Abstract

Receptor Kinases (RKs) control essential aspects of plant’s life such as plant development or immunity. The largest family of RKs in plants is the leucine-rich repeat RKs (LRR-RKs), which is present in streptophyte algae but expanded in land plants. Ligand perception by LRR -RKs induces the association with a co-receptor that often belongs to the somatic embryogenesis RK (SERK) subfamily to activate downstream signaling. Combining phylogenetic analyses, structural predictions and functional assays in the bryophyte Marchantia polymorpha and the eudicot Arabidopsis thaliana, we discovered that SER Ks play conserved molecular functions in development but not immunity. Our results indicate that LRR -RK pattern-recognition receptors might require different activation mechanisms in different plant lineages. Furthermore, we showed that mutations in the Marchantia orthologs of RKs regulating immunity in Arabidopsis trigger an autoimmune response in Marchantia. These autoimmune mutants exhibited resistance against bacterial and fungal pathogens. Our comparative evolutionary approach highlights the power of Marchantia genetics to investigate the Evolution of Molecular Plant-Microbe Interactions in land plants.