Monitoring Identity and Metabolism Of Transgenic Plants

A major principle and guiding tool for the food safety assessment of genetically engineered (GE) crops is the concept of “substantial equivalence” according to principles outlined in the Organization for Economic Cooperation and Development (OECD) consensus documents and further elaborated by the Food and Agriculture Organization of the United Nations/World Health Organization. The metabolic changes of bacterial blight-resistant line C418/Xa23 generated by molecular marker-assisted selection (n=12), transgenic variety C418-Xa21 generated by using the Agrobacterium-mediated system (n=12), and progenitor cultivar C418 (n=12) were monitored using gas chromatography/mass spectrometry. The validation, discrimination, and establishment of correlative relationships between metabolite signals were performed by cluster analysis, principal component analysis, and partial least squares-discriminant analysis. Significant and unintended changes were observed in 154 components in C418/Xa23 and 48 components in C418-Xa21 compared with C418 (P < 0.05, Fold change > 2.0). The most significant decreases detected (P < 0.001) in both C418/Xa23 and C418-Xa21 were in three amino acids: glycine, tyrosine, and alanine, and four identified metabolites: malic acid, ferulic acid, succinic acid, and glycerol. Linoleic acid was increased specifically in C418/Xa23 which was derived from traditional breeding. This line, possessing a distinctive metabolite profile as a positive control, shows more differences vs. the parental than the transgenic line. Only succinic acid that falls outside the boundaries of natural variability between the two non-transgenic varieties C418 and C418/Xa23 should be further investigated with respect to safety or nutritional impact.