Rhizobial type III effectors as regulators of root-nodule symbiosis in legumes.

Rhizobial Type III effectors directly regulate root-nodule symbiosis by targeting NF receptors and activating nodulation independently of NF perception.

• Why it matters: Understanding how rhizobial effectors influence symbiosis is crucial because it reveals mechanisms beyond immune suppression and host compatibility, impacting nodule formation and plant-microbe interactions.
• What they did: The study reviews recent findings on rhizobial effectors, including NopT, NopM, NopL, NopP, and NopZ, which target NF receptors or kinases, and ET-Nods that activate nodulation through rewiring host signalling, tracing their evolutionary origins.
• The result: These effectors are shown to act as specialised modulators of symbiosis signalling hubs, which may enhance partner selection or reduce host control, highlighting their role in the evolution of rhizobial symbiotic strategies.