A kinase mediator of rhizobial symbiosis and immunity in Medicago.

Wang, Dapeng; Jin, Rui; Shi, Xiaobao; Guo, Haoran; Tan, Xinhang; Zhao, Achen; Lian, Xinghua; Dai, Huiling et al. · Nature · 2025

basic_science · Level V

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Abstract

Legume roots secure nitrogen by forming a symbiosis with soil rhizobia but remain resistant to pathogenic bacteria<sup>1-4</sup>. How this tolerance to rhizobia is achieved without compromising plant immunity is largely unknown. Here we identify the cytoplasmic kinase MtLICK1/2, which interacts with nodulation factor receptor MtLYK3 to drive symbiotic signalling and suppress plant immunity. Rhizobial infection and nodule development are defective in Mtlick1/2, phenocopying the Mtlyk3-1 mutant. MtLICK1/2 and MtLYK3 undergo reciprocal transphosphorylation during rhizobial symbiosis. Phosphorylated MtLYK3 activates the receptor-like kinase MtDMI2 to stimulate symbiotic signalling. MtLICK1/2 is activated in the rhizobial infection area to suppress plant immunity. Thus, MtLICK1/2 and MtLYK3 together amplify symbiotic signalling and dampen host immunity to enable legume-rhizobium symbiosis.

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