Antagonistic perception of endogenous peptides by FERONIA regulates plant immunity
M. STEGMANN (1), J. Monaghan (2), E. Smakowska (3), H. Roevenich (4), N. Holton (1), Y. Belkhadir (3), C. Zipfel (1) (1) The Sainsbury laboratory, United Kingdom; (2) Queens University, Canada; (3) Gregor Mendel Institute, Austria; (4) Wageningen University, Netherlands

Cell-surface receptor kinases play important roles in plant growth, development and immunity. The regulation of these receptor kinases and their potential interconnections are not well understood. Here, we report that immunity mediated by the Arabidopsis leucine-rich repeat receptor kinases FLS2 and EFR is modulated by the malectin receptor kinase FERONIA (FER) via the antagonistic perception of a family of endogenous peptides. The protease S1P and one of its substrates, the endogenous peptide RALF23, inhibit immunity. RALF23 cleavage by S1P is increased upon non-self perception and RALF23 directly binds to FER. Interestingly, non-S1P-cleaved RALF peptides have either no inhibitory activity, or in contrast act as agonists of immune signaling. Notably, one such peptide, RALF17, activates immunity in a manner that also depends on FER, which could explain our observation that FER behaves genetically as a positive regulator of immune signaling mediated by FLS2 and EFR, and of antibacterial immunity. Our data suggests that FER-mediated perception of non-S1P-cleaved RALF peptides potentiates immune signaling, while other RALF peptides cleaved by S1P upon non-self perception out-compete FER binding and thus inhibit indirectly immune signaling as part of a negative feedback loop regulation. Beyond immunity, our results expand the repertoire of FER ligands, and provide a theoretical template to explain the multiple roles played by FER and RALF peptides in diverse plant processes.

Abstract Number: P17-617
Session Type: Poster