Mechanisms of T-DNA integration

T-DNA integration is the final step of the transformation process. During this step, the T-DNA, which traveled as a single-stranded DNA molecule from the bacterial cell through the host-cell cytoplasm into the nucleus, must covalently attach itself to the host cell's double-stranded genomic DNA. To fulfil its destiny, the T-DNA needs to be directed to its point of integration in the host genome, to be stripped of some, if not all, of its bacterial and host escorting proteins, and to interact with and co-opt the host's DNA-repair proteins and machinery for its complementation into a double-stranded DNA molecule during its integration into the host genome. In the following chapter, we describe the current knowledge on the functions performed by the bacterial and host proteins, and the role that the host genome may play, during the integration process. We also present the dominant models used today to explain the complex mechanism of T-DNA integration in plant cells.