Transfer of the Symbiotic Plasmid of CFN42 to Endophytic Bacteria Inside Nodules.

Conjugative transfer is one of the mechanisms allowing diversification and evolution of bacteria. CFN42 is a bacterial strain whose habitat is the rhizosphere and is able to form nodules as a result of the nitrogen-fixing symbiotic relationship it may establish with the roots of . CFN42 contains one chromosome and six large plasmids (pRet42a - pRet42f).

Conjugative transfer between Rhizobium etli endosymbionts inside the root nodule.

Since the discovery that biological nitrogen fixation ensues in nodules resulting from the interaction of rhizobia with legumes, nodules were thought to be exclusive for hosting nitrogen-fixing and plant growth promoting bacteria. In this work, we uncover a novel function of nodules, as a niche permissive to acquisition of plasmids via conjugative transfer. We used Rhizobium etli CFN42, which nodulates Phaseolus vulgaris.