Pleiotropic effects on the transcriptome and genome of transgenic soybeans resulting from transgene integration and expression in seed tissue

The seeds of the common soybean (Glycine max) produce and store large amounts of protein, making them an appealing bioreactor for producing valuable recombinant proteins at high levels. However, the effects of accumulating recombinant protein at high levels on bean physiology are not well understood. To address this, we investigated whether gene expression within transgenic soybean seed tissue is significantly altered when large amounts of recombinant proteins are produced and stored in the seeds. Measurable unscripted gene expression changes were detected in the seed transcriptomes of three transgenic soybean lines chosen for analysis, with one line (764) exhibiting extensive gene expression changes. Further investigations revealed nucleotide polymorphism rates in line 764 nearly double that of the other two transgenic lines and wild type controls. In all three lines examined, the transgene insertions did not disrupt any currently annotated soybean genes. These results suggest that recombinant protein expression and accumulation in seed tissue may impact native gene expression, possibly due to chemical attributes of the particular recombinant protein being expressed or effects resulting from transformation mutagenesis rather than heterologous protein expression levels.