Receptor kinase complex transmits RALF peptide signal to inhibit root growth in Arabidopsis

Abstract

A number of hormones work together to control plant cell growth. Rapid Alkalinization Factor 1 (RALF1), a plant-derived small regulatory peptide, inhibits cell elongation through suppression of rhizosphere acidification in plants. Although a receptor-like kinase, FERONIA (FER), has been shown to act as a receptor for RALF1, the signaling mechanism remains unknown. In this study, we identified a receptor-like cytoplasmic kinase (RPM1-induced protein kinase, RIPK), a plasma membrane-associated member of the RLCK-VII subfamily, that is recruited to the receptor complex through interacting with FER in response to RALF1. RALF1 triggers the phosphorylation of both FER and RIPK in a mutually dependent manner. Genetic analysis of the fer-4 and ripk mutants reveals RIPK, as well as FER, to be required for RALF1 response in roots. The RALF1-FER-RIPK interactions may thus represent a mechanism for peptide signaling in plants.plant hormone | feronia | phosphorylation

Plant Lectins and Lectin Receptor-Like Kinases: How Do They Sense the Outside?

“…However, the FER domains involved in RAFL binding are not known. FER is also able to recruit a receptor-like cytoplasmic kinase that is phosphorylated by FER in a RALF peptide-dependent manner [166]. Finally, FER is required for the signalling of mechanical forces [167] and the FER/RALF couple is linked to ABA signalling for the control of growth and response to stress [168,169].…”

The Molecular Dialog between Flowering Plant Reproductive Partners Defined by SNP-Informed RNA-Sequencing

“…Analysis of GO cellular component annotations revealed 27.9% of transcripts encoded genes predicted to enter the endomembrane system (n = 74, P value = 2.72 3 10 215 ), which includes nine members of the rapid alkalinization factor gene family (27-fold; P value = 1.18 3 10 27 ; Supplemental Data Set 6), which have been found to participate in extracellular signaling (Haruta et al, 2014;Du et al, 2016;Stegmann et al, 2017). On the other hand, there were 476 pistilexpressed genes that were differentially regulated upon pollination: 216 were upregulated upon pollination, 259 decreased abundance upon pollination (Supplemental Data Set 7).…”

A Comprehensive Analysis of RALF Proteins in Green Plants Suggests There Are Two Distinct Functional Groups

“…Whether FER acts as a receptor for other RALFs is currently not clear, and no other RALF receptors have been identified to date. Very recently, the receptor-like cytoplasmic RPM1-induced protein kinase (RIPK) has been identified as an intracellular, interacting partner that is directly phosphorylated by FER and is crucial for the relaying of the RALF1-FER signal (Du et al, 2016). …”