The Manifold Actions of Signaling Peptides on Subcellular Dynamics of a Receptor Specify Stomatal Cell Fate

Abstract

21Receptor endocytosis is important for signal activation and transduction. However, how a receptor 22interprets conflicting signals to adjust cellular output is not clearly understood. During plant 23 development, the family of EPIDERMAL PATTERNING FACTOR (EPF) peptides fine-tunes 24 stomatal patterning through ERECTA-family receptor kinases. Using genetic, cell biological, and 25 pharmacological approaches, we report here that ERECTA-LIKE1 (ERL1), the major receptor 26 restricting stomatal differentiation, undergoes dynamic subcellular behaviors in response to 27 different signal inputs. ERL1 is constitutively recycled, whereas its activation by EPF1 peptide 28 induces rapid internalization to multivesicular bodies (MVB). In contrast, dominant-negative ERL1 29 resides predominantly in plasma membrane. The co-receptor, TOO MANY MOUTHS (TMM), is 30 essential for EPF1-induced ERL1 internalization but dispensable for EPFL6-induced ERL1 31internalization. The peptide antagonist of EPF1, Stomagen/EPFL9, triggers retention of ERL1 in 32 the endoplasmic reticulum. Our study elucidates that multiple related yet unique peptides specify 33 cell fate by deploying the differential subcellular dynamics of a single receptor. 34 35 36 37