Receptor kinase THESEUS1 is a RALF 34 receptor with roles in lateral root development (Curr. Biol.)

RALF peptides were identified nearly 20 years ago, as small peptides that induce rapid alkalinisation of the culture medium when added to cell suspension cultures.  Previously, members of the receptor-like kinase  (RLK) family including FERONIA (FER) have been identified as RALF receptors.  A related RLK, THESEUS1 (THE1), was known to have a role in cell wall sensing and responses, but its ligand was not known. Now,  Gonneau and  Desprez et al. have shown that RALF34 is a ligand for THE1. The biological relevance of this interaction was demonstrated by several methods including genetics, co-occuring expression domains, and downstream gene expression studies, as well as micro-scale thermophoresis (MST) binding assays. The authors also demonstrate an important role for the THE1/RALF34 interaction in lateral root initiation. (Summary by Mary Williams) Curr. Biol. 10.1016/j.cub.2018.05.075