The Role of Plant Endogenous Peptides in Cell Death Regulation

Abstract

Cell death is a ubiquitous process in all organisms and is often associated with autoimmunity. Precise control of cell death is crucial for plant survival; however, this process remain poorly understood in plants. Cell surface-resident immune receptors are the frontlines of the plant immune system. A major group of plant immune receptors are plasma membrane-resident receptor-kinases (RKs), for example, FLS2 perceiving a conserved region from bacteria called flagellin and triggering plant defense responses. The scientific model plant Arabidopsis thaliana genome encodes more than 600 RKs and more than 1000 putative ligands peptides. So far, most of them do not have their function characterized. Ligand perception by RKs often recruits to form a complex with another coreceptor. BAK1, also named somatic embryogenesis receptor kinase 3 (SERK3), is a common coreceptor for multiple RKs involved in plant immunity, growth, and development. Intriguingly, the depletion of BAK1 and its closest family member SERK4 triggers spontaneous cell death when the plants are 2 weeks old. By deploying a reliable and fast genetic screen for bak1/serk4 cell death suppressors, our lab identified mutants of an RK suppresses bak1-4/serk4 cell death. Since this RK localizes to the plasma membrane, our interest it to investigate the involvement of endogenous peptides to act as receptor ligands and regulate bak1/serk4 cell death. Characterization of peptide ligands and receptors in bak1/serk4 cell death regulation offers an insight into the molecular and physiological mechanism underlying plant cell death and autoimmunity.