Control of T-DNA Transfer from Agrobacterium tumefaciens to Plants Based on an Inducible Bacterial Toxin-Antitoxin System.

High-value pharmaceutical products are already successfully produced in contained facilities using Agrobacterium-mediated transient transformation of plants. However, transfection methods suitable for open field applications are still desirable as a cheaper alternative. Biosafety concerns related to the use of recombinant agrobacteria in an industrial transfection process include possible transformation or transfection of unintended hosts or spread of the genetically modified agrobacteria in the environment. In this paper, we explored a novel biocontrol approach resulting in greater biosafety of the transient expression process in plants. Our proposed solution involves inducible expression of Agrobacterium tumefaciens toxin PemK and antitoxin PemI that provides for strictly regulated T-DNA transfer from agrobacteria to plants. We also identified several other toxins from putative Agrobacterium toxin-antitoxin modules and demonstrate their potential usefulness in the control of Agrobacterium tumefaciens as a DNA vector.