title: A two-year assessment of the environmental impact of transgenic high-methionine soybean on rhizosphere bacterial communities
design: To elucidate whether the GM crops alter the rhizospheric bacterial community structure, a two-year (2012 and 2013) field trial was performed with transgenic high-methionine soybean ZD91 and its near-isogenic control ZD. Soil DNA was extracted from the rhizosphere soil samples by employing the MoBio PowerSoil DNA Isolation Kit. The 16S rRNA gene (V4 region) was amplified using the PCR primers 515F and 806R. The community composition and abundance of bacteria in the rhizosphere soil were assessed at different growth stages of soybean by 16S rRNA amplicon sequencing. Results obtained over two years did not reveal significant differences between the transgenic soybean and the control. Conclusively, the transgenic soybean ZD91 did not indicate an adverse impact on rhizosphere bacterial communities. The structure of the communities was shown to be less affected by the transgenic soybean as compared to environmental factors such as plant age or year.