TC1507 X NK603 (OECD identifier: DAS-Ø15Ø7-1 x MON-ØØ6Ø3-6) maize is an F1 hybrid resulting from the hybridization of the insect-resistant inbred maize TC1507 ( DAS-Ø15Ø7-1) with the herbicide-tolerant maize inbred NK603 (MON-ØØ6Ø3-6). This stacked maize hybrid is a product of traditional plant breeding, and therefore is not automatically subject to regulation in all jurisdictions as are transgenic plants resulting from recombinant DNA technologies. Certain jurisdictions may request notification in advance of the release of a stacked hybrid, or may request information to conduct an environmental and food safety assessment.  Examples of jurisdictions that require either notification or information about stacked hybrids prior to their release into the environment, and for use in human food and livestock feed are Canada and Japan.<br> <br>The stacked hybrid TC1507 X NK603 expresses three novel proteins: the delta-endotoxin Cry1F which confers resistance to the European Corn Borer and other lepidopterans, the PAT protein which confers tolerance to the herbicide glufosinate ammonium, and the CP4 EPSPS protein which confers resistance to the herbicide glyphosate.  The insecticidal protein is produced by the <i>cry</i>1F gene and PAT is produced by the <i>pat</i> gene, both from TC1507. The CP4 EPSPS protein is produced by the <i>cp4 epsps</i> gene from NK603. The novel traits of each parental line have been combined, through traditional plant breeding, to produce this new hybrid.  For a full description of each parental line please refer to the individual product descriptions in the crop database for <a href="dbase.php?action=ShowProd&data=TC1507&frmat=LONG"><b>TC1507</b></a> and <a href="dbase.php?action=ShowProd&data=NK603&frmat=LONG"><b>NK603</b></a>.<br>The inserted genes and their gene products have a history of safe use, and have undergone review and approval by several regulatory agencies.  No interactions among the gene products or negative synergistic effects are expected in the stacked hybrid.  The Cry1F protein is not an enzyme and therefore does not affect plant metabolism.  Both the PAT and CP4 EPSPS have high substrate affinities: PAT for L-Phosphinothricin, the active ingredient in glufosinate ammonium, and CP4 EPSPS for phosphoenolpyruvate (PEP) and shikimate-3-phosphate, which are part of the shikimate metabolic pathway.   Since both PAT and CP4 EPSPS differ in substrates and in mode of action, these are not expected to interact within, nor affect the metabolism of the stacked hybrid.  <br>Southern blot analysis has confirmed that <i>cry</i>1F, <i>pat</i> and <i>cp4 epsps</i> genes are stably inherited in the stacked hybrid.  The expression levels of Cry1F, PAT and CP4 EPSPS were comparable to those of the parental lines.  The stacked hybrid displayed the same degree of tolerance to the herbicides glufosinate ammonium and glyphosate, as the parental lines.  <br>Heterosis is expected in F1 hybrids.  An example of heterosis is a substantial increase in yield in the F1 hybrid compared to the parental lines.  The stacked hybrid TC1507 X NK603 is therefore expected to display heterosis, as would any conventional F1 hybrid.  Heterosis in this hybrid is not expected to be caused by the introduced genes, since the gene products are not expected to interact synergistically.