Rhizobia transform legume nodules via native T-DNA transfer systems

Native rhizobia-mediated transformation delivers mini-T-DNAs into root nodules of common bean, pea, and chickpea, where cargo genes are expressed, with no signal in adjacent root tissue.

• Why it matters: Agrobacteria-mediated transformation has been treated as a unique evolutionary innovation, but the extent of related DNA-transfer capabilities in rhizobia and their plant targeting is unclear.
• What they did: Screening 63,759 alphaproteobacterial genomes for T-DNA border sequences uncovered mini-T-DNAs across diverse rhizobial genera; RMT delivery was tested in legume root nodules.
• The result: RMT systems use VirG-dependent activation of the core virulence regulon yet respond to distinct upstream signals, and genome phylogenies place them in two T4SS clades distinct from AMT.

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