Transcriptomic Analysis of the Impact of Transgene Insertion and Expression on the Endogenous Host Genome

It is important; as part of safety risk assessment during development and production of genetically modified (GM) crops; to include studies on the integration of the transgene within the host genome, the location of the transgene insertion site within the host genome, and sufficient biochemical and agronomic assays of the GM crop. Furthermore, it was highlighted that it is equally important to study the unpredictable and unintended effects of the insertion of a transgene into a host plant. Examples of these unpredictable and unintended effects include the expression of the transgene affecting endogenous gene expression, insertion of the transgene into an endogenous gene disrupting the function of the endogenous gene and production of new metabolites resulting from endogenous gene disruptions. A project was initiated to study the transcriptomics impact of the insertion and expression of a transgene within the host genome. The model plant for the study was a potato plant transformed with an apple antifungal gene for enhanced fungal disease resistance. Genome walking results revealed that the Agrobacterium-mediated transformation of the potato plant only resulted in the insertion of the T-DNA, that is, no non-T-DNA sequences from the binary vector was inserted into the potato genome. Gene expression studies showed that the transgene was located in a gene-rich area which corroborates literature findings. A few quantifiable differences were observed where endogenous PsaC, afg3, Stpgip1 and xth genes were up-regulated in the transgenic. However, these alterations were not major thus the transgenic potato is significantly equivalent to its traditional counterpart.