Proteomic analysis of a genetically modified maize flour carrying Cry1Ab gene and comparison to the corresponding wild-type

Protein expression in a maize hybrid flour (hereafter called WT) and its corresponding transgenic version resistant to European corn borer (hereafter called BT and carrying a gene encoding for the Bacillus thuringiensis insecticidal protein Cry1Ab) has been studied by means of two-dimensional gel electrophoresis coupled with mass spectrometry. This comparison has been chosen as a model to verify proteomics capability in detecting unexpected differences between near-isogenic lines (differing in the ideal case only for the presence of the transgenic protein). Some unpredictable differences were detected: i) glucose and ribitol dehydrogenase spot was unique of BT maize; ii) endochitinase A spot was unique of WT maize; iii) triosephosphate isomerase 1 and one spot of globulin-1 S were overexpressed while cytosolic 3-phosphoglycerate kinase and one spot of aldose reductase were down-regulated in BT maize with respect to WT. These results outline the potential of the new non-targeted "-omics" technologies (in particular proteomics) in the detection of unexpected, unintended and unwanted variations in Genetically Modified (GM) versus non-GM food comparison and suggest the possible employment of these technologies in substantial equivalence evaluation. Moreover, a reference map for maize flour was built: forty spots, corresponding to twenty-five different proteins, were successfully identified.