Editing Bacterial conjugation (section)

==Inter-kingdom transfer==
[[File:Agrobacteriumgall.jpg|thumb|''Agrobacterium tumefaciens'' gall at the root of ''Carya illinoensis''.]]
Bacteria related to the [[diazotroph|nitrogen fixing]] ''[[Rhizobia]]'' are an interesting case of inter-[[Kingdom (biology)|kingdom]] conjugation.<ref>{{cite journal |last1=Pan |first1=Shen Q. |last2=Jin |first2=Shouguang |last3=Boulton |first3=Margaret I. |last4=Hawes |first4=Martha |last5=Gordon |first5=Milton P. |last6=Nester |first6=Eugene W. |title=An Agrobacterium virulence factor encoded by a Ti plasmid gene or a chromosomal gene is required for T-DNA transfer into plants |journal=Molecular Microbiology |date=July 1995 |volume=17 |issue=2 |pages=259–269 |pmid=7494475 |doi=10.1111/j.1365-2958.1995.mmi_17020259.x |s2cid=38483513}}</ref> For example, the tumor-inducing (Ti) plasmid of ''[[Agrobacterium]]'' and the root-tumor inducing (Ri) plasmid of ''A. rhizogenes'' contain genes that are capable of transferring to plant cells. The expression of these genes effectively transforms the plant cells into [[opines|opine]]-producing factories. Opines are used by the bacteria as sources of nitrogen and energy. Infected cells form [[Agrobacterium tumefaciens|crown gall]] or [[Agrobacterium rhizogenes|root tumors]]. The Ti and Ri plasmids are thus [[endosymbiont]]s of the bacteria, which are in turn endosymbionts (or parasites) of the infected plant.{{cn|date=February 2023}}

The Ti and Ri plasmids can also be transferred between bacteria using a system (the ''tra'', or [[Transfer gene|transfer, operon]]) that is different and independent of the system used for inter-kingdom transfer (the ''vir'', or [[virulence]], operon). Such transfers create virulent strains from previously avirulent strains.{{cn|date=February 2023}}