A Lotus japonicus cytoplasmic kinase connects Nod factor perception by the NFR5 LysM receptor to nodulation

Significance Legume receptors perceive Nod factor signal molecules at the plasma membrane of epidermal cells and initiate a signal transduction process that leads to the development of root nodules that house nitrogen-fixing rhizobia. Nodule organs are formed by reinitiation of cell divisions in already differentiated root cells. Previous genetic screens have identified plant genes involved in nodulation; however, the receptor-triggered relay mechanism activating the developmental program in the nucleus is still unknown. We present a proteomics approach that identified proteins that associate with the Lotus japonicus Nod factor receptor 5 (NFR5), among which the NFR5-interacting cytoplasmic kinase 4 (NiCK4) appears to be an important link between Nod factor perception by NFR5 and nodule organogenesis.