Proteome changes in tomato lines transformed with phytoene synthase-1 in the sense and antisense orientations

Abstract

The commercial cultivation of genetically engineered (GE) crops in Europe has met with considerable consumer resistance, which has led to vigorous safety assessments including the measurement of substantial equivalence between the GE and parent lines. This necessitates the identification and quantification of significant changes to the metabolome and proteome in the GE crop. In this study, the quantitative proteomic analysis of tomato fruit from lines that have been transformed with the carotenogenic gene phytoene synthase-1 (Psy-1), in the sense and antisense orientations, in comparison with a non-transformed, parental line is described. Multidimensional protein identification technology (MudPIT), with tandem mass spectrometry, has been used to identify proteins, while quantification has been carried out with isobaric tags for relative and absolute quantification (iTRAQ). Fruit from the GE plants showed significant alterations to their proteomes compared with the parental line, especially those from the Psy-1 sense transformants. These results demonstrate that MudPIT and iTRAQ are suitable techniques for the verification of substantial equivalence of the proteome in GE crops.

Fig. 1.

Workflow for identification and quantification of iTRAQ-labelled peptides from tomato.

Fig. 2.

Technical and biological replicates of proteins identified in each tomato cultivar. Each sample was injected twice (injection 1 and 2), whilst four biological replicates were analysed from each cultivar (1–4, 5–8, 9–12, and 13–16). Using ANOVA, there were no significant differences between injections 1 and 2 for each line, nor for intraplant variability (F > 0.05)

Fig. 3.

Box whisker plots displaying the ANOVA values of proteins from the four lines characterized in the iTRAQ experiments.

Fig. 4.

Categories and numbers of proteins identified in tomato lines.