Tubers from potato lines expressing a tomato Kunitz protease inhibitor are substantially equivalent to parental and transgenic controls

Summary Recombinant protease inhibitors represent useful tools for the development of insect‐resistant transgenic crops, but questions have been raised in recent years about the impact of these proteins on endogenous proteases and chemical composition of derived food products. In this study, we performed a detailed compositional analysis of tubers from potato lines expressing the broad‐spectrum inhibitor of Ser and Asp proteases, tomato cathepsin D inhibitor ( Sl CDI), to detect possible unintended effects on tuber composition. A compositional analysis of key nutrients and toxic chemicals was carried out with tubers of Sl CDI‐expressing and control (comparator) lines, followed by a two‐dimensional gel electrophoresis (2‐DE) proteomic profiling of total and allergenic proteins to detect eventual effects at the proteome level. No significant differences were observed among control and Sl CDI‐expressing lines for most chemicals assayed, in line with the very low abundance of Sl CDI in tubers. Likewise, proteins detected after 2‐DE showed no quantitative variation among the lines, except for a few proteins in some control and test lines, independent of sl cdi transgene expression. Components of the patatin storage protein complex and Kunitz protease inhibitors immunodetected after 2‐DE showed unaltered deposition patterns in Sl CDI‐expressing lines, clearly suggesting a null impact of sl cdi on the intrinsic allergenic potential of potato tubers. These data suggest, overall, a null impact of sl cdi expression on tuber composition and substantial equivalence between comparator and Sl CDI‐expressing tubers despite reported effects on leaf protein catabolism. They also illustrate the usefulness of proteomics as a tool to assess the authenticity of foods derived from novel‐generation transgenic plants.