated transformation for insect resistance and glyphosate tolerance by expressing <i>Cry1Ab</i>, <i>Cry2Ab</i>, and <i>G10evo-epsps</i>. A Southern blot analysis suggested that it is a single-copy T-DNA insertion event. The flanking genomic sequences of the T-DNA insertion suggested that its T-DNA was inserted at the terminal region of the long arm of chromosome 7 without interrupting any known or predicted genes. Event-specific PCRs based on the flanking sequence were able to detect this event specifically. Laboratory bioassays and field trials of multiple generations demonstrated that ZDRF-8 is highly active against major corn pests in China, including Asian corn borers (ACB, <i>Ostrinia furnacalis</i>), cotton bollworms (CBW, <i>Helicoverpa armigera</i>), and oriental armyworm (OAW, <i>Mythimna separata</i>), and meanwhile confers glyphosate tolerance up to two times the recommended dose. The expression of the transgenes and the efficacy of insect resistance and glyphosate tolerance were stable over more than 10 generations. ZDRF-8 has been granted with a safety certificate in China, and its commercial release is expected in the coming years.