Deciphering the receptor kinase FERONIA: Functions and underlying mechanisms

Abstract: FERONIA (FER), a plasmamembrane-localized receptor kinase plays vital roles in plant growth development and stress responses. In the past decade, ligands, co-receptors, and many signaling components have been identified to shine light on the regulatory mechanisms. However, a comprehensive signaling network underlying FER-mediated diverse processes is still lacking. To this end, and also to facilitate the discovery of novel FER-mediated pathways, we carried out transcriptomic, proteomic and phosphoproteomic analyses. From the transcriptome analysis, we discovered that FER is a major negative regulator of plant hormone Jasmonic acid (JA) signaling. Further genetics, biochemistry and cell biology experiments demonstrate that FER phosphorylates and destabilizes MYC2 to inhibit JA signaling and MYC2-mediated host plant susceptibility, which establishes FER as a positive regulator in bacterial pathogen defense. RALF23, a rapid alkalization factor and a peptide ligand for FER, functions through FER to negatively contribute to bacterial defense. The proteome analysis validates previous findings such as negative regulation of FER on JA, and supports a role of FER in maintaining nutrient and energy homeostasis. The phosphoproteomics data analysis identified a group of transcription factors that potentially carry out diverse functions. The omics data has also revealed novel FER-mediated processes. The dissertation research establishes RALF23-FERONIA-MYC2, a ligand-receptor-transcription factor signaling module, as one of the underlying mechanisms for FER-mediated bacterial defense. Further studies on the newly identified candidate substrate transcription factors and novel pathways will broaden our understanding on how FERONIA, a plasmamembrane-localized receptor kinase, regulates plant growth development and stresses responses