Horizontal gene transfer has played an important role in the evolution of bacterial genomes. In this review, we outline the factors influencing bacterial utilization of horizontally transferred DNA with reference to the capture of plant transgenes in the phytosphere; including soil, rhizosphere, phyllosphere and the digestive tracts of soil mesofauna invertebrates. Moreover, the release of transgenic plant DNA in the phytosphere and the transfer of bacterial genes in plant environments by natural transformation is reviewed.  Some characteristics of transgenes in transplastomic plants that may increase their likelihood of horizontal gene transfer are identified. Finally, new avenues for future studies with special reference to the elucidation of possible impacts of plant transgenes on the bacterial gene pool are suggested.