Reprogramming, not silencing: How plant immunity is gated during legume nodulation

This is the authors' abstract. We don't add key points for this paper.

Legume– Rhizobium symbiosis requires rhizobial entry and intracellular persistence without triggering host defense. Recent genetic and biochemical studies support an immune-gating view in which plant immunity pathways are not simply suppressed, but are dynamically regulated throughout rhizobial infection, nodule development and nodule senescence. Here, we review how LysM/LRR receptor complexes and co-receptor availability shape early discrimination of symbiotic signals and immune elicitors and how shared signaling modules (Ca 2+ , ROS and MAPKs) are differentially regulated to permit infection and nodule organogenesis. We then discuss rhizobial surface polysaccharides and type III-secreted effectors as modulators of these thresholds and highlight nodule-local regulators that prevent late immune reactivation and maintain bacteroid accommodation. We also discuss nodule-specific, regulator autophagy-associated processes and, in some legumes, NCR peptides that maintain bacteroids within symbiosomes while preventing plant overactivation of immunity.