Traceability of genetically modified (GM) foods demands the development of appropriate reliable techniques in order to identify and quantify peptide or nucleic acid residues in GM plants and food products through the food chain. In this study the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was demonstrated for the characterization of proteins of transformed and untransformed potato (Solanum Tuberosum L.) tubers. In GM tubers the expression level of the G1-1 gene, which regulates transition from dormancy to sprouting tubers, was inhibited by antisense technology. The analysis of antisense transformed lines showed that several of them exhibited a significant delay in sprouting relative to the control lines, in accordance with a decrease in the transcript level. Preliminary attempts to compare the protein patterns obtained from transformed and control lines using traditional electrophoresis were not able to reveal differences in the low-kDa range. Instead, MALDI-TOFMS applied to total peptide extract without any purification was able to distinguish spectral patterns of transformed and untransformed lines. In particular, several characteristic peaks from m/z 4373 to 4932 were detected only in the mass spectra of GM tuber samples.
Copyright 2003 John Wiley & Sons, Ltd.