There are several reports about natural plants with large part of Ri plasmid from A. rhizogenes, like those:
Intrieri MC, Buiatti M. The horizontal transfer of Agrobacterium rhizogenes genes and the evolution of the genus Nicotiana. Mol Phylogenet Evol. 2001 Jul;20(1):100-10.
Matveeva TV, et al. Horizontal gene transfer from genus agrobacterium to the plant linaria in nature. Mol Plant
Microbe Interact. 2012 Dec;25(12):1542-51.
Is there any chance that such DNA will be transformed from plant back to bacteria and will be functional?