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Label-free quantitative proteomic (LFQ) and widely targeted metabolomic analyses were applied in the safety evaluation of three genetically modified (GM) maize varieties, BBL, BFL-1, and BFL-2, in addition to their corresponding non-GM parent maize. A total of 76, 40, and 25 differentially expressed proteins (DEPs) were screened out in BBL, BFL-1, and BFL-2, respectively, and their abundance compared was with that in their non-GM parents. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that most of the DEPs participate in biosynthesis of secondary metabolites, biosynthesis of amino acids, and metabolic pathways. Metabolomic analyses revealed 145, 178, and 88 differentially accumulated metabolites (DAMs) in the BBL/ZH58, BFL-1/ZH58, and BFL-2/ZH58×CH72 comparisons, respectively. KEGG pathway enrichment analysis showed that most of the DAMs are involved in biosynthesis of amino acids, and in arginine and proline metabolism. Three co-DEPs and 11 co-DAMs were identified in the seeds of these GM maize lines. The proteomic profiling of seeds showed that the GM maize varieties were not dramatically different from their non-GM control. Similarly, the metabolomic profiling of seeds showed no dramatic changes in the GM/non-GM maize varieties compared with the GM/GM and non-GM/non-GM maize varieties. The genetic background of the transgenic maize was found to have some influence on its proteomic and metabolomic profiles.

The phosphinothricin N-acetyltransferase gene (pat) is widely used to confer resistance to the herbicide phosphinothricin for genetically modified (GM) crops. A quantitative sandwich enzyme-linked immunosorbent assay (ELISA) is developed to detect PAT/pat in GM crops. Two anti-PAT/pat monoclonal antibodies (mAbs), 1F5-1F2 and 1B6-2D3, with titers of 1:1,024,000 and 1:896,000, respectively, against overexpressed His-PAT/pat, were screened out, raised, and characterized. An ELISA method was established with the 1F5-2F2 mAb for capture and the biotin-labeled 1B6-2D3 mAb for detection of PAT/pat. The linear detection range of the method was approximately 1.5625–12.5 ng/mL, with a sensitivity of 0.085 ng/mL and a coefficient of variation (CV) less than 5.0%. No cross-reactivity was found with other herbicide resistance proteins, especially PAT/bar. The established sensitive and specific ELISA was successfully applied in the detection of PAT/pat expression in GM crops.