The EFSA GMO panel assessed the stacked maize NK603xT25xDAS-40278-9, which is derived from crossing three genetically engineered maize events (EFSA, 2021a). The parental plants were assessed by EFSA in previous opinions. The maize contains genes conferring resistance to three herbicides: glufosinate, glyphosate, 2,4-dichlorophenoxyacetic acid (2,4-D) and aryloxyphenoxypropionate (AOPP) herbicides:
• NK603 expressing two variants of CP4 EPSPS protein for tolerance to glyphosate-containing herbicides;
• T25 expressing PAT to confer tolerance to glufosinate-ammonium containing herbicides and a large part of a β-lactamase (bla) gene of bacterial origin which provides resistance to antibiotics was inserted, but assumed to show no expression;
• DAS-40278-9 expressing AAD-1 to catalyse the degradation of the general class of herbicides known as aryloxyphenoxypropionates (AOPP) and to confer tolerance to 2,4-D containing herbicides.
Implementing Regulation 503/2013 has been applied in the risk assessment as performed by EFSA.